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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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    • Well, that’s focused primarily on supplementation only, or supplementation without enough fiber (soluble and insoluble_ present as well.

      And it’s after exposure to a significant carcinogen which may not happen that often.

      I’m merely pulling out 2 key points from the linked article, but am mentioning it here in case someone just passing through doesn’t have the time to click through.

      I’m on the fence about supplementing RS, but can see taking some while keeping up on veggies.

    • To summarize the link you gave, trying to get resistant starch from supplement is bad.

      But.. getting resistant starch from whole food, like legumes, cooked and cooked and cooled sweet potatoes, brown rice, oats etc.. is good.

      Legumes, such as black beans, are considered strong anti-angiogenic/antitumor foods.

      The resistant starch and butyrate produced when eating are just two of the many potent anti cancer phytochemicals in whole legumes.

      The bit of phytic acid left in legumes after cooking also has anticancer properties, and eating these foods with vitamin C rich foods, such as fruits and red peppers, boost absorption of iron (X4), overcoming the bit of iron absorption inhibited from phytic acid.

      • Thank you for pointing this out. I’ve been troubled by the paleo community’s over-villainizing of phytic acid. By all means, soak and sprout to reduce phytic acid. But as you say, it also has beneficial qualities, and you wouldn’t want to completely eradicate them from your diet.

    • Of course you had to ignore the fact that resistance Starch based stuff like rice and noodles (Asians), corn and peas (Mexicans), and potatoes (Europeans) have been eaten as A staple and kept Poole healthy and satieted for no doubt thousands of years!

      I agree getting it in powder form is not the best but it is only the tremendous ignorance around Starch based vegetables in the paleo and low carb community that stops people adding these items to their meals. When they are consumed in their WHOLE form they are satieting and stop cravings for sweet foods or snacks. whole civilisations have used them as a diet staple for so long.

      What I dislike is the bashing of starch based carbs as part of the meal. They kept me trim in my younger years. Only since some idiot nutritionist told me I have a potato intolerance have I gained 20 KGs! And increased my blood pressure, and risk of diabetes toboot!

      Do your damned research and note that the nutrients in potatoes as a whole food are anti cancer not Pro cancer. They contain fat, protein, carb, all the amino acids, vitamin c, high potassium, B6 (which is why they stimulate tryptophan, then seratonin and melatonin) making them the best anti depressant Mother Nature created. Not to mention high amounts of hyaluronic acid which is great for skin, bone, anti aging in general.

      Of course you will ignore all that and bang on about cancer forgetting high protein diets and a high increase of meat and fat ate what cause inflammation and cancer. GO you!

    • In the description of four types of RS (above near the beginning of the article), Chris states that cooking causes changes in the starch making it digestible to us, and removing the resistant starch. From this I conclude that the fried green bananas may be tasty but useless for trying to incorporate RS in ones diet.

  1. I have an ileostomy and maybe sibo. I fight hypotension and low energy. How shall i eat. Does R S. do me any good with no colon?

  2. I recently read a report that modified potato starch caused tumors in 88% of mice that were given this form of RS for 20 weeks. I have been mixing it with water daily. Is this an accurate report?

  3. I love this article. So helpful to understand about prebiotic and resistant starch. I understand that beans have a lot of resistant starch but not much mentioned in the article. We all need to take more of resistant starch.

  4. I started taking RS a week ago. Around the same time I started using MCT oil in my tea. Now I am experiencing adrenal fatigue. Has that happened to anyone else?

    A little bit about myself. I was on the paleo diet for 11 months and now I’ve been on a the ketogenic diet for a few months.

    • Joan, I would look at reducing the amount of MCT oil you are taking and see if the issue resolves itself. I had a similar reaction but once I lowered the dose, the issue went away.

      • Gut microflora have metabolic enzyme that make electrolytes more bioavailable. Your body craves electrolytes. My experience observing loved under going ketosis has not been a good experience. No….in each case it was unique and not done voluntarily. I will leave it at that other than its an amazing way the body attempt to survive.

