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
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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Very interesting article. Any idea how long it takes to feel the effects of the increased butyrate production, assuming you’re eating 15-20 grams of RS per day?
Overnight.
The results for BG control and sleep usually happen the first time you try it. Some of the other benefits may take a bit longer, and if you have a terribly dysbiotic gut you may not see benefits at all.
The gas associated usually goes away in a few weeks as your gut flora composition changes to use all the byproducts of the RS fermentation.
Start with a small dose, 1tsp – 1TBS, and work your way up. I don’t think there’s a need to go over 2TBS if you are also eating lots of the food discussed here.
Thanks, Tim. You mentioned that if you get a lot of digestive discomfort it’s a sign of an unhealthy gut. Can we assume that the reverse is also true, i.e., no digestive disruption = healthy gut? I’ve been eating a whole raw Russet potato now for three days in a row. I cut it up and have it with olive oil, salt, and pepper – it’s not bad! No digestive issues so far.
If you can eat raw potatoes, you most likely have a pretty solid set of gut bugs. Glad to hear it!
You should see if you can find Jerusalem artichokes and try those raw. I’ll be curious how you do with inulin.
I like raw potatoes as you described. Vinegar gives them a nice kick, too.
I’ll look for them! I’m blessed to live three blocks from an excellent natural foods co-op. One final question, about potato flour. The brand I have (Ener-G) lists the ingredients as “pure potato starch.” But you’re saying potato flour and potato starch are not the same thing? Is there a reason to avoid potato flour if you’re not eating it for the RS? For example, as an alternative to gluten-containing flours?
If it says ‘pure potato starch’ it should be OK to use. Check to see that it settles to the bottom in a glass of cold water.
Potato flour is whole, ground, dried potatoes. Potato starch is the extracted starch…big difference. Sometimes I guess they use the terms interchangeably, but incorrectly.
Potato flour is fine for certain applications, ie. GF baking
I found Jerusalem artichokes (they are called sunchokes here). Very tasty and no digestive issues!
I somehow missed the explanations as to why or how RS improves sleep. I’ve definitely noticed myself sleeping better since I’ve been using it, but I have patients with very stubborn insomnia, and I’m considering recommending RS, but would like to have a better sense of how it works for sleep. Thanks in advance!
Do any of you have any advice on RS for Lyme patients?
How about on RS for a combination of Lyme, SIBO, dysbiosis and myriad of other infections all combined?
Thank you to all of you who are sharing your invaluable advice.
I’m aware of some CFS patients who tried supplemental Resistant Starch. You can read about their experiences here.
Some of the experiences were good. Some were bad. They are a tricky bunch as they tend to have trouble clearing endotoxins as pathogens get killed off. And this tends to result in inflammation. Sort of like taking a step back every time they take a step forward.
Some of them had more success with Larch Arabinogalatan (LAG), which is an immune-stimulating fiber that requires relatively tiny doses to have a big effect.
Incidentally, Chris uses LAG as a prebiotic with his own patients:
http://store.chriskresser.com/collections/blood-sugar/products/prebiogen
That’s a darn fine blend. Add a scoop of your own potato starch and really make it special.
So, does the prebiogen have stuff lacking the PS? In other words, would the average person with some gut issues benefit from this product when cheap PS works just as well?
Prebiogen feeds different species and does different things than PS. You can consider PS to be one of the staple foods of your microbiota (literally the rice and potatoes of your gut bugs). Your gut bugs can eat a lot of them too.
Prebiogen contains Larch Arabinogalatan (LAG) and beta glucans, both of which have immune-stimulating effects in very tiny quantities. You typically only take a teaspoon or so of those immune-stimulating fibers — but they aren’t intended to feed your entire microbiota.
Thank you, Duck. That is really helpful
No specific advice, but I think the current rise of Lyme disease is more a statement of our guts than an increase in ticks.
Get a good gut and avoid Lyme disease. I read recently the Lyme disease causing bacteria, Borrelia burgdorferi, has been around for billions of years, but we’ve only recently been having problems with it.
So if you get your gut back in shape, are you then able to handle an existing Lyme infection, or by then is it too late?
Is this too off topic?? I wondered if Lyme was similar to other gut pathogens that the body starts to manage well once gut health is restored, or if Lyme is somehow more resilient.
Thanks.
