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How Resistant Starch Will Help to Make You Healthier and Thinner


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resistant starch potato, raw potato starch
Potatoes and other foods are good sources of resistant starch. istock.com/peangdao

I asked Dr. Amy Nett, MD, to contribute this guest post. Amy initially completed her medical training in radiology at Stanford University Hospital, but wanted to work more directly with patients, helping them to prevent and reverse chronic disease and truly transform their health.  Combined with her passion for nutrition she decided to pursue a career in Functional Medicine.  You’ll be hearing more from Amy in the future!

Over the past several years there has been an exponential increase in the number of studies linking imbalances or disturbances of the gut microbiota to a wide range of diseases including obesity, inflammatory bowel diseases, depression and anxiety (1,2,3,4,5).  One of the best ways to establish and support a healthy gut microbiome is by providing the right “foods” for your gut bacteria.  These “foods” are called prebiotics.

Why you should add resistant starch to your diet. #healthydiet #resistantstarch #gutdisgestion

Prebiotics are indigestible carbohydrates, or at least indigestible to us, that reach the colon intact and selectively feed many strains of beneficial bacteria.  Prebiotics are generally classified into three different types: non-starch polysaccharides (such as inulin and fructooligosaccharide), soluble fiber (including psyllium husk and acacia fibers), and resistant starch (RS).  Each of these types of prebiotics feeds different species of gut bacteria, but among these, RS is emerging as uniquely beneficial.

The distinctive benefits of RS seem to be unequivocally recognized, even amongst advocates of a low carbohydrate diet

What Is Resistant Starch?

Resistant starch is a type of starch that is not digested in the stomach or small intestine, reaching the colon intact.  Thus, it “resists” digestion.  This explains why we do not see spikes in either blood glucose or insulin after eating RS, and why we do not obtain significant calories from RS.

There are four types of resistant starch:

RS Type 1: Starch is physically inaccessible, bound within the fibrous cell walls of plants.  This is found in grains, seeds, and legumes.

RS Type 2: Starch with a high amylose content, which is indigestible in the raw state.  This is found in potatoes, green (unripe) bananas, and plantains.  Cooking these foods causes changes in the starch making it digestible to us, and removing the resistant starch.

RS Type 3: Also called retrograde RS since this type of RS forms after Type 1 or Type 2 RS is cooked and then cooled.  These cooked and cooled foods can be reheated at low temperatures, less than 130 degrees and maintain the benefits of RS (6).  Heating at higher temperatures will again convert the starch into a form that is digestible to us rather than “feeding” our gut bacteria.  Examples include cooked and cooled parboiled rice, cooked and cooled potatoes, and cooked and cooled properly prepared (soaked or sprouted) legumes.

RS Type 4: This is a synthetic form of RS that I’m including for completeness, but would not recommend.  A common example is “hi-maize resistant starch.”

Once RS reaches the large intestine, bacteria attach to and digest, or ferment, the starch.  This is when we receive the benefits of RS.

How Resistant Starch Impacts Our Health

The normal human gut has hundreds of bacterial species, some good and some not so good.  The overall number and relative quantity of each type has a profound effect on our health and well being.  Resistant starch selectively stimulates the good bacteria in our intestines, helping to maintain a healthy balance of bacteria (7).

These good bacteria “feed” on RS and produce short chain fatty acids (through fermentation), the most significant of which are acetate, butyrate, and propionate.  Of these three short chain fatty acids (SCFA), butyrate is of particular importance due to its beneficial effects on the colon and overall health, and RS appears to increase butyrate production more when compared with other soluble fibers (8).

Butyrate is the preferred energy source of the cells lining the colon, and it also plays a number of roles in increasing metabolism, decreasing inflammation and improving stress resistance, as described in more detail below and previously in this great article by Stephan Guyenet.

Resistant Starch Helps to Lower Blood Glucose Levels and Improve Insulin Sensitivity

Insulin resistance and chronically elevated blood glucose are associated with a host of chronic diseases, including metabolic syndrome.  Several studies have shown that RS may improve insulin sensitivity, and decrease blood glucose levels in response to meals (10, 11, 12).  In one study, consumption of 15 and 30 grams per day of resistant starch showed improved insulin sensitivity in overweight and obese men, equivalent to the improvement that would be expected with weight loss equal to approximately 10% of body weight (13).

Further, RS has been shown to exert a “second meal effect.”  This means that not only does RS beneficially decrease the blood glucose response at the time it’s consumed, but, somewhat surprisingly, blood glucose and insulin levels also rise less than would otherwise be expected with the subsequent meal (14).

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Why the Popular Press Has Touted Resistant Starch as a “Weight Loss Wonder Food”

RS appears to have several beneficial effects that may contribute to weight loss, including decreased blood insulin spikes after meals (as discussed above), decreased appetite, and decreased fat storage in fat cells.  There may also be preservation of lean body mass, though further studies in humans are needed to confirm if there is a significant impact in overall body weight (15).

Further, several studies have shown alterations in the gut microbiome in association with obesity, which subsequently change towards that seen in lean individuals with weight loss (16, 17).  For example, one study demonstrated that the relative composition of the gut microbiota of two predominate beneficial bacteria, Bacteroidetes and Firmicutes, varied considerably in association with body composition. 

Specifically, obese individuals often have a higher proportion of Firmicutes to Bacteroidetes, which may be reversed with weight loss, gastric bypass surgery, or treatment with prebiotics (3).  However, not all studies confirm a significant or measurable change in the composition of the microbiome in obese compared to lean individuals, and further studies are needed (18, 19).

Butyrate Plays an Important Role in Gut Health and Decreasing Inflammation in the Gut and Other Tissues

As mentioned above, RS intake allows for increased production of butyrate by our gut microbes.  Butyrate acts as a powerful anti-inflammatory agent for the colonic cells, and functions to improve the integrity of our gut by decreasing intestinal permeability and therefore keeping toxins in the gut and out of the bloodstream. (20, 21).  

The SCFAs that aren’t utilized by the colonic cells enter the bloodstream, travel to the liver, and spread throughout the body where they exert additional anti-inflammatory effects.

Resistant starch is also associated with decreased risk of colorectal cancer, thought to occur through several different mechanisms including: protection from DNA damage, favorable changes in gene expression, and increased apoptosis (programmed cell death) of cancerous or pre-cancerous cells (22, 23).

Adding Resistant Starch to Your Diet

Some common food sources of RS include green (unripe) bananas, plantains, properly prepared cooked and cooled parboiled rice or legumes, and cooked and cooled potatoes.  See this link for a more complete list of RS quantities in food.

However, if you are on a low carbohydrate diet or don’t tolerate those foods well, you can add RS to your diet without adding digestible carbohydrates.

Bob’s Red Mill Unmodified Potato Starch (NOT potato flour) is one of the best sources of RS with approximately eight grams of RS in one tablespoon.  Potato starch is generally well tolerated even by those who react adversely to nightshades.

Plantain flour and green banana flour are also excellent sources of RS, and there may be benefit to including all three of these sources (specifically alternating your source of RS rather than relying on a single one).

These are relatively bland in flavor and can be added to cold or room temperature water, almond milk, or mixed into smoothies.  But to maintain the benefits of RS, these should not be heated above 130 degrees.

Tim Steele (Tatertot) has written about some of the research on RS supplementation, and in particular the potential further benefit of combining potato starch with psyllium husk fiber to even further increase butyrate production in the colon.

Take It Slow

If you choose to try supplementing with RS, start with small doses of about ¼ teaspoon once daily, and very gradually increase the amount as tolerated.  Some increased gas and bloating is expected as your gut flora changes and adapts, but you do not want to feel uncomfortable.  If you experience marked discomfort, then decrease the amount you’re taking for a few days until your symptoms resolve, and then try increasing again gradually.

Studies indicate that the benefits of resistant starch may be seen when consuming around 15 to 30 grams daily (equivalent to two to four tablespoons of potato starch).  This may be too much for some people to tolerate, particularly in the setting of gut dysbiosis, and going above this amount is not necessarily beneficial.

If you experience marked GI distress with even small amounts of RS, this may be an indication of SIBO (small intestinal bacterial overgrowth) or microbial dysbiosis, and you may need to consider working with a healthcare practitioner to establish a more balanced gut microbiome through the use of herbal antimicrobials and probiotics before adding RS or other prebiotics.

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Join the conversation

  1. Tim or anyone – I have been taking about 2 TBSP PS for a month or so now with good effect. However, if I consume Dandy coffee substitute (chicory, dandelion, etc. in it) the gas factor seems multiplicative. Does this suggest dysbiosis? Or just a bad food combo?? It feels like RS and inulin having a pillow fight in my gut. Not as sexy as it sounds. 🙂

    • Inulin is degraded by a completely different set of gut bugs, so it makes perfect sense what you describe. In nature, RS and inulin are never found together in the same plant for the most part, and really not even in the same geographical locations.

      If anyone wants to use inulin as their main prebiotic, they’ll find it’s even harder to get from normal food sources and needs to be supplemented at about the same dose as potato starch for good effect. Again, our paleo ancestors had no problem getting inulin in their foods, American paleo-Indians said to eat over 100g of inulin-like fiber/day.

      I have a jar of inulin powder and I add it to a smoothie once or twice a week just to mix things up. It always makes me more ‘vocal’ when I do it, too.