  5. I started using resistant starch about a week ago. The first time I felt some inflammation and it subsided the next day, and now I am experiencing adrenal fatigue. Has anyone else had that problem?

    • Try the whole food form. Potatoes, sweet potatoes, etc.

      I have SIBO and initially I had a bit of bloat (went on a predominantly Potato diet for a week) but that has settled leaving me less bloated, happier in mood, relaxed and content. I also have more energy than I did previously. That’s coming from someone who was told she had Potato and banana intolerance. I tried a day on bananas. Worst bloat I’ve ever had and felt as you describe. Being on Potatoes as helped. Added in some parboiled Rice recently and again bloated and eyes felt sticky and dry the day after.

      You will need to play around with different starches to see which one suits you personally by the sounds of it. For me I preferred going to one food for a few days as in tests it was noted I had so many food intolerances that reducing that to one made a lot of difference.

      In my twenties I lived on potato based meals and has no issues. I could never gain actually. Skinny as. Only in times when I have tried Atkins, or lowering carbs and ditching them have I caused inflammation. I believe it was because I stressed my adrenals. In my 50’s I have switched back to my previous diet which now only consists of limited foods. I have ignored all advice about a varied diet. Seems to me a few staples sees me healthier.

      If you were adding unmodofied potato starch, perhaps try whole potato instead as their are so many nutrients in them. I’ve had five children. I seldom has stretch marks and always my figure snapped back to pre pregnancy until I stopped eating potatoes and then there was a 20kg weight gain and sadly masses of stretch marks. I believe the high hyaluronic acid helped my skins elasticity in hind sight.

      • This information was very helpful. This has been my experience with potatoes, too, as well as a limited diet of organic real food. We grow our own potatoes and that certainly makes a difference.

  6. Article isn’t clear.
    What are you supposed to do with a potato, cook it or eat it raw? My mashed potatoes are usually cooled down by the time they hit my plate and mouth

    If cooking renders the RS digestible then what do you do? How many green bananas, plantains can you eat in one sitting?
    Legumes cause gas.

    I have a gut feeling (excuse the pun) that the fancy new name, RS is another name for what we used to call fiber.

    I doubt I am going to lose any weight from eating cooled down mashed potatoes, bananas and beans.

    • You can google, “how to make starch resistant potatoes” and get details on what to do with the potatoes. Basically, all you do is make potato salad and refrigerate it overnight (minimum time). Do not reheat it after that. Just eat it cold.

      • Probably the worst thing you can do. It doesn’t settle at all. Same with “UDI’s” products, you are replacing a lectin with a lectin

      • Don’t eat it raw. There are natural phytotoxins like glycoalkaloids that could make you sick. Plus they taste icky. I doubt our root n” tuber eatin’ ancesters did that anyway. They might have though. Its possible the good gut bacteria may break down toxins…..anyway the fire invention thing seemed to take off. When cooking the polymers open up to make them more palatable. Then polymers of starch anneal when they cool. Sort of like DNA, when you heat it, the double helix break away from each other and re-anneal when it cools. When you cool some starches, you get lot off double helix formation too!. That make it more difficult for enzymes to break it down. I had a student go vegan. Told him to watch is gut microbiome. He pulled out a boiled potato with the skin on and took a bit. I was impressed, He must have listened in class.

    • Ajax, I disagree; this article seems very clear. It outlines the issues, the causes + effects and then tells the reader what they need to do.

      What it doesn’t do is hold the reader’s hand and walk them through a selection of recipes and preparations for each example.

      What you (as the reader) have done is dismiss this article because you’ve decided that it doesn’t give you enough information to convince you. So, that’s on you (and your gut, for what that’s worth). But don’t blame the article for your decision just because the author hasn’t bent over backwards to draw you a complete map.

      Anyhow, just my two cents. Good luck with your take on science and health (and your gut)!

    • Please could someone tell me what the difference is between modified starch and resistant starch

    • Please could someone tell me what the difference is between unmodified starch and resistant starch

    • Pam, you’re not serious, are you. The FDA does not supporting any health building activity by anyone. Notice in this ginormous article and comments section that your mention of the FDA is the only mention of the FDA.