That’s a good question. If I had a Lyme infection, I would definitely want to concurrently work on my gut, especially if treatment involves antibiotics!
A good gut and immune system should, theoretically, be able to stave off Lyme.
Once the spirochetes are embedded, it’s a bit more complicated than gut health. You’ll want to read this:
RHR: Diagnosing and Treating Lyme Disease
Good luck to you.
Oh, and Diana… Please don’t construe this as medical advice (I’m certainly not qualified to give any), but you might want to look into this before trying any long term antibiotics.
Tim, Duck,
Thank you both so much.
Here’s another lead for you, Diana. Do your research. Read the reviews as it suggests you need to take it with Burbur. No promises.
Thank you Duck. It looks hopeful. I will try it.
So I just started experimenting with fermented foods. I added raw potatoes to my kimchi. They turned out great…. and nice and soft. So would that be an extra dose of prebiotics? How does fermenting potatoes fit in with this article?
I’m inclined to believe that fermenting potatoes reduces the RS, but, I also think that fermenting potatoes is a very healthful way to eat them. They are still full of great fiber, some RS, and probiotics.
Keep on doing it!
Just to confirm . . .
If I make bread with potato starch in it, and then keep it in the fridge overnight, the RS amount that was “baked out” will “return,” yes?
Not quite that simple. Let’s say your bread recipe calls for 1 cup of potato starch, which weighs 200g (trust me, I just weighed a cup!).
This 200g of PS has approximately 140g of RS (RS type 2). When you cook with it, it completely disappears, but allow it to cool and it will ‘retrograde’ into RS type 3, but at a much smaller amount. The 200g of PS will provide maybe 10-20g of RS3.
If that makes a loaf of bread with 10 slices, each slice will have 1-2g of RS.
If you are doing this JUST to get RS, it’s not a great plan. If you do it anyways, the RS is a bonus.
Hope that helps!
I thank you for all this invaluable information and explanations. I really appreciate your taking the time to answer all of us.
Yes, that helps. Thank you!
Using this info regarding resistant starch (from the awesome article) can I let my children have a daily greenish banana to ensure they’re getting their resistant starch? I’ve avoided this thus far as we’re on the GAPS as my son on high dose steroids for nephrotic syndrome (auto-immune disease?) Look forward to receiving some insight!
Jo
P.s my husband and I had our first teaspoon if green banana flour this AM!
Greenish bananas are a real food, eaten for millions of years by people of all ages. Why not?
My understanding is that bananas are not indigenous to Africa (nor the Middle East or Europe) and thus have not been consumed for millions of years, but “false banana” trees are, and the RS-rich pulp of the false banana trees, rather than the fruits, are favored.
So I understood, we should eat plantain flour, potato starch, and green banana flour raw? Like making pancakes out of that won’t work? Unless we cook it under 130 degres?
For max effect, yes.
Tim,
Your information here is invaluable. Thank you!
I have two questions I hope you can help me with. First, do different sources of resistant starch influence/feed different strains of friendly microbes? And if so, would it not be better to regularly consume RS from a variety of sources? I understand the convenience of potato starch and I use it myself; but does it feed only a few strains of probiotics?
Second question: is it best to take probiotics with food or on an empty stomach? I have seen it argued that the stomach is actually less acidic during a meal when food is present than in the very acidic environment of am empty stomach. What is the truth here?
Yes, different RS sources feed different sets of gut bugs so it is important, as you say, to eat more than just potato starch for your fiber needs. It seems in nature, the two biggest sources of fermentable fiber are inulin and RS2. These are not normally found together in nature in a plant or even geographically, but they feed a similar set of microbes when ingested. The microbes that ferment inulin and RS produce butyrate in copious amounts, but also leave behind scraps of the fiber for other microbes to eat. This is known as the ‘keystone and co-feeder’ effect.
Other fiber types are equally important, but found in much smaller quantities in nature. This is why it is ridiculous to rely in wheat chaff, psyllium husk or oat bran as Metamucil would have you believe.
http://www.metamucil.com/pdf/All%20Fibers%20Are%20Not%20Created%20Equal.pdf
Anytime you see a study produced by Metamucil… question it!