      • Thanks Tim! I will try not to consume them so close together… I cannot imagine what 100g of inulin would do. Warm up a teepee or cave at night, I suppose. 🙂

  2. I’ve tried RS in form of potato starch (not Bob’s red mill, I”m in Europe so it is inconvenient to order it from other contries atm). I got serious hives all over my body and it took me a few months untill they went away. I wonder since I didn’t have problems with my gut does this still might be a sign of SIBO? I’ve also written to Richard Nikolay about this, and he advised me to try hi-maize when I’m healed, but I’m hesitant to do that…

    • Hi Agne,

      I think you are absolutely right, and hives or other skin manifestation as a response to RS, could be due to SIBO or other gut dysbiosis. Gut bacterial imbalances may manifest with symptoms other than the more classic GI symptoms, such as skin rashes, hives, brain fog, or mood changes including dysthymia (depressed mood).

  3. Twice I’ve tried supplementing with RS steadily building up to the prescribed dosage and on both occasions it felt like my immune system fell apart. I am a healthy person (as far as I know) eating ancestrally for about 4yrs who would normally get a cold 1-2 times every 2 years but each time I’ve tried RS I have ended up getting colds every 2-3 weeks after RS for about 3 months. Anyone with any thoughts on what might be going on here would be much appreciated.

  4. Hallo Tim,

    Does RS starch also feed bad bacteria? In other words if I expect a overgrowth of pathogens does the RS feed them more than the good bacteria?



    • Yes, certainly it does feed pathogens. However, in a healthy gut environment, RS will mainly feed a few high-profile RS degraders that produce butyrate and also other end products that result in increased probiotic strains (eg. lacto, bifido). The entire gut ecosystem benefits by the lactic acid produces (create stable pH) and increased butyrate (feeds colonocytes and boosts immune system). Whatyou are after is a gut that takes care of itself and crowds out the pathogens and makes life miserable for them.

      If you are starting with a gutful of bad guys, all bets are off.

      Read all of Chris’ posts on RS and listen to his podcasts…he is taking this in the perfect direction. Use RS as a litmus for your gut health. Start slow and work your way up. Use probiotics to increase success of creating a healthy gut.

  5. I activate brown rice, then dehydrate and store in the freezer for cooking later. Will cooking, cooling and reheating (to 130 degrees C) the activated brown rice still provide resistant starch?

    • Activate? is that sprouting? Sprouting actually destroys RS, just basic plant physiology, but sprouted grains are great, so don’t let that stop you.

    • I have experienced more vivid and anxious dreams when using Bob’s Red Mill potato starch in my morning shake.
      Mark Sisson (Mark’s Daily Apple) has also mentioned this as have a few other bloggers/websites.
      Might be something more going on with gut bacteria when fed RS? Once again – clearly person dependent!

    • > … anyone experienced symptoms of anxiety and rage while taking RS?

      Your remark is the first I’ve seen on that since starting to follow this story early this year. Tim surely has more exposure to the possibly wide range of idiosyncratic reactions.

      > Then I came across these

      I’d like to see the full reports. The first is apparently pay-walled and the fulltext pdf of the second is 404. The abstract for the 2nd looks to have confounding factors, possibly fatal. All 3 diets were pretty high glycemic. The RS was cooked and cooled rice which is not very high in RS, contains wheat germ agglutinin and is often contaminated with high levels of arsenic these days.

      • Here you go


        I’ll try to dig up the other.

        Here’s the conclusion:

        In conclusion, increased fermentation with increased
        concentrations of lactic acid and VFAs in the hindgut of
        rats is associated with increased anxious and aggressive behaviour. The current rat model of acidosis appears to be a valid and reliable model to use for human research and has direct clinical implications. Researchers need to consider diet as an important methodological consideration, which can interact with a number of variables under investigation. The study of the mechanism of action leading to nutritional effects on anxiety and aggression warrants further empirical
        and clinical research.

        • Matt, my man! We got a lot to talk about!

          Two studies, one year apart, from the same guy on basically the same experiment. Done in Australia only a few years after the discovery of RS.

          A bit of background first: Australia has the world’s highest rate of colon cancer (CRC). Despite nearly 30 years of advice to “Eat Moar Fiber” their CRC rate went up. The Australian Health authorities (CSIRO) deemed that everyone should instead start eating more Resistant Starch. Not everyone liked this, namely because long-term studies had not been accomplished, and secondly because it was a government intervention from a government that is maybe not in the best position to tell people how they must eat.

          CSIRO’s effort to get people to eat ‘MOAR RS” involved teaming up with some Big-Ag types (Ingredion/Penford) who then developed some nifty new products, ie. BarleyMax and Hi-Maize. These high RS starches are to be added to cakes, cookies, bread, pasta, etc… so that the population will get their MOAR RS without having to actually think about it. CSIRO and these big-AG people spent millions/billions on advertising, making flashy fliers, and videos to show people how wonderful RS is. People don’t like that. I’d hate it. And, it kind of backfired on them as people rebelled against this new government plan.

          OK, to the studies:

          They are poorly designed, first off. They used cooked and cooled rice for the RS diet (FC diet) and wheat for the ‘stomach digested’ diet (SC diet).

          The SCFA amounts don’t follow their presumptions: Look at Table 3. Now that you know what SC and FC mean, try to form an assumption of SCFA concentrations that are amazingly different from each other or are way higher than the control. Butyrate at 21hrs, for example….highest in control diet. Total VFA (SCFA)…highest in wheat diet at 3 and 21 hours.

          pH not different among any diet. Nothing indicates the FC (high RS) diet is doing terrible things.

          Look at Table 4, the only thing that jumps at me is a dopamine level 400% higher on the SC (wheat) diet at 21 hours. This study should be used by Dr. Davis in his new Wheat Belly book.

          The rest of the tables looking at aggressive behaviors don’t really strike me as significant and in the conclusion the researchers all but admit their are too many confounding factors to make a good conclusion.

          The fact that this line of argument has disappeared and no more studies have come up with similar conclusions tells me that this was a dead-end, and just an attempt for these researchers to spark some new lines of study and thinking before making their entire country a nation of aggressive lab rats.

          Here is a much better study, in my opinion. It measures SCFA directly in ileostomy patients after being fed several different prebiotic fibers, including RS. Note Figure 1: It shows the amounts and percentages of SCFAs formed after fermentation in the large intestine. Each fiber type has its own unique signature. RS is not that much more amazing than inulin, but it does produce more butyrate than all the rest, which is somewhat amazing.

          Here is full text, I think this is a 90 day free trial, so download the pdf if you want to see it again!


          Now, to address the elephant in the room.

          I stopped trying to figure out what happens to people who add RS to their diet a long time ago. I will never say ‘you are making this up’ or ‘it’s all in your head’. Does anyone remember ‘Nancy’? Suffered terrible diarrhea after eating small amount of RS. She had her gut microbiome tested…25% of her entire gut flora was composed of Morganella Morganii, a major pathogen implicated in all sorts of illnesses.

          I still stand by my statement: If RS gives you problems, it’s not the RS–it’s you! Get your gut biome tested, do some interventions, don’t just accept poor health. If you are happy with your health and don’t do well on RS, don’t do it. That simple. We are all different. RS is not magic, just a fermentable fiber that certain beneficial gutbugs love to eat.

          Sorry for the inappropriately long comment!

            • Two ways of looking at this…if you just want to look ‘for fun’ without getting a doctor involved, there are American Gut ($99–takes 6 mo) and uBiome ($89–takes 2-3 mo).

              If you want an expert opinion, you’ll have to see a doctor. Many use a test called Metametrix GIFX or similar. This can cost considerably more but insurance often covers. Practitioners of functional and integrative medicine are more in tune with these tests than conventional medicine/family practice types.

              I don’t know any good doctors I could recommend…JUST KIDDING! http://chriskresser.com/clinic/services

          • Dear Tim Steele,

            Your passion is inspiring many people to become more aware of RS and to adopt it into their diet, but please take the time to properly research the staple crop varieties branded Hi-Maize and BarleyMAX. It’s important to make the appropriate distinctions between partnering to develop the varieties as opposed to partnering to gain access to the market (which has large barriers to entry due to the dominance of USA based big-AG).

            Since the 70s, the CSIRO has been investing in natural breeding programs to develop natural staple crop varieties that help solve public health issues. They are a science organisation, not a corporation (nor the national health organisation as you stated), so they have more recently partnered with large agricultural companies to commercialise new varieties developed by the CSIRO (independently of ‘big-AG). These partners have certainly not spent billions on advertising but are an important part of ensuring that the general public has access to products with these staple varieties included (given the barriers to market entry created by these USA based companies).

            The following article provides a detailed history of the products, which you claim in another comment still have ‘some mystery about them’.


            I’m really not sure what you mean by “it was a government intervention from a government that is maybe not in the best position to tell people how they must eat”, when referring to public health promotional campaigns to increase RS consumption. The Australian government has been the most progressive in promoting RS consumption (perhaps America would benefit from something similar given the issues with the Standard Americans Diet).

            Congratulations on the success of your book and blog on the benefits of Potato Starch and the ‘Potato Diet‘. Most people aren’t aware of the significant crop protection chemical residues in potatoes. The vast majority of growers spray the potato plant with herbicides just prior to harvest to reduce the mechanical strain on harvesters. It’s a process called Crop Dessication.


            We all talk about RS as the ‘feed’ for our microbiome but exposure to crop protection chemicals have an extemely harmful effect, particularly from Glyphosate (a ‘great’ chemical from the USA but thankfully the EU is moving first to phase out its use and let’s hope the world follows).

