Getting Starch to Take the Path of Most Resistance

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The Best Source of Resistant Starch

Resistant starch wasn’t discovered until 1982. Before that, we thought all starch could be digested by the digestive enzymes in our small intestine. Subsequent studies confirmed that there are indeed starches that resist digestion and end up in our large intestine, where they can feed our good bacteria, just like fiber does. Resistant starch is found naturally in many common foods, including grains, vegetables, beans, seeds, and some nuts, but in small quantities, just a few percent of the total. As I discuss in my video Getting Starch to Take the Path of Most Resistance, there are a few ways, though, to get some of the rest of the starch to join the resistance.

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta and potato salad can be healthier than a baked potato, but the effect isn’t huge. The resistant starch goes from about 3 percent up to 4 percent. The best source of resistant starch is not from eating cold starches, but from eating beans, which start at 4 or 5 percent and go up from there.

If you mix cooked black beans with a “fresh fecal” sample, there’s so much fiber and resistant starch in the beans that the pH drops as good bacteria churn out beneficial short-chain fatty acids, which are associated both directly and indirectly with lower colon cancer risk. (See Stool pH and Colon Cancer.) The more of this poopy black bean mixture you smear on human colon cancer, the fewer cancer cells survive.

Better yet, we can eat berries with our meals that act as starch blockers. Raspberries, for example, completely inhibit the enzyme that we use to digest starch, leaving more for our friendly flora. So, putting raspberry jam on your toast, strawberries on your corn flakes, or making blueberry pancakes may allow your good bacteria to share in some of the breakfast bounty.

Another way to feed our good bacteria is to eat intact grains, beans, nuts, and seeds. In one study, researchers split people into two groups and had them eat the same food, but in one group, the seeds, grains, beans, and chickpeas were eaten more or less in a whole form, while they were ground up for the other group. For example, for breakfast, the whole-grain group got muesli, and the ground-grain group had the same muesli, but it was blended into a porridge. Similarly, beans were added to salads for the whole-grain group, whereas they were blended into hummus for the ground-grain group. Note that both groups were eating whole grains—not refined—that is, they were eating whole foods. In the ground-grain group, though, those whole grains, beans, and seeds were made into flour or blended up.

What happened? Those on the intact whole-grain diet “resulted in a doubling of the amount excreted compared to the usual diet and produced an additional and statistically significant increase in stool mass” compared with those on the ground whole-grain diet, even though they were eating the same food and the same amount of food. Why? On the whole-grain diet, there was so much more for our good bacteria to eat that they grew so well and appeared to bulk up the stool. Even though people chewed their food, “[l]arge amounts of apparently whole seeds were recovered from stools,” but on closer inspection, they weren’t whole at all. Our bacteria were having a smorgasbord. The little bits and pieces left after chewing transport all this wonderful starch straight down to our good bacteria. As a result, stool pH dropped as our bacteria were able to churn out so many of those short-chain fatty acids. Whole grains are great, but intact whole grains may be even better, allowing us to feed our good gut bacteria with the leftovers.

Once in our colon, resistant starches have been found to have the same benefits as fiber: softening and bulking stools, reducing colon cancer risk by decreasing pH, increasing short-chain fatty acid production, reducing products of protein fermentation (also known as products of putrefaction), and decreasing secondary bile products.

Well, if resistant starch is so great, why not just take resistant starch pills? It should come as no surprise that commercial preparations of resistant starch are now available and “food scientists have developed a number of RS-enriched products.” After all, some find it “difficult to recommend a high-fiber diet to the general public.” Wouldn’t be easier to just enrich some junk food? And, indeed, you now can buy pop tarts bragging they contain “resistant corn starch.”

Just taking resistant starch supplements does not work, however. There have been two trials so far trying to prevent cancer in people with genetic disorders that put them at extremely high risk, with virtually a 100-percent chance of getting cancer, and resistant starch supplements didn’t help. A similar result was found in another study. So, we’re either barking up the wrong tree, the development of hereditary colon cancer is somehow different than regular colon cancer, or you simply can’t emulate the effects of naturally occurring dietary fiber in plant-rich diets just by giving people some resistant starch supplements.

For resistant starch to work, it has to get all the way to the end of the colon, which is where most tumors form. But, if the bacteria higher up eat it all, then resistant starch may not be protective. So, we also may have to eat fiber to push it along. Thus, we either eat huge amounts of resistant starch—up near the level consumed in Africa, which is twice as much as were tried in the two cancer trials—or we consume foods rich in both resistant starch and fiber. In other words, “[f]rom a public health perspective, eating more of a variety of food rich in dietary fibre including wholegrains, vegetables, fruits, and pulses [such as chickpeas and lentils] is a preferable strategy for reducing cancer risk.”

What’s so great about resistant starch? See my video Resistant Starch and Colon Cancer.