The other fibers, ie. gums, mucilages, pectin, beta-glucans, arabinogalactins, FOS, GOS, etc… are ALL important and should be consumed near daily by including a wide range of fruits, vegetables, nuts, and seeds in your diet. Bee pollen is also a great source of fiber. Consuming these ‘other fibers’ in a real-food setting also allows you to consume numerous micronutrients not available in a supplement, just as eating potatoes gets you the goodies not found in potato starch. Fiber supplements are great to boost intake, but a poor choice for all of your fiber needs.
Timing: How could you go wrong taking probiotics with a meal? That’s when they would have been consumed for millions of years. Also, take your RS supplement at the same time. Probiotic microbes can actually cling to the RS granules and get a protected ride through the small intestine. I’m always a fan of simulating natural, ancestral feeding patterns.
Hi tim
I have another question about tapioca starch. I just notice that my bag of Bob’s red mill tapioca says: “Tapioca flour also known as tapioca starch (and then it goes on on describing the process) is ground to a powdery fine granulation from the dried roots of the cassava plant”. You explained the difference between potato flour and starch. does that apply to tapioca as well? They seem to think that Tapioca flour and starch are the same. What are your thoughts on this?
Tapioca starch is just so all over the place I have a hard time recommending it. The papers all say it should have great RS, but there are also different manufacturing processes that may destroy in in some brands. Until more is known, I just have to say, ‘try it’ and see what you think. Some swear by it, some say it spikes blood sugar.
I am at a bit of a loss on tapioca starch. In theory, it should be b\very high (40-60%) in RS, on par with potato starch, but there are different processing methods some of which are said to destroy nearly all of the RS. Until someone markets tapioca starch that is labelled with the RS content you are taking a gamble. If you are doing it for glucose control and have a BG monitor, it’s easy to check. If you are just using it for general health and its your sole source of RS, you may be doing yourself a disservice.
I am on low carb diet. What if I eat a small peace of potato raw or unripen banana small portion ? Will it have any usable carbs? Will it give me the resistant starch I need? Is Prebiotic the same as thing as resistant starch? Is the resistant starch the same as non soluble fiber? Thank you
Raw potato and green bananas have negligible net carbs and a great RS content.
RS is a prebiotic, but not all prebiotics are RS.
RS is a form of non-soluble fiber.
I have found that using resistant starch, in the form of potato starch, has cause leg cramps to disappear. This occurred within the first week of taking it and worked when nothing else did, including using diet and minerals.
I don’t know if someone can explain about my symptoms with RS.
I was buying green plantain and drying them on the dehydrator and I was eating before meals and in the evening with the probiotics that Richard recommend.
I was feeling tired, sleepy nearly every day for a few weeks, then one day I decided to stop taking them and my energy came back again I was surprised. The other night I have 1 tsp with my probiotics and 1 tsp with my breakfast and all my symptoms came back again feeling tired, without energy
So I don’t understand how RS can work for someone with blood sugar problems when it really was causing the symptoms that I was trying to treat?
All I can tell you is that my blood glucose numbers improved significantly after I started consuming more resistant starch. The only way to tell for sure what effect you get is to measure with a glucometer.
I’m not sure if you have answered this already. I like to add tapioca starch to my warm cup of chicken broth in the am. What is the max temperature that the RS in tapioca can tolerate?
I had to Google for that one! Found this: http://www.thaiscience.info/Article%20for%20ThaiScience/Article/2/Ts-2%20determination%20of%20starch%20gelatinization%20temperatures%20by%20means%20of%20polarized%20light%20intensity%20detection.pdf
It says potato starch starts to gel (this is when RS gets detroyed) at 59C (138 deg F) and tapioca starch gels at 61 deg F (141 deg F).
Hope that helps! You’ll know if it gels right away, you will have a cup full of hair gel.
Thanks again Tim!
It’s my understanding that psyllium seed is the prebiotic fiber, whereas psyllium seed husk is insoluble fiber that actually damages the lining of the small intestine, forcing a repair, during which the intestine secretes extra liquid, which moves food along. Am I missing something?
I think that’s a Fiber Menace Fairy Tale. I’ve never seen anything to suggest that in actual studies. It’s more a ‘seems like’ theory.
Do we know if there are specific bacteria that affect colonic motility? And if we do – is there a probiotic that contains it?
Hi, I am on natural dessicated thyroid for my throid issues and also on the Paleo diet in order to keep Blastocystis hominus in control.