      • Right…FDA is so far behind the times they still recommend 6 – 7 servings per day of carbs and very low fat intake, which is completely the opposite of what we all should be doing.

        • I really wanna comment on that. I don’t care about the FDA, but I do care about people saying that we ALL should eat a certain way which is NOT true – or rather I care about the people who believe that (ppl with adrenal disorders trying to get on a keto diet because it “has so many health benefits” etc). Maybe you didn’t mean it exactly like that and you just wanted to point out that low fat is problematic for almost everyone, so don’t take it too personal :).

          We are all different, have different genetics, a different daily schedule, different sleep, different stress levels and ability to deal with stress, different levels of health/conditions (!), different goals (high spirituality vs meat), different weather/climate/seasons (mild, warm, cold, hot,…), different acitivity levels and so on and so forth….therefore we simply can’t have a one-size-fits-all, neither for macronutrients and micronutrients, nor for food selection.

          All the best,

          • Thomas, you’re right on point. That seems to be my mantra these days “we’re all different.” We can guide, help and advise each other but at the end of the day, we need to determine what works best for our own unique individual being.

    • FDA only approves drugs, hence the D in FDA. Potato starch is a food product used for thickening soups etc. You can buy it on Amazon.

  7. I would like to know the difference between unmodified potato starch and resistant starch. I ordered Bob Mill’s Resistant starch and received the Unmodified one.

    • That’s the one u need that is un tampered with lol also u can just buy it at the grosery store most carry it now. 🙂

  8. Hi! I have a gotten some problems ever since I went over the top on resistant starch. I lift weights and eat a lot of food. I go low carb during the day and I take my starches in the evening. I’ve eaten about 3500 calories. 50% fat, 30% carbs and 20% protein. For fats and protein i’ve eaten mainly meat and fish, dark chocolate, hazel nuts, coconut oil and large amounts of butter.

    I had for months eaten between 1 and 2 pounds of potatoes every evening, cooked, but re-heated in the microwave. Sometimes alternating between Sweet Potatoes and rice as well.
    I have to add that in for breakfast I ate approximately 1,5 pounds of vegetables and strawberries. Tomatoes, carrots, broccoli and the like, everything cooked.

    I did not have a problem with this diet. I ate approximately 6 pounds of food. My belly was flat and fine.

    Than I read of resistant starch and went over the top. I started with 175 grams of rolled oats and two big greenish bananas in addition to 1,5 pound of cooked cold potatoes in my evening meal. I got a distended stomach, I assumed it was bloating or constipation. But I did not feel constipated, no problem going to the bathroom, actually better than before.
    I thought it must be the oats and bananas that was giving me the distended belly, so I cut those out and added even more potatoes, this time approximately 2,8 pounds, cooked and cold. It did not get any better, I still had the distended stomach. So I figured it must be the resistant starch.

    So for the last few weeks I’ve cut out all the vegetables and potatoes and gone stricly low carb with meat, fish and oils but my stomach is still distended even after cutting the overall food intake to under half.

    Any viewpoints on why I could be having this distended stomach? Have I gotten a problem with my digestion? I’ve had bloodwork done and they were fine across the board and the doctor says it’s probably not cancer or ascites and I should just wait it out for now.

    After a quick count I ate around 50-90 grams of fiber, and between 40-80 grams of resistant starch.

    • I’m curious about why you started using RS in the first place if your belly was ‘flat and fine’. I don’t think anyone ever recommended replacing vegetables with RS – you were probably getting the right amount of fiber in your diet from all those you were eating. Why don’t you go back to your original diet without the RS and see how you do?

  9. Let food be they medicine, let medicine be thy food.

    Taking spoons of resistant starch is a BAD IDEA. Find the RS in your food, not in concentrated “supplementation”.

    • @jeremy

      Yes, “supplementation” is SO evil. And your “BAD IDEA” argument is so scientifically sound.

      How about stop driving your car or taking public transportation…or riding your bike. Let thy feet be thy motion. Also, stop breathing in all these modern day toxins. Let thy clean air be be your breath … oh wait, there is no clean air left. And do not let cement and artificial fur pass under your feet. Let the grass and shrub be thy passing and dwelling.