            I include some organic potato starch in my diet (note that Bob Mills does not claim to be organic) but personally try to maintain a few different sources of fibre and RS.

            There’s actually a great RS product from an Australian banana grower that developed a technique called NutraLock to maintain nutritional quality when processing green bananas. The company is called Natural Evolution and it has a green banana flour from the Lady Finger variety (again, this is non-GMO). This variety is higher in resistant starch than the Cavendish variety and is also high in 5-HTP.

    • Don’t take any probiotics with lacto bacteria strains. Focus on bidido strains that boost serotonin.

  6. Appreciate the article and have been waiting for you to write more on RS, but I was hoping you’d also give us your take on Mark’s response to this article:

    The Link Between Carbs, Gut Microbes, and Colon Cancer

    :in a recent post on his blog:

    Does Resistant Starch Cause Colon Cancer

    This is the part of his blog post that concerns me:

    “Chronic, low levels of butyrate exposure might be inadequate for protection and actually select for cancer cells that are resistant to the inhibitory effects of butyrate. Thus, if early adenomas are exposed to low butyrate levels, they can become butyrate-resistant (malignant) carcinomas if allowed to progress.”

    What is your considered opinion, and recommendation, especially for those of us who are older?

    • A peer reviewed to that study just came out: http://www.sciencedirect.com/science/article/pii/S1931312814002662

      Click on the pdf button and you can hear an interview, you may be able to find full text if you poke around some, too. Hopefully this article will get some good attention!

      From the full-text (hattip Gemma!)

      “Interestingly, the findings of Belcheva et al. suggest that butyrate functions as an oncometabolite, a provocative thought since numerous previous studies have identified butyrate as a tumor-suppressive metabolite (Bultman, 2014). In addition, R5 human microbiome sequencing projects have reported that CRC cases have decreased abundance of butyrate-producing bacteria compared to healthy controls. Furthermore, when butyrate is added to CRC cell lines, it decreases cell proliferation while increasing apoptosis and/or cell differentiation. In fact, butyrate-induced expression of p21 is responsible for the decreased proliferation of HCT116 cells (Archer et al., 1998). Yet, in the ApcMin/+;Msh2 А/А model, Belcheva et al. observed in creased butyrate levels in untreated mice were correlated with decreased expression of p21 (and increased cell proliferation and polyp number) compared to mice treated with antibiotics or provided a low-carbohydrate diet.

      How does one reconcile these seemingly disparate findings? Butyrate is a pleiotropic molecule that functions as an energy source, a histone deacetylase (HDAC) inhibitor, and an agonist of several G protein-coupled receptors. It may thus have different effects depending on the genetic background of the host. In this regard, ApcMin/+; Msh2 А/А tumor initiation does not necessarily involve dysregulated b-catenin expression, which is different from the more commonly studied ApcMin/+ and azoxymethane (AOM) models (Kongkanuntn et al., 1999). Furthermore, MSH2 deficiency results in a mutator phenotype that magnifies the somatic genetic background differences in the tumor (Reitmair et al., 1997).

      It is worth noting that this is not the first instance of a ‘‘butyrate paradox.’’ Butyrate has long been known to have differential effects on normal versus cancerous colonocytes, and only recently has this been addressed. Due to the Warburg effect, butyrate is metabolized by cancerous colonocytes to a lesser extent and therefore accumulates as an HDAC inhibitor (Donohoe et al., 2012). Similarly, butyrate may have heterogeneous effects on tumorigenesis depending on host genetic background, the presence of other bacterial metabolites such as an omega-3 fatty acid (docosahexaenoic acid), which synergizes with butyrate to induce colonocyte apoptosis (Kolar et al., 2007), and whether it is exerting a direct effect on the tumor (cell autonomous) versus non-cell-autonomous effects such as regulating mucosal immune cell activity as mentioned above.

      Therefore, although the current study contributes to our understanding of the interplay between diet, microbes, and CRC, the role of butyrate in cancer protection/promotion will still require further investigation. Altering microbial activities through dietary manipulation represents an exciting means to harness the microbiome and influence health and disease states. Whether dietary manipulation could be used effectively to preserve homeostatic functions afforded by microbiota while attenuating its potential pathological effects is still an open question, and more research would be necessary before this strategy becomes a reality.”

  7. So I’m wondering how much cooled rice (eg sushi) for 10g of RS. I tried to read the paper but info not easily accessible.

    • Rice is a pretty poor source of RS, sadly, and it is very type specific. The sticky rice used in sushi has the least of all rice, probably 1g per cup! Parboiled white rice can have 5g or more per cup. The colored rices (brown, black, red) seem to have more, but also other antioxidants and nutrients than plain white rice.

      If you eat a lot of rice, I’d recommend finding black rice…it’s absolutely delicious! If you are eating sushi just for the RS, it’s not so great, but sushi with rice, seaweed and raw fish is a ‘superfood’ combo in my opinion.

      • I spent a lot of time at various ethnic markets around my town trying to find some high-amylose, non-GMO, parboiled rice. No dice.

        I’m using Trader Joe’s organic basmati.

      • Lotus Foods line of rice (Lotus Foods dot com) is good for a diverse selection of rice — I love the Jade Pearl one, and also Volcano rice, literally grown on the side of a big volcano.

  8. > … you may need to consider working with a
    > healthcare practitioner to establish a more
    > balanced gut microbiome through the use of
    > herbal antimicrobials and probiotics before
    > adding RS or other prebiotics.

    This needed to be a bit more than a nearly offhand closing remark.

    RS is food for your gut flora. Thanks to modern diets full of gut antogonists (antibiotics, wheat, perhaps glyphosate uptake, and high glycemic foods generally), many people have deficient populations or adverse populations.

    I suspect that “take a quality probiotic when starting RS” needs to be routine advice. Probiotics are the bugs you’re trying to feed.

    What’s a quality PB? Well, if it’s on a room temperature store shelf, and is cheap, it’s probably not. Common retail PBs had insufficient CFUs of a poor spectrum of species at preparation, and may even be contaminated. But it hardly matters, because they’ve been mostly dead all day. You can tell by the usual laughable disclaimer “potency guaranteed at time of preparation”.

    It is possible to formulate a quality PB with a decent room temp shelf life, but your best bet may be found in the pharmacy fridge or store cooler shelves (or mail order where shipped in ice packs).

  9. Great article but seems a bit devoid of any real food ideas. Does anyone have recipes to share?

    • I think it makes sense, ancestrally speaking, to aim for 20-40g per day of RS. If you were eating raw tubers and sedge nuts as our early ancestors did, this would have been no problem.

      The best way to incorporate high RS foods into your diet is to precook potatoes, rice and beans. Store in fridge or freezer until ready to eat. You can reheat, RS will remain (long story).

      With these foods, you will get about 5-10g of RS per cup of food eaten. If you are good at math, you’ll quickly figure out this ends up being a lot of carb calories, too. So, as a stop gap, use raw potato starch in a smoothie or mixed with yogurt. In fact, as I’m writing this, I’m drinking a big glass of freshly juiced, somewhat dirty, carrots from my garden mixed with 3TBS of potato starch! Probiotics and prebiotics!

      Here’s a typical day:

      1 slightly green banana, green on the tips – 10g RS
      1 very small, raw potato, munched on while peeling potatoes to cook – 10g RS
      1/2 cup of rice and 1/2 cup of beans with dinner – 7gRS

      That’s 27g, roughly, from food. Add a TBS of raw starch later and you are well in the range.

      Other tricks – green plantains (sliced thin and dehydrated), nuts such as pistachios and cashews.

      As you get into the rabbit hole of RS, you find exact measurements are unknown and not listed very well anywhere. To increase RS in starchy foods, cook and cool. To get a gigantic dose with few calories/carbs, use raw potato starch or raw potato, green banana, green plantains.

      Nuts have RS…how much seems to vary, but they are a great snack and have several gut microbe boosting benefits.

      Hope this helps!

      • I’d like to increase my RS4 intake, but the problem is that I can’t stand cold or lukewarm food that is normally eaten hot. I like my potatoes and rice piping hot. Is the 130 degree figure here in Fahrenheit? And how far beyond 130 can I go without losing all the RS3?

          • 130 deg F will destroy RS2, raw starch granules. RS3, formed from cooked and cooled starches, remains intact during reheating up to 350-400 degrees after which the crystallized bonds melt.

            The RS3 can actually ‘grow’ if a dry-heat method of reheating is employed, such as stir-frying. RS3 is all about ‘staling’. As moisture is driven out, the RS3 bonds become stronger and more RS is formed.

            To reheat rice and potatoes, my favorite way is to quickly stir-fry in coconut oil or animal fat. Probably worst methods are by steaming or microwaving.

            BUT, no matter how you reheat, the differences aren’t all that huge. For instance, potatoes stir-fried may end up with an RS content of 10% and if boiled and mashed, 7-8%.

            • Tim,

              Thanks very much for the follow up answer to the 130 degrees issue.

              Could you edit the article with this info?

              The way it currently reads it sounds like any (re)heat over 130 destroys the RS3.


              • I just looked at the cite used by Dr. Nett for that discussion. The study linked is a really good one and has a great discussion on retrograded starch.

                It says at one point:

                “It is worth emphasizing that in order to undergo rehydration the products of amylose retrogradation must be heated at temperatures over 120°C, whereas those of amylopectin retrogradation require
                temperatures slightly over 60°C”

                I never realized there was a difference here. Some starch will lose retrograded RS when heated about 248 deg F and some will lose it above 140 deg F. According to this article.