As much as I am disciplined, I seem to be gaining weight, feel tired, crave caffein and find life a challenge still. I take Diotimaceus Earth, vitamins, and a mixture of ground flaxseed, psyllium fibre and chia seeds with my high probiotic yogurt each morning. Will this help with the resistant starch concept?
I feel that I am losing my battles.
You may need more thyroid and/or an adjustment in dosing such as taking 2/3 in the morning and 1/3 later in the day. The web site stopthethyroidmadness has many patient experiences with NDT if you haven’t visited it yet. If you’re still eating wheat, try avoiding it for at least a month because it can cause fatigue, at least for me.
The flaxseed and chia seed would not be a significant source of RS as far as I know. I started with 1 teaspoon of potato starch in water and gradually worked up to about 2-4 tablespoons/day or the equivalent in mung bean starch, green banana flour, cooked/cooled potatoes, cooled white rice, green bananas, or green plantains.
The combination of eating a primal/Perfect Health Diet, taking desiccated thyroid, eating zero wheat and resistant starch + other fibers and probioitics (including soil-based) has gotten rid of my decades-long fatigue, brain fog, and weight gain. It’s so worth figuring out what works for you. Good luck!
Im curious as to how much RS is in the following:
1) raw oats soaked overnight in homemade almond milk
2) homemade peanut butter made only with roasted/unsalted peanuts
Oats and nuts both clock in around 10-15g per cup.
Oats and nuts both have several different compounds that make them very gut-friendly, but come with quite a calorie/carb load, so eat them as you can to fit your dietary goals.
Thanks Tim.
What about the peanuts (legumes)?
This is a great discussion and lots of good ideas being shared. I’m just wondering from a paleo purist point of view, aren’t potatoes a no no? Also the carb content of potatoes is very high so it could totally blow out someone’s weight loss plan?
Happy to hear the experts’ opinion.
A potato is a real food item, eaten by people of the Americas in the paleolithic. You’d be surprised how many potatoes it takes to make 100g of carbs. One smallish, potato (200g) has about 37g of carbs. Undercook it to where it is still a bit raw in the center and the net carb count drops significantly.
Does reheating cooked rice in the microwave destroy the resistant starch?
Thanks
A bit, but not enough to worry about.
I get anaphylaxis from potatoes. Is there another starch I could use?
Banana Flour…there are a few on Amazon and at WeDo Gluten Free. This is a great source of RS when eaten raw, and also makes really good gluten free pancakes and other stuff if you are into that.
The RS content of banana flour is hard to pin down because of manufacturing differences, banana species differences and ripeness, but it will fall into the 25-50% range, which is pretty good. Lots of other good stuff, too, as banana flour is made from whole, dried bananas.
Any idea if RS can suppress some beneficial bacteria like beneficial forms of e coli? I have to avoid FOS because it can suppress e coli (my levels of beneficial e coli are very low) so I want to avoid the same issue with RS. Does anyone know?
I have been using raw potato starch and green banana flour (here in AUS) and seemed to lose some weight – yay 🙂
I think you are getting some bad advice. FOS is a prebiotic just like RS and all the others. It serves mainly as food for bifidobacteria and lactobacillus when they are present. Flourishing colonies of lacto and bifido will suppress e.coli to some extent, but I wouldn’t withhold food from lacto and bifido to allow more e.coli to grow. That just seems like bad advice.
The e.coli you have that will be considered ‘good’ is a small niche that finds a small foothold alongside beneficial bacteria. E.coli can easily turn pathogenic and can really thrive in a gut with high pH and low lactic acid levels. E.coli can survive a wide range of gut conditions, but will take over if gut diversity is poor.
I’m not a huge fan of FOS, so avoiding it is no problem, but don’t avoid all prebiotics just to grow e.coli. Set the stage by eating good food, prebiotics, probiotics, and living a gut-bug friendly lifestyle. The microbes will sort themselves out.
Tim the advice to avoid inulin to prevent suppression of E coli is from Bioscreen who are a stool testing lab in Australia run by very experienced microbiologists. Their advice may be right, my levels of E coli dropped after faecal transplants and I was taking inulin after the faecal transplants along with other prebiotics incl.RS.
I’m definitely not avoiding all prebiotics, just inulin. I am taking lactulose, some GOS occasionally plus RS in food.
thanks!
Tim, why aren’t you a fan of FOS, if you don’t mind explaining? Thanks!
Laura – could you email me at akman2014(at)live.com? We got some talkin’ to do!