      And stop eating all that food that’s not 100% natural … oh wait, there are no natural foods left. Shucks.

  10. Ok, I understand the concept of these certain foods are suposed to resist digestion. But does the body get any energy and nutrients from them? Or does it all just fill your stomach and pass through?

    • modified starch contain high mount of amylose than amylopectine that are major part of starch .Because amylose not easily digest by amylase enzyme during intestinal passage that,s why starch called resistant starch
      resistant starch may be modified starch but it not necessary that every modified starch is a resistant starch.
      resistant starch provide our body short chain fatty acids like butyrate that prevent our body from cancer.

  11. What is known about Inulin plus RS 3. Can you explain a little bit of all the details?

  12. I don’t understand how much one has to cool potatoes or rice, etc to get RS benefits. I bought David Feders book, The Skinny Carbs Diet, and many of the recipes seem like regular recipes. Will cooling something for just 15 minutes make a difference?For example, Ratatouille Lasagna cools for 15 minutes. It’d still be quite hot out of a 350 degree oven. Penne Pomodoro has no cooling time. Id appreciate any help. Thanks, Lynn

    • Lynn, I’ve read that you should refrigerate them for 12 hours before eating and then don’t reheat them too much – the cooler the better.

  13. with the Bob red mills Potato starch can you heat it above 130 degrees and still get the effects of resistant starch? I want a resistant starch i can bake with.

    • No you can’t. Heating it unwinds the starch molecule and makes it digestible. You can bake with it, just like corn starch. Just not as powdery.

  14. Hello, I’m just jumping on the bandwagon here of RS. I have been taking the potatoe starch morning and evening almost two weeks now. I have been low carb about three years, so this is kind of scarey nut exciting at the same time. I basically have been eating the sommersize way, keeping carbs separate from protiens.
    I understand eating the rice, potatoes etc cooked and cold changes the strutcture of the starch.
    Question is.. Is it ok to eat protiens/fats with the RS????

  15. are raw asparagus considered a resistant starch, or a prebiotic, or? are there any herbs or spices that fall into the resistant starch category?

    I eat raw asparagus, often. It helps a lot with gastrointestinal problems; also, fresh ginger and garlic.

  16. Recently purchased Bob’s potato starch and am interested in losin 25 lbs. I saw it on Dr Oz. how would you begin?

    • I’m starting like you. I saw that same show probably. Go to sprouts and get the potatoe starch. If you have a really tyically sensitive body, start with one teaspoon in COLD water. Take at night would be a good start.
      I started with 1 tablespoon, did fine, then on to two tbsp. Now I do 2 tbsp, morning and evening.
      Remember always in cold water. Then you can move onto the cooked and chilled actual foods.

    • Dr. Mark Hyman, who has been on Oz many times recommends in his book “Eat Fat Get Thin”, to start with 1/4 tsp. In 8 oz. of water working up to 1-2 Tbsp. per day. You can also Google ” How to take potato starch”. If you are looking to lose 25 lbs. get Dr. Hymans book, I got it from my library.

  17. I understand that dehydrating the green plantains keeps the resistant starch intact, however, all I have is my oven. The lowest setting is 170 degrees. Is this still too high to keep the starch intact? I dried them overnight then ground the slices to a fine powder in my food processor. Plan to use it sprinkled on other foods. Any thoughts on this approach?

    • My oven goes lower and still stays on when I move the temperature indicator below the lowest setting on the dial. It wiIl go even lower, but I feel that I can safely get it down to about 145 degrees F. Be careful, though if you have a gas oven. You may want to choose another method. You want a good margin of safety so that your oven doesn’t go out. Then I leave the door open and use a good oven thermometer to figure out how far I have to open it to get it to the right temperature.down to about 125 degrees F. Or just leave the oven at 170 degrees and leave the door open. Great in the winter, you don’t need the heater so much. You can also clear out a cabinet and either place a few seed mats in there (for keeping potted seedling starters warm) or a few electric heating pads.