                I guess with high amylose products, ie. Hi-Maize, the upper limit is valid, but for foods that have a large proportion of amylopectin the lower should be observed…interesting!

                Later in the paper it states:

                “Amylopectin is also capable of retrogradation, however
                in its case retrogradation is a long-term process requiring
                several to a dozen or so days of starch paste storage at an
                appropriate temperature. The process is more efficient
                when the starch paste is cooled and heated several times.
                Retrogradation of amylopectin results in the formation of
                crystalline structures built of chains with a polymerization
                degree ranging from 6 to over 50. Temperature of their dis-
                solution ranges from 30° to 80°C, depending on the botani-
                cal origin of starch and conditions of the retrogradation

                Did you follow that?


                This paper shows that potatoes, rice, corn and wheat all have about 20% amylose:80% amylopectin.

                As we now know that amylopectin is harder to retrograde and quicker to dissolve, I think we can assume that most RS3 in the foods we eat is formed from the amylose portion.

                So, I would say that the article is correct. Don’t heat RS3 over 130 degrees F if you want to keep all of it’s resistance. High amylose starch products can be safely heated up to 248 degrees F, however.


                I learn new things every day!

                I just looked at a study I had (http://www.academia.edu/4671300/Resistant_Starch-_A_Review) it states:

                “….the main RS, consisted of retrograded amylose … with a melting temperature of 150 °C…”

                This is probably the source of the error. I will be going with the lower temperature from now on to be on the safe side. Still, reheating by quickly frying in hot oil has been shown to preserve the most RS3. Probably because the bulk of it is not heated above 130, or because amylose is actually the prevalent starch in RS3 products..

                Maybe the advice should be ‘gently or quickly reheated being careful not to exceed 130 degrees.’

                But if you mess this step up, you are probably still OK as most of the RS3 was from amylose unless you took active steps to heat and cool the starchy food several times.

                Confused? So is the whole world…this is complicated stuff, man!

                • Tim,

                  Thank you for the extremely detailed reply.

                  I think I followed everything you laid out, but I also think this topic deserves further exploration.

                  So Fried Rice is still good for RS3 preservation (at relatively lower heats)

                  What about beans? Lentils? If I make lentils, or stew w/ beans and reheat in a pan, how in the world am I supposed to know if I am heating them above 130 or not? Use a food thermometer everytime I warm up leftovers?

                  Would really love to see a detailed and expanded blog post on this on your site or Richard’s. (and maybe a section in the book 🙂

                  I’m just worried myself and a lot of people are losing a lot of the RS and potential benefits they think they are getting – this information seems to change a lot of recommendations.

                  Thanks again!

                • Hey, yeah, it’s not really very intuitive or user friendly, I know. That’s mostly why I jump into threads like this.

                  The actual, exact RS content of real food is extremely difficult to measure and that’s why it won’t be on a food label unless it’s RS placed there on purpose.

                  The reason I like potato starch is because it is a known quantity and easy to dose accurately and repeatably.

                  There are some absolutes that make getting and using RS easier:

                  – Green bananas and raw potatoes are a great source of RS2.

                  – Potato starch and banana flour are great sources of RS2.

                  – Cooked and cooled beans, rice, potatoes, yams, and plantains are great sources of RS3. OK to reheat. Exact amount is impossible to determine.

                  – The average intake of RS in the US and most other countries is well under 10g per day.

                  – 20-40g/day is an amount of RS shown to create a better microflora in numerous studies.

                  – RS2 alone is not advised for one’s sole fiber source…better to also include RS3 and as many other fibers as you can get from real foods. Supplement sparingly if at all.

                  – Using potato starch to bridge a gap in a lowish fiber diet is perfectly fine if you can tolerate it.

                  – If you can’t tolerate PS, use banana flour or inulin.

                  – Someday someone will sell starches labelled with their RS content. Until then, do the best you can. It’s nothing to lose sleep over.

                  – And finally, we learn new things about RS and the biome every single day. Until we know everything, we just do the best we can.

          • One of my favorites. Use cold rice, milk (real or coconut), and a couple spoonfuls of potato starch…that’s a high RS treat! Sweeten as desired.

              • If you use the potato starch and the rice is leftover rice, there probably won’t be much glycemic load–test to confirm, though.

      • Tim, how long should you cool the cooked rice or potatoes before eating in order to obtain the RS benefits?

        • Great question! Here’s the scoop:

          The retrograding of readily digestible (cooked) starch begins at about 50 deg F and proceeds down to about 10 deg F. The formation of retrograded RS (RS3) is also time dependent.

          About 75% of the RS3 will be formed by chilling to 40 degrees for 8 hours, ie. ‘overnight in the fridge’. Further lowering of temperature and longer time in cold storage will eke out another 25%. The biggest bang for the buck is ‘overnight in the fridge.’

          I like to make big batches of rice, beans, and potatoes. I store potatoes in the fridge for up to a week or so as they don’t freeze well. Rice and beans freeze well, so I store these in the freezer.

          Preparing in this method is a huge time saver and makes fixing bean/rice/spud dishes much quicker than preparing from fresh each night. It’s also more ‘ancestral’ if you think about it, cooked foods weren’t prepared ‘on-demand’ until the last hundred years or so. Leftovers are good food!

          • Hi tim.
            Can i just say i am in awe of your mind and the knowledge you have. I am so impressed with the information you have and how you are helping all of these people by answering their questions.
            Amazing job.

      • I have been making a GF bread in which I have substituted part of the GF flour for tapioca starch, banana flour and ground flax seed, does this mean that I have been getting RS without even knowing it? I allow myself I slice of this bread every day but I usually toast it, would it be better for RS to have it untoasted? I have autoimmune thyroiditis, gluten intolerance and a candida problem and keep to a very low carb diet and take probiotics.

    • Per my potato salad comment above, here is the best-ever potato salad recipe, from my Grandma with my own twist:

      Grandma Strickholm’s Potato Salad

      Take a bunch of potatoes. She used brown-skinned, I tend to mix it up.

      Wash them. DO NOT peel them. Cut them in quarters or sixths.

      Dump into a huge pot of water, salt (1 T.?), and boil away. When the potato pieces (which will seem pretty large still) are just barely cooked in the center.

      To check for doneness, take out a representative piece from the pot, and pierce it with a knife and fork. It should feel firm but not hard. The outside peels will be coming off a bit.

      Drain in a colander thoroughly, shaking a few times. It’s important to get out all the water, and to do it fast. Don’t leave the colander sitting in the sink for a half-hour, or this recipe won’t work.

      Put the potatoes back in the pot, or use a bowl (Grandma always used the big heavy pot she boiled the potatoes in, which helped give the potatoes the slowest-possible cool-down).

      Pour 1/4 – 1/2 cup of fresh-squeezed lemon juice. (Oh yeah, prep that before you boil the potatoes!) Just do it — trust! Stir carefully a few times. Set aside to cool. I just throw a dish towel over the whole shabang.

      The idea is, the potatoes continue to cook from their own heat for a little while, and absorb the lemon juice and aroma.

      Once the potatoes are cool enough to the touch, take each piece and cut it into smaller chunks. Grandma still left it really chunky. There may be some lemon juice (or a lot) left in the pot. That’s as it should be. You can either drain it off and add back in to your taste, or just leave it in the pot for the potato salad — what Grandma does and I do.

      Stir in mayonnaise (paleo or Grandma’s fave, Hellman’s), until all potatoes are covered. Then stir in salt, pepper, and minced chives.

      My additions: I also stir in minced red onion or Maui sweet onion, some flat-leaf chopped parsley, and roughly chopped hard-boiled eggs, at the very, very end so they mostly remain intact chopped pieces.

      It may look soupy. Don’t worry. Turn the whole thing from the pot into a big bowl, cover well, and refrigerate overnight. You may have to stir once or twice the next day, but it should be just about perfect. Enjoy!

  10. A great article and discussion.
    To make potatoes more palatable does potato salad ( potatoes cooked then cooled) still offer RS benefits?

      • OMG I seriously LOVE potato salad! My grandma made the best potato salad, and I’ve subsequently added a few twists of my own (hard-boiled eggs, fresh flat-leaf parsley). I’ve missed it greatly since entering the paleo world. I think I can pull it off with the paleo mayonnaise in the WellFed2 cookbook.

        • Yes, good news, potato salad appears to be super-Paleo in the original sense of Paleo that Dr. Boyd Eaton hypothesized–foods that humans are biologically well adapted to. YMMV

  11. I keep trying to take RS in potato starch form but the gas and bloating is bad and since I have FODMAPS intolerance and have been unable to heal my gut I wonder if I should keep persisting.

    • Hi Kat,

      Your continued gas and bloating, along with FODMAPs intolerance suggest an underlying dysbiosis that may respond better to a period without RS, or other prebiotics. I would not suggest you persist taking the RS, as RS may be feeding the pathogenic bacteria just as much, or more, than the beneficial bacteria. If possible, you may want to consider working with a health practitioner for further GI testing and possible treatment with herbal antimicrobials.

      • Hello,

        You respond to Kat by saying “RS may be feeding the pathogenic bacteria just as much, or more, than the beneficial bacteria” yet your article says “Resistant starch selectively stimulates the good bacteria in our intestines, helping to maintain a healthy balance of bacteria (7)”.

        There is always nuance but how do you reconcile this?