I first broached the subject of intact grains in Are Green Smoothies Bad for You?.

Why should we care about what our gut flora eats? See Gut Dysbiosis: Starving Our Microbial Self.

Did I say putrefaction? See Putrefying Protein and “Toxifying” Enzymes.

Berries don’t just help block starch digestion, but sugar digestion as well. See If Fructose Is Bad, What About Fruit?.

The whole attitude that we can just stuff the effects into a pill is a perfect example of reductionism at work. See Reductionism and the Deficiency Mentality and Why is Nutrition So Commercialized? for more on this.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

70 responses to “The Best Source of Resistant Starch

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  1. I had forgotten about the berries part in the process.

    I have been eating blueberries and blackberries regularly, but I still haven’t tried raspberries or strawberries.

    1. For clarification, in this article your are saying Variety is key:
      Eat whole grains intact AND cooked and or ground?
      Eat starch cold and hot?

      September marks 2 years since my husband and I became plant based, no oil, little salt, and little maple syrup or black strap molasses when added sweetness is needed, mostly depending on dates and overripe bananas. Amazing results in health!
      Every morning we eat oat groats, (100% Rolled Oats when in a hurry). Added to that is ground flax meal, chia seeds, raw bran, a pinch of coarse ground black pepper, a pinch of sea salt, cinnamon, pinch of turmeric, ginger, other spices to vary the taste from day to day, handful of walnuts, prunes, one or two types of frozen berries, ripe banana, and dates. Sometimes it has pumpkin, or chopped apples or peaches, etc. It does take several minutes to put all that in there, but once I do, my husband takes over by stirring after the first 15 minutes and turns it off at the end of the second 15 minutes, adds almond milk if needed while I am getting dressed and ready to go for the day. I feel healthier just writing about it! :)

      1. I have hated berries my whole life.

        I got so sick on strawberries, and had such revulsion to blueberries, plus, was freaked out by Willie Wonka and people getting blue tongues as a kid and raspberries and apricots were my particular, “I hate that” foods.

        I have used my ICES PEMF device to stimulate my vagal nerve to reprogram my emotional relationship with pomegranate seeds, blueberries, and blackberries, but that took many, many months.

        I haven’t tried it with strawberries, but raspberries are worse in my taste bud memory.

        I couldn’t even eat strawberries, raspberries or apricots in very sweetened desserts or cakes or covered in whipped cream.

        I will probably do the process about raspberries eventually because they have a specific super power. I found the chart and my pomegranates and wild blueberries and blackberries don’t even come close.

        1. It makes me angry though that nobody has fined the supplement companies millions of dollars for fraud or shut them down.

          Yes, I know that we can try GMP, but I honestly don’t trust any of them and I don’t trust the government because decades have gone by and they haven’t done anything about blatant fraud.

          The greed of those companies, where they could make billions of dollars without committing fraud, but those billions aren’t enough, they also have to not put the product in.

  2. Okay, so beans are still resistant starch?

    I had it as a separate group in my mind.

    Also, if someone finds a list of how well blueberries and blackberries work, I would appreciate it.

    Blackberries have the most antioxidants and I am in a rhythm eating those and wild blueberries and black grapes.

  3. Don’t take ORAC values to the bank. I believe there have been questions as to the validity of the USDA results and that’s why you see different sites pushing different rankings. That said, safe to say that eating a variety of berries is one of the best things one could do for himself.

  4. I mainly eat my berries in smoothies. Mainly raspberries and blueberries since organic frozen blackberries have been unavailable for the last few months. Am I defeating their benefit by blending them?

  5. Throwing a few berries into salads, casseroles, bean dishes, and grains are a great way to improve flavor, nutrition, and assimilation. Most Americans and others in temperate areas can grow many berries very easily.I grow probably 25 varieties. Free high quality organic food.

  6. Once I started hearing about the superiority of minimally processed foods, I stopped eating American “whole grain” breads and returned to the Danish/German Rugbrot of my youth. Rugbrot looks like roof shingles and if you look closely, you can see that it’s basically Rey & wheat grains that have been glued into a loaf of bread. It also passes Dr Greger’s 5:1 carbs to fiber rule-of-thumb.

    While the Danes invariably use butter, meat and fish on their Smørrebrød sandwiches, I use a shmere of tahini or better still humus and replace the meat with sliced cold potatoes along with tomatoes, cukes, pickles, lettuce, stoneground mustard. It must be a smorgasbord for my lower gut yeasty-beasties by the time it makes it down there. Talk about a win-win!

    1. That sounds good. When I’m traveling and can’t eat my home made, whole grain bread, I eat Multi Grain Wasa bread (no vested interest). It’s a flat bread made from whole grains with a very good ingredient list, is cheap, and available at WalMart believe it or not. Will try your toppings next time.