        I tried to follow reference 7 but it is pay-walled. Could you please provide the full-text? Alternatively, would you mind further detailing their findings? Thanks.

        The variation in response to RS is not surprising given a little thought:
        – More people than not do not eat normal amounts of fibrous vegetables and so introducing RS is expected to be more beneficial than not, most of the time.
        – OTOH, a lot of people have dysbiotic guts and unsurprisingly, a substantial number of people cannot tolerate RS or other fibres (or don’t see the promised improvements).

        With this in mind & considering the wide, diverse range of microbes fermenting sugars into butyrate (& other organic acids), are we currently in the position to explain RS’s supposed ‘feed selectivity’?

        I think not.

        Regardless, I have 2 bags of Bob’s RedMill Unmodified PS sitting in my fridge waiting to make its entrance in my N=1.

        • Hi,

          Yes, in general RS does primarily feed and encourage a few specific strains of beneficial bacteria. However, this must be taken in the context of a healthy gut environment. If a patient has severe dysbiosis, there may be too few of the beneficial bacteria to ferment the RS, and it may then be fermented by more pathogenic strains of bacteria. If RS is not well tolerated, it suggests underlying dysbiosis that should be treated prior to adding RS to the diet.

          Reference 7 is a 15 page review article, and I included that reference because it points to a few different studies looking at how RS changes the gut microbiome, though acknowledges that further advances in analytical techniques with subsequent further studies will contribute to more fully characterizing the potential changes of the microbiome. That said, several studies do suggest that RS particularly supports certain beneficial strains such as Bifidobacter and Lactobacilli. Here’s an additional reference that you should be able to access at no cost with some more specific information on RS and specific bacterial species:

          • FWIW, I have a dysbiotic gut and tolerated RS from multiple sources rather well, with just a bit of early flatulence at higher intakes. Responses seem to vary greatly between individuals, perhaps due to different species of bacteria populating different guts. There are many different RS sources to choose from, and also other prebiotics, such as the inulin, larch AG, and beta glucan that Tim Steele mentioned, as well as others.

    • I had a great deal of gas and bloating when I first tried potato starch, which eventually went away once I started mixing Soil Based Organisms (Prescript Assist) into the PS. There was no improvement until adding the SBOs, though.

      As several people have said, you should also focus as RS3 from cooked and cooled rice, potatoes and beans (but maybe not if you have FODMAP issues, and must be properly soaked and cooked). It is important to get RS3.

      • I forgot to say that you need to start slow when you mix Prescript Assist into your PS. Maybe just half or less of a capsule to be on the safe side. The first time I did it I had extremely bad gas.

  12. I appreciate your mentioning that people who may react to nightshades seem to tolerate resistant starch well. Can I assume correctly then that people with autoimmune diseases can safely consume this?

    Like Anne above, I’m interested to know your thoughts about supplementing with resistant starch if you are following the Specific Carbohydrate Diet or GAPS since its premise is to eliminate starches. Do you think adding the resistant starch would be negating the purpose of SCD or GAPS?

    • Hi Amber,

      People with autoimmune diseases can safely consume resistant starch. And some of these people will be able to tolerate unmodified potato starch. However, some people who react adversely to nightshades do not respond well to potato starch, and need to use alternate sources of RS, which may include plantain flour or green banana flour.

      Regarding resistant starch for people following an SCD or GAPS diet, it really depends on why you are choosing to follow that diet, and which foods you tolerate well. Specifically, though many people use the GAPS diet to heal various neurologic, digestive or auto-immune conditions, it is often not required as a life long dietary prescription, and people may eventually be able to reintroduce foods containing RS. Similarly, some people who do well on SCD, are often able to incorporate some “safe starches” (such as plantains, sweet potatoes, parsnips, etc.) after an initial period of healing.

      If you are just starting out with an SCD or GAPS diet to begin healing, then I would not recommend adding RS to your diet, but rather focus on healing your gut and improving the microbiome before adding RS.

      • Amy,

        Thanks for taking the time to respond and for your thoughtful response. I’m glad to see you’ve teamed up with Chris and am looking forward to reading more articles from you.

  13. Would greatly appreciate Dr. Nett or anyone who has an understanding of Celiac to comment on my question.

    How would one introduce such starch that clearly has been show to be pernicious to the small intestine of those afflicted? It is even more of a problem in older Celiac sufferers.

    Dr. Sydney Haas and SCD diet have done significant research to the serious problem when ingesting starch.

    • Hi Anne,

      I think the best approach to introducing resistant starch, particularly in the setting of Celiac disease or other cause of GI distress, is to start very slowly with small amounts of either food sources or supplements. If after a few days of taking a small amount (maybe ⅛ teaspoon) of RS, you have uncomfortable symptoms, that may be a sign of more acute dysbiosis that needs to be addressed before adding RS to your diet.

      Unfortunately, there is no one answer for everyone, and the amount of RS a person can tolerate may change over time. For example, during times of increased life stress, underlying gut symptoms or dysbiosis may be exacerbated, and the person may need to to decrease the amount of RS in the diet.

      Some of the “safe starches” in the SCD contain RS, so it is a matter of experimenting and finding what works best for you.

  14. Thanks for the very informative article. I was hoping to see the resistant starch content for raw potatoes, but unfortunately this data was unavailable in the research article that was linked, which has also been the case in previous lists that I have viewed (such as the one at Freetheanimal). Has anyone found any RS content for raw potatoes or is there any other way to measure the content per 100 g as in the article?

    I have just considered raw potatoes easier than the cook and cool method and also better than potato starch. Potatoes are quite nutrient and significantly cheaper than potato starch, if you take the 4 tablespoons required to reach 40 g RS per day.

    • I don’t mean to take over, but I just love this subject!

      Here’s a breakdown on raw potatoes:

      Potatoes have roughly 16-20% starch content, the starch is about 80% RS. So 100g of raw potato would have 16-20g of starch or roughly 15g of RS.

      In other words, a 100g raw potato is the equivalent of 2TBS of potato starch.

      When I first started talking about RS, I used to advise eating raw potatoes, but people were aghast at the idea. I have done this myself for years with no problems, and Dr. Davis of Wheat Belly is also advising it now. If eating raw, be sure to peel and remove any green spots/eyes. If you have a nightshade intolerance, you’ll already know not do do this.

      There’s a little talked about chemical found in raw potatoes known as kynurenic acid (KYNA):

      “… KYNA possesses anti-ulcerative properties. Furthermore, it is known that KYNA shows anti-inflammatory properties and antagonizes hypermotility of the intestine in an experimentally induced colon obstruction. KYNA, as an antagonist of NMDA receptors, decreases motility and inflammatory activation in the early phase of acute experimental colitis in rats. Moreover, it has been stated that KYNA decreases proliferation of colon derived cancer cells in vitro, and that its content in the intestinal mucus is increased in patients with diagnosed colon lesions such as adenoma or adenocarcinoma. Finally, it has been shown recently that KYNA possesses antioxidative properties.

      Potatoes contain one of the highest concentrations of KYNA among food. It is worth mentioning that only various kinds of honey contain more KYNA than potatoes.”

      That was from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3304068/ (hattip Marta)

      • Tim,

        I’ve found your research on RS to be extremely helpful, so thank you very much for adding your comments on this topic!

        • You are quite welcome, hope you didn’t mind me jumping in on the technical RS questions.

          RS is such an amazing topic, seems too simple at first glance, but the studies over the last 30 years and more that come out near daily show it is anything but simple.

          Let me know if you ever have any questions you need help with.

          You are going to love Chris and team…lots of people being helped.

          • Hello Tim,

            Very interesting information on resistant starch. Thank you for taking the time to address these questions. I’m a sauerkraut maker and I wonder how the RS of raw potatoes would change if grated and fermented with cabbage and beets?

            • I think it might be destroyed. The potato starch granules would become compromised by the pre-digestion from lactic acid bacteria.

              I’d think this would put the digestion resistant qualities in jeopardy.

              I make sauerkraut, too. Just cabbage, though. Also beet kvass…an aquired taste but a great source of free summertime probiotics.

              • Will the lactic acid bacteria in yogurt not destroy the potato starch powder we mix into it then?

          • so how did our ancestors take in resistant starch? i don’t think they ate bobs red mill potato starch … (:(:

            • FINALLY! Why does it always take so long for this question to get asked? Thank you, Elizabeth.

              Before humans learned to cook, we ate raw tubers (such as yams and sedges), seeds, nuts, and other RS2 containing food sources in great quantity. Then, when we learned to cook, we still ate these same foods, only now we heated some of them up. Cooking ‘back in the day’ wasn’t to short order, it would have been done by heaping tubers on a bed of coals and letting them cook, eaten for days after the fire went out. This created a new RS…RS3. Cooking of native African yams is still done this way by the Hadza as they have for millions of years. These aren’t sweet potatoes with little marshmallows melted on top, these are big, ugly yams that sometimes get over 50 pounds in weight.

              When we left Africa, we sought out starches wherever we went. Cattails throughout Europe, sago palm starch throughout Asia. Where bananas and plantains grew, the greener ones were prized more than the ripe ones. Ripe, yellow bananas attract bugs and go bad fast. Green ones keep longer and don’t attract ants and gnats. When you feed a village with bananas or cassava, you can gather them in mass quantity, peel, mash and pound into a dish known as fufu. Still done today in many parts of Africa and Asia by the name fufu and others–and full of RS.

              As man travelled to America, he encountered corn, beans, squash, cactus, and potatoes. All of these are full of rich fibers and/or RS. Early potato consumption was of the starch, not the potato because wild potatoes are mostly poisonous, the extracted starch not so. Lots of dishes in Peru still revolve around potato starch.

              Also, in Africa at the dawn of Man, was found the tuber of a sedge called Cyperus Esculentus, aka tiger nuts, aka chufa. These were eaten by early man and later cultivated by the Egyptians and Spanish…as they still are today. A wonderful drink called Horchata de Chufa is a raw starch drink consumed widely for eons. Has anyone ever seen that strange drink in a cold mixing tub in a Mexican/Spanish restaurant? Horchata needs to be kept cold and constantly stirred to prevent the starch from settling. Unfortunately, Horchata is made mostly from cheaper rice starch today, but in Spain, Horchata de Chufa still reigns.

              Throughout the history of mankind, we enjoyed resistant starch. Whether by accident, luck or design, it’s undeniable that RS is a big part of our past.

              After we marched out of Africa, the first areas we settled were filled with palms. Palmae is one of the oldest plant families on earth and many early societies developed entire lifestyles in synergy with the various palm species:

              •Date palm (Phoenix dactylifers) – Arabs of the sub-Saharan
              •Palmyra palm (Borassus flabellifer) – Inhabitants of South India
              •Lontar palm (Borassus sundaicus) – Roto islanders of Indonesia
              •Coconut palm (Cocos nucifera) – Indo-Pacific Islanders
              •Oil palm (Elaeis quineens) – West Africans
              •Sago palm (Metroxylon sagu Rottboll) – Malaysians
              •Moriche palm (Mauritia flexuosa) – American Paleo-Indians

              What all of these palms had in common were amazing sources of fiber, particularly resistant starch. For instance, the Sago palm was the main source of subsistence throughout southern Asia until rice was introduced in 2500 BC. The sago palm is an amazing RS factory. The first part of its life it looks like a short, trunkless palm tree, but when it is about 10 years old, it will send up a trunk 20-30 feet tall after which it flowers and dies. The year before it flowers, the large trunk is filled with up to 2000 pounds of easily extracted starch. The starch is unique in that it was easily isolated and dried, and when cooked and cooled, retrogrades into one of the most stable RS3 sources on the planet. Products made from sago starch can be stored for exceptionally long periods and helped the seafaring Malaysians travel far and wide throughout the Malay Archipelago. To this day, 25-40,000 tons of sago products are exported annually from Malaysia to the rest of the world.

              One of the best sources of RS2 comes from the mountainsides of Asia.

              Dioscorea opposita, also known as Nagaimo, Japanese Mountain yam, Chinese yam, and Korean yam. It is often used in the Japanese noodle dish tororo udon/soba and as a binding agent in the batter of okonomiyaki. The grated nagaimo is known as tororo (in Japanese). In tororo udon/soba, the tororo is mixed with other ingredients that typically include tsuyu broth (dashi), wasabi, and green onions. Also eaten in China, Japan, Vietnam, Korea and the Philippines.

              Raw Chinese yam (Dioscorea opposita) is an excellent source of RS.

              “We examined the effects of raw Chinese yam (Dioscorea opposita), containing resistant starch (RS), on lipid metabolism and cecal fermentation in rats. Raw yam (RY) and boiled yam (BY) contained 33.9% and 6.9% RS, respectively…These results suggest raw yam is effective as a source of RS and facilitates production of short chain fatty acid (SCFA), especially butyrate”

              Our past is filled with ample consumption of RS2, raw starch granules:

              There were also societies that utilized isolated, raw starches (RS2) in a variety of clever, tasty, and interesting ways, but never as a main source of calories and nourishment.

              •Horchata de Chufa, a tiger nut starch drink that is still enjoyed by many around the world even today;
              •Fufu, a starchy dough made from cassava root eaten in Africa;
              •Chicha, similar to Horchata de Chufa but made with corn
              •Chuno, a dehydrated potato staple of the Andes
              •Tororo, made of the Asian yam Dioscorea opposita, often eaten with Natto
              •Nuts and Seeds, probably every single culture in the history of mankind has enjoyed munching on raw nuts and seeds. Sunflower seeds, pumpkin seeds, chia, flax, and all manner of tree and ground nuts are universally enjoyed by people around the world and contribute to a healthy gut

              Additionally, much evidence of RS3 consumption abounds:

              •Yam cakes
              •Dried, cooked tubers (ie. potato chips)

              It may be the “leftovers” that have given us our biggest supply of RS3 over the years. People living in so-called “Blue Zones” known for tremendous longevity are known to subsist on meager rations of leftover pasta and legumes.

              Not that I’ve given it much thought…

                • Bah! Just a bunch of wikipedia regurg…

                  This knowledge has been around for 30+ years. I’m just digging it up.

                  Read this statement by the World Health Organization:

                  “One of the major developments in our understanding of the importance of carbohydrates for health in the past twenty years has been the discovery of resistant starch.”

                  — Joint Food and Agricultural Organization of the United Nations/World Health Organization, 1997

              • Thanks Tatertot! I’ve read your info back when at Mark’s Daily Apple and I am so glad you have added more clarification (and history) because I’ve been wondering about it every since then.

                Do cooled sweet potatoes have high amounts of rs? If so, how many grams do I need to get the 15-30 g range? I tried the potato starch for a while and it aggravated my SIBO so I stopped. But I do tolerate yams and sweet potatoes well so I wonder if I can go that route instead.

                • Sweet potatoes are a funny food, RS wise. They don’t have much when eaten raw, but the starch seems to retrograde at a much higher rate than other starches, so cooked and cooled (optionally reheated) sweet potatoes are a very good choice for your diet.

                  Sweet potato starch noodles are shown to have very high RS when cooked, the highest of all starch-based noodles.

                • That’s good to hear re sweet potato noodles- I buy a variety that are made from buckwheat and sweet potato. Looking at the list of foods on Freetheanimal (did you come up with that Tim?), buckwheat seems to be a good source of RS too.

              • This is fantastic information. I have been a long time taker of PPIs and am very keen to improve my gut health, having some success with raw apple cider before each meal, eating activated seeds and nuts and about to incorporate some of the other RS foods. Fingers crossed!

                • Tim,
                  Are you familiar with the SCD and/or GAPS diets? These diets seem to restrict RS (and other starches) in order to starve out the pathogenic gut bacteria. I have some patients doing very well with the diet, but wonder if/when to introduce RS. I have always wondered about the fact that these diets starve out the pathogens and most likely also the good bacteria – or at least do not feed them well. I wonder how a person with IBD and doing well on a GAPS type diet would do with some RS. Do you have any idea? Or anyone else?

                • Jill – Perfect timing! I may have a good answer.

                  Yes, I’m familiar, and not a fan, BUT, some people may need these type of diets until the day comes when we can tailor or microbiota.

                  What I hate about these diets is that people who don’t require them use them. These diets need to be reserved for people that truly cannot digest/ferment certain fibers.

                  For all other people, RS and the Microbe-assessable carbs need to be eaten regularly.

                  I think the only way to transition off GAPS or SCD is by trial and error, or a gut biome test.

                  I will have a blog post up tomorrow showing my uBiome test results and how to look for some key microbes.

                  Without a test, it’s all guesswork.

                  If your patients are doing well on these diets, but can’t tolerate phasing fibers back in, they most likely are missing some key microbes that will only be replaced by fecal transplant. Probiotics don’t contain the right species.

                  Hope that helps!

              • Tim, excellent! I love reading things like this. In reading older stories especially the Beatrix Potter stories I noticed a canister in the kitchen in one of her illustrations that was marked “sago”. Interesting.

          • Hi Tim, I’ve followed your work for almost a year now and have been experimenting successfully with PS. It seems like the direction this is heading is in more diversified forms of RS, not just BRM potato starch, and RS3 is piquing my interest. My question is, do you have “optimal” preparation methods for cooked and cooled potatoes? So far I’ve skinned some potatoes, roasted them in medium heat for 1 – 2 hours, then frozen them for 24 hours or more and then added them to my morning smoothie. Can you say what you know about whether this is a good RS3 preparation method? Any feedback or direction would be appreciated.


            • Your method is probably the best for making RS3.

              Just think ‘leftovers’.

              No sense sweating it too much, just make leftover starches a part of your diet plan and you are good to go. I pre-make beans, potatoes, rice and store in fridge or freezer. This is probably the easiest way to do it without getting all orthorexic about it. Eventually the numbers will balance out in your (gut bugs) favor.

              Add to this a slice or two of raw potato now and then, a green banana, and snacking on nuts and seeds, and you have it down perfectly.

              Also, think about expanding your palate to inulin…onions, garlic, leeks, dandelion roots, Jerusalem artichokes as well. Inulin has about exact same effect as RS on gut health, but almost even harder to get from your diet without targeting certain foods.

              Eat plenty of RS and Inulin rich foods, and you are guaranteed to be getting all the other minor fibers you require (pectins, gums, mucilages, etc..).

              Hope that helped! I have a good fiber tab on my blog if you click my name.

              • A terrific source of Inulin, and perhaps even some RS (but I’m not really sure) is Jicama. I recently started eating it and it’s pretty awesome. Safe to eat raw and tastes like an Apple but a lot more fiber.


                Pretty easy to find in many supermarkets. I definitely think it’s one of those easy fibrous vegetables that most people overlook. It has a very mild taste, so even picky kids would eat it with a little honey.

              • Thanks Tim, that’s awesome.

                So it sounds like that’s about as “exact” as I need to be. One more clarification though, I read in one of your other comments a back and forth about reheating temperatures (130 vs 240 or something) and I was wondering if these heat restrictions only apply to the REheating or to the original roasting as well – before the cooling?

                Thanks for suggestions about Inulin! I’ve experimented with adding some NOW inulin powder in with the potato starch, about 1 teaspoon, but haven’t noticed anything particular. As for food sources, do you find it ridiculous I’ve been avoiding onions and garlic because of Dave Asprey’s claim that they reduced his cognitive performance?

                Is Inulin affected by heating the same way as RS? Just wondering if the onions, garlic, leeks and dandelion root should be raw or cooked….

                Thanks again.

                • I like to think a mixture of raw and cooked onions/garlic/leeks etc.. is the best. Again, don’t sweat it–just include them regularly.

                  I have heard that inulin breaks down at high temp, but then other changes take place that can be beneficial. Just don’t burn/char them.

                  Also, I’ve been told that if you salt crushed, raw garlic it elicits even greater immune response and antiinflammatory activity.

                  As far as initial heating. No real concerns. RS2 melts into regular starch at about 140 degrees. Those temps we talked about are more critical for re-heating. But again, don’t waste too much time over-thinking it…eat leftovers sometimes cold, sometimes cooked in a variety of ways and it will all balance out.

                  Duck – Jicama I can find! I need to try it. It has always mystified me. So just raw? That I can do!

                • Raw jicama with some chilli powder, lime juice and salt is delicious. Crisp, crunchy slightly sweet and easy, peasy.

                • Ben R. wrote: “do you find it ridiculous I’ve been avoiding onions and garlic because of Dave Asprey’s claim that they reduced his cognitive performance?”

                  Yup. 😉 Almost as ridiculous as an Irish-American like me mostly avoiding potatoes for years because of Ray Audette and Loren Cordain’s negative claims about them. I thank my lucky stars that I came across Tatertot Tim and a dude with the handle Muhammad Sunshine reporting marvelous benefits from resistant starch. I was quite skeptical at first.

                  Tim, Get going on the jicama, man. I don’t want to have to keep nagging you about that. 😉 Just be sure to get a small, fresh one that doesn’t have dimples that look like air bubbles on it. The bubbles mean it’s overripe, and they get quite bitter when overripe.

                • Hey Tim, one more question. What part of the dandelion is the good stuff? You mentioned Dandelion root above but I see you talk about Dandelion greens somewhere else. I was able to find some greens in the local grocery store and cut these up, but they are incredibly bitter. Without the stems seems better, but don’t want to be doing it at all if it’s only the roots that are good!

                  Oh, on your website it specifically says the greens…. So does that include the stems!?

                  Thanks again man,

                • Ben – All of the dandelion is good. Leaves and roots both full of inulin.

                  But eating it is a different story!

                  I’ve never bought any at the store. In the spring, I find dandelions that have just popped up. All leaves, no flowers or stems. Sometimes you find tightly packed flower buds in the center, but with no stems yet.

                  In this stage, dig them up, root and all. You will find not a hint of bitterness anywhere, the root is actually very sweet.

                  When the flowers start appearing, the bitterness starts. You can still eat the leaves, but the root starts to get bitter, the stems with their milky white sap is extremely bitter. People have been making wine with the flowers forever, and they can also be gathered and eaten, unopened if possible…lots of magic in flower buds: Google Gemmotherapy (that’s your homework) (hattip, Gemma, natch).

                  OK. Raw leaves and roots in early, early spring.

                  Later as they become bitter, or the leaves you find at Safeway. Try this:

                  Wilted Dandelion Salad

                  Fry 2-3 strips of bacon, the fatty stuff. Remove bacon, leave fat in pan. Turn off heat. Toss the dandelion leaves straight into the hot fat, stir fry a bit until wilted. Add a splash of vinegar and maybe a dash of sugar (I use coconut sugar). Toss lightly and serve hot covered in….BACON!

              • Hey Tim,

                So I finally found some Jerusalem Artichoke in the store today. Any tips on preparation? You like this one better raw or cooked? Now before you say “don’t sweat it” I’m just looking for what your palate likes and not necessarily what the “perfect” scientific way to do them is.


      • Thanks a lot for your help, I’ll continue with 2 raw potatoes (about 45 g RS then) per day, as well as some vegetables.

      • Hi Tim, I would like to incorporate resistant starch into my husbands diet who has type 2 diabetes with the aim of reversing his gut dysbiosis (the root cause of diabetes).. Since he needs a low carb diet what do you think about the idea of fermenting raw potato in order to get rid of the rest of the digestible blood spiking sugars..? Also are you absolutely certain of the percentage of resistant starch vs digestible starch in raw potato..? Thanks, Kee

        • I think fermenting a raw potato will actually do the opposite of what you want. It will be pre-digested and easier to absorb in the small intestine.

          A raw potato, however, should not spike BG much if any. There is no easily digested component in a raw potato. I once ate one full pound and check BG for 2 hours afterwards at 15 min intervals, there was no more than a 5 pt rise.

          Try it on yourself first, you can use his BG monitor. When you see it does nothing to you, try it on him.

          Yes, I’m absolutely sure on the percentages. For the most starch content, chose a baking potato (Russet). But the RS percentage of all potato starch is exactly the same. 64% when measured mechanically by an official fiber lab, 80% when measured in a live person.

      • Incredible! I’m glad the issue of eating raw potatoes came up and to see Tim’s response. I used to eat raw potatoes as a child – my grandmother used to hand me pieces while she was slicing them for cooking. I am pleased to start eating the raw potatoes again knowing the benefits of RS, Thanks again, Tim!

      • For all you raw potato lovers out there, there is a Japanese food comprised primarily of raw grated potato. Personally I find it disgusting, but my Japanese friends love it!

        Also, I’d like to hear more about the high levels of KPNA in honey that was mentioned.

        Good discussion, people!

        • KYNA in honey: http://www.ncbi.nlm.nih.gov/pubmed/18231708

          “The highest concentration of KYNA was obtained from honeybee products’ samples, propolis (9.6 nmol/g), honey (1.0-4.8 nmol/g) and bee pollen (3.4 nmol/g).”


          “Kynurenic acid (KYNA) is an endogenous antagonist of ionotropic glutamate receptors and the alpha 7 nicotinic acetylcholine receptor, showing anticonvulsant and neuroprotective activity.”

          This is all ‘brain stuff’. Just another tiny micronutrient that doesn’t factor into our Carb-Fat-Protein view of the world.

          I doubt this means you should eat a gallon of honey every day, but it does indicate that honey has some magic hidden in its sticky sweetness.

          • Interesting to note that this anti-inflammatory kynurenic acid (KYNA) is found not only in potatoes and honey, but also:
            “in some herbs regarded as herbal medicines when it comes to the digestive system: St. John’s wort, nettle leaf, birch leaf, elderberry flower, and peppermint leaf.”

            “KYNA was also found in leaves, flowers, and roots of medicinal herbs: dandelion, common nettle and greater celandine.”


            So potatoes are really in a good company!

            I would love to see or discover more research papers on the effects of these KYNA rich foods and herbs in inflammatory and other disease conditions and their possible relation to tryptophan, serotonin and melatonin metabolism (KYNA is a tryptophan metabolite).

            • These minor constituents interest me way more than the total carbs! Even the so-called toxins (saponins, solanine and choconine) seem to have human health protective qualities!

        • I LOVE the raw grated Japanese yam(?) called either Nagaimo or Yamaimo. Grated it’s called tororo as Tim mentioned in one of his comments. When grated it gets super slimy. Put it over rice and top with a little soy sauce, sliced green onions and crushed nori. Then slurp it up with some chopsticks! You can also top it with minced umeboshi (Japanese salted plum) or sliced shiso leaves. It’s addictive. Really!

      • I love raw potato and am wondering what size of potato in inches or ounces would be the equivalent to 100 g. Thanks.

        • 100g = 3.5 oz, or potatoes that would be 4 or 5 to the pound. That’s a very small potato, a little bigger than a golfball. Play around with the scales next time you are at the supermarket, they won’t get mad at you!

      • Hi Tim,

        Thanks a lot for sharing all of your wisdom – its really appreciated!

        Do you have a link to studies showing the range of RS2 in raw potatoes?
        If we assume its in the range of 60-80% of the starch and the starch content is 15-20g/100g would that really mean that I can subtract 9-16g from the carb count as it will not be digested? If that’s the case then potatoes are almost a low carb food.
        I can easily eat 500g of raw potatoes for dinner but that would actually only give me around 30g of usable carbs? Can it really be true? 🙂

        • CalorieKing.com shows 500g of potato to be 105g carbs w/11g of fiber. That’s eaten hot. Cool it and you’ll get an additional 25-50g of RS. The RS and fiber can be subtracted from total carbs to get a net carb value of 44-69g. Plus 12g or protein!

        • CalorieKing shows 500g of cooked potato to have 105g carbs and 7g of fiber. Cool it down over night in the fridge and you can add 25-50g of RS to that. Subtract the fiber and RS and you’ll see approximately 45-70 net carbs.

          • Thanks Tim!

            But if I’m eating the potatoes raw and up to 80% is RS then I’m possibly only getting 20-30g of digestible carbs, right?
            That said, even when cooked and cooled its still a lot of RS and not much digestible carbs. Moreover, cold potatoes are an underappreciated food 🙂 (even though you can reheat them without losing much RS).

      • I’ll just add a word of caution on raw potatoes.

        I don’t have a nightshade intolerance, but a few months ago I ate half of a raw potato that was flooded with solanine and paid dearly for it. It was not fun. 6 hours after ingestion I felt like I had been poisoned and needed a good dose of activated charcoal. Luckily, things settled down after that.

        If the peels have green under them — from either prolonged or improper storage — it’s usually best to just toss the potato (although, you could safely extract potato starch out of it). Once the green and eyes are there, solanine can flood into the potato flesh, so peeling those green areas will do nothing.

        Secondly, if you notice a burning sensation in the back of your throat as you chew on the raw potato, that’s the solanine/glycoalkalids you’re sensing. It’s your body telling you that something isn’t right. Spit it out and save yourself the potential trauma.

        As Tim points out, raw (fresh) potatoes are great, if tolerated. And trace amounts of glycoalkaloid nightshade toxins may in fact be very good for you, as they are believed to offer anti-inflammatory, hypocholesterol, anti-fungal, anti-bacterial, anti-cancer and anti-viral properties, as this study explains. But, That same paper also offers a stern warning on the dangers and complications when too many glycoalkaloids are consumed. It’s not all fun and games. The dose makes the poison. And sometimes glycoalkaloid issues — such as joint pain — can take weeks to develop, and they can take weeks to clear.

        So, please use caution. Eating raw potatoes is not ideal for everyone.

        I will say that one’s ability to consume raw potatoes is likely tied to their gut health. Gut bacteria can help metabolize glycoalkaloids (perhaps into some beneficial metabolites). Therefore, some people may gain or lose their nightshade tolerance over depending on the state of their gut health.

        And, for those who enjoy a Paleo perspective on eating raw potatoes, ancient Andean Indians did in fact eat raw potatoes with mud dressings and dirt to absorb excess glycoalkaloids. Though, it’s worth pointing out that their potatoes likely had far more glycoalkaloids than our wussy domesticated potatoes do. 🙂

  15. Dr. Nett – I’m a fan already! Great article, this is exactly why I have been talking non-stop about RS for nearly two years now.

    Alice – Just my take, but if you experienced headaches and insomnia after eating a bit of raw starch, you have serious gut dysbiosis whether you were feeling it or not. Everyone should be able to tolerate RS, it’s a foundational fiber, one we evolved on, and the fiber found most abundantly in nature, yet sorely lacking from our diets.

    Initially, gas and bloating may be a concern for most people with relatively good guts, but dose and time will clear this up. Headaches, joint pain, diarrhea, insomnia, and other major symptoms are all indicative of poor gut microflora.

    I’ve come to the belief that 4TBS is a bit much, and 1-2TBS plus lots of other fiber is better.

    • Thanks Tim. I get insomnia and restless legs syndrome from RS, but also from eating too many high FODMAP foods, so I know SIBO is a big issue for me at the moment.
      In the meantime, can I get butyrate from consuming ghee? Is it as beneficial to the colon?

      • Sorry, butyrate for the colon has to come from fiber-degrading bacteria. Lots of studies show that dietary butyrate doesn’t make it to the large intestine, it’s all absorbed as fat in the small intestine. The only thing that comes close is butyrate enemas or specially coated pills, but I doubt you can find these at Wal-Mart.

        Follow Chris’s advice for removing SIBO, and keep trying! All fiber is a FODMAP. People get too wrapped around the term and think they need to avoid them all. If you are forming turds, you are ingesting a FODMAP of some type. You maybe need to avoid allergens more than FODMAPS (dairy, wheat, eggs, nuts, shellfish, etc…). Find a way to eat that keeps you regular and feeling good! Avoiding foods until the list is four feet long is not the right approach. Elimination diets are great to figure yourself out.

      • If you aren’t tolerating FODMAPs, try cooked and cooled white rice. It has more “non-resistant starch” than pure raw potato starch, but I’m finding that it does not raise my blood glucose significantly and does not knock me out of ketosis. Test, test, test, as your mileage may vary.

        Rice pasta is essentially retrograded already, and I am tolerating that well. Make sure there’s no wheat flour in the ingredients, tapioca flour is OK, too.

    • Thank you Tim, is adapting of gut flora also one of the reasons one gets gas after ingesting dried fruit, which I love?

      • Possibly. Could also be from fructose malabsorption. I used to have issues with that–pears were the worst. Since starting RS almost 2 years ago, I have no more problems in this area.

        Dried fruits also contain super high levels of sulfur, usually. Some people have issues from sulfur.

      • Timing makes no difference from what I’ve seen. Possibly taking it in two doses during the day might have benefits over one big dose. I usually just do one big dose. Once it hits the large intestine, most fermentation of RS is done in the cecum and from there it slowly spreads out. One reason for taking RS alongside another fiber, like psyllium husk as mentioned by Dr. Nett, is that the fermentation products are more evenly spread throughout the colon.

        Until very precise studies are done, just do it however you feel comfortable.

  16. What about people who experience headaches and even insomnia when using potato starch? I had no GI distress whatsoever, but I had to stop it because of the aforementioned effects.

    • Same for me. I have bad leaky gut, shady bacteria and inflamed intestines. Potato starch causes me hypoglycemia, insomnia, headaches and overall weakness.

      It would be very interesting to hear opinions and experiences on how to proceed, when RS and prebiotics cause bad side effects. Chris said on a podcast that prebiotics are absolutely crucial in restoring healthy gut flora. Will the good guys take over if RS is consumed long-term or will the situation just get worse?

      • About 6 months ago, I was diagnosed with leaky gut, etc, resulting from some back-to-back antibiotics. I started probiotics, made some dietary changes, and began making progress, with side effects that after some research, I suspected the hang up was the lab-created prebiotics included in the probiotics. After a few experiments and some further reading, I switched to a probiotic that did not contain any prebiotics, inulin, fructo-stuff – and I was back on track and making good progress. I’m doing well now. From what I’ve read, once the digestive system is healed and functioning efficiently with a good population, prebiotics might very well be easily added without any repercussions. But I’ve also read that for some people, prebiotics – in the form of chemically made prebiotics under the name of fructo-stuff – will not ever be tolerated well. Also – this potato starch? I called Bob’s Red Mill and I’m not so sure it is a good thing. They don’t sell that starch for people to eat straight out of the bag. They used high starch potatoes, but they use a variety – including the high starch floury type potato which is NOT high in resistant starch, only amylase – which most of the potatoes they use are. And, they are NOT organically grown potatoes. They buy from conventional farms – those farms that use pesticides. And, remember that potatoes are on the “Dirty Dozen” list. So….

  17. So, you could add in potato starch on a ketogenic diet? The nutrition label says the total carbohydrates are 10, with no listed fiber.

      • Tim can u direct me to a site where I can contact you direct [abt raw taters] ? tnx Taterlover

      • My understanding is that potato starch as Chris points out is cooked and cooled in order form resistant starch.

      • Tim,

        Then if I understand this right, Bob Mill’s unmodified potato starch will not spike blood insulin, therefor since I am doing Kiefer’s Carb Nite, on VLC days I can eat a couple of tablespoons and the carb amount won’t put me in jeopardy of exceeding 30g of carbs?

      • You aren’t telling us we should eat raw potato starch are you??
        I have used it as a substitute for flour and corn starch in baking , ie cooked

        • What? That’s crazy! Eating raw starch is known as Amylophagia, a mental condition:

          (from Wikipedia)

          “Amylophagia is a condition involving the compulsive consumption of excessive amounts of purified starch. It is a form of pica and is often observed in pregnant women”

          “Amylophagia arises from a combination of biochemical, haematological, psychological, psychopathological and cultural factors. Many say that they are physiologically compelled to eat starch, and starchy things, because they enjoy the taste, texture or smell while others say that it helps relieve stress and makes them feel calmer. It is also believed that it be a result of a nutritional deficiency. Although the cause of Amylophagia is still unknown a number of these factors may contribute to its development.”

          But then again, same Wiki article:

          Health Benefits –
          “In their raw and uncooked form, small quantities of green banana flour, green plantain flour, unmodified potato starch and Hi-maize® resistant starch, are highly concentrated sources of resistant starch — a dietary fiber with strong prebiotic properties. Resistant starches are not digestible by humans and are fermented and metabolized by gut flora into short chain fatty acids, which are well known to offer a wide range of health benefits. Like most dietary fibers, resistant starch consumption has been shown to improve blood sugar, glucose tolerance, insulin-sensitivity and satiety. However, it should be noted that most published studies suggest that consuming more than 50 grams of resistant starch per day offers no additional benefits.”

      • Tim a interesting question, i have eaten raw potatoes off and on all my life, is that a RS? Is it healthy? Or bad idea?

        • Some traditional cultures still eat roots/tubers lightly roasted (~5 mins) on an open flame, which would mean the interior is still pretty raw and loaded with RS. IMO, this is the closest to how our ancestors likely ate them. I’ve done the same with cassava root on over the gas stove and also cooking thick slices on a George Foreman-like grill. Purposely undercooked them. French fry like taste. Perhaps a bit dryer. I like it. FYI, fresh cassava has much less water content than potatoes and starch breakdown needs a wet cook, so there ya go. Dry cooking starches creates some other additional prebiotics. Paleo man was all over dat.

          • Some cassava cultivars are fine to eat raw. Others are not and those are the ones used to make cassava starch and flour. And yes, the processing removes the toxins.