    2. I just served a smorgastarta at a party: bavarian full rye black shingle bread slathered with three fillings: tofu “egg salad”, beet hummous, and a pea-avocado spread. I frosted it with vegan cream cheese and adorned it with capers, radish, cucumbers, nasturium leaves, calendula flowers and pickled redonions. I love that dense thinly sliced bread!

  7. Wouldn’t a table full of potato starch sold from a health food store mixed in a smoothie provide the resistance benefits we need? Dr Hyman mention this in his books.

      1. Blair,

        I do agree with you about WFPB, but I also do know that people who drink a lot of smoothies get a lot of nutrition but have a harder time with the gut microbiome.

        1. I feel like that is a little different situation than people wanting to eat any old thing.

          Juicing, like Gerson, and green smoothies are very popular, particularly in the cancer community.

    1. Then put a cold potato in your smoother instead of packet starch? And sprinkle whole seeds and beans on top or add SR extras to make a smoothie bowl

      1. Beans and lentils, yes, but the potato starch is supposed to be 72% resistant, so you only need one or two spoons full.

        The potato Dr. Greger mentioned only got a little more resistant after cooking and cooling.

        I am saying it because there are people, for instance, who have been told to only eat pureed food. They certainly can puree a potato and make a vegan cheese with it, but if they are doing green smoothies, they might want raspberries or something easy to add, like the potato starch.

  8. Question: For substitute, how great are plantains and green bananas when it comes to resistant starch because in some areas, berries are not common and they are difficult to preserve?

    1. I looked it up and they were talking about banana starch being very resistant to in vivo amylase hydrolysis. They said that 84% of the starch ingested reached the terminal ileum.

  9. So maybe it’s best not to grind chia and flax seeds. I could never understand how one could not get the nutrients from these whole seeds, unless they were ground, but nonetheless received 100% of the calories from the unground seeds.

  10. Can Beans make us happy? Many years ago I had a copy of “The Miracle of Seratonin”. claiming that there are serotonin receptors in the tummy. Good Medicine just published the work of Leigh Frame, PhD, MhS who is presenting work on the benefits of the microbiome. Bowel disease, prediabetes and premature birth and the microbiome are the subject of her upcoming presentation. When asked what she finds surprising about the microbiome, she says … seems really surprising that neurotransmitters (chemical messengers for the brain are produced in the gut and that the gut microbiome can affect the brain and mental health……”

    Can the stomach have neurotransmitters? No wonder when my friend and I ate a fresh organic pumpkin squash we were happy. Wholistic medicine seems is here!

  11. Are resistant starches the same thing as “prebiotics”. I mix acacia fiber in water…..has anyone heard of acacia fiber as a resistant starch? Thanks!

    1. Hi Barbara – Thanks for your question! Resistant starches do serve as prebiotics. Since resistant starches are not digested in the small intestine, they travel to the large intestine where they begin to ferment and act as a prebiotic that feeds good bacteria.

      I have heard of acacia powder but if you’re looking to try adding more whole food resistant starch food sources to your daily meals, try these: green bananas, legumes (beans, peas, lentils), whole grains, overnight uncooked oats, cooked then cooled rice/potatoes/pasta.

      I hope this helps!
      -Janelle RD (Registered Dietitian & Health Support Volunteer)

  12. Would potato starch be beneficial for a colon cancer patient on chemo with debilitating diarrhea whose physician has told her to minimize fiber?

    1. Arpeggio, that is a brilliant question! I would like to see you get a response from someone in the science field. I have potato starch here and was adding it in smaller starting doses. ( my thinking was to increase the dose as long as my gut responds positively).

    2. Hi, Arpeggio! Generally, colon cancer patients are told to limit high fiber whole grains because they have ostomy, and these foods increase output. When my oldest child was little, and had a bout with diarrhea, I was advised to give her a mixture of pureed apple and banana, and the combined pectins in these two fruits did the trick. I am not sure whether or not this approach could work for you, but it might be worth a try. I would not suggest consuming just potato starch by itself, but try eating cooked and cooled potatoes to see if that makes a difference. I hope that helps!

      1. I had colon cancer 4 years ago after many years of ulcerative colitis, and now have a permanent ileostomy following a total colectomy. Several fellow ostomates I know have been told to avoid high fibre foods but my colorectal surgeon said that once I’d healed up I should be able to eat more or less everything, and this has proved to be the case. The only thing I avoid is sweetcorn because it goes through you like bullets and I’m worried about it causing an obstruction. I am in the process of transitioning to a whole-food plant-based diet and so far so good – I have noticed an increase in output but that’s fine. The only time I’ve been on a low residue diet (low fibre) is for the first 6 weeks after surgery. I have a recurrent parastomal hernia which has been repaired twice and is probably going to need further surgery – I am awaiting results of recent CT scan for the way forward. I am hoping not to have to go low-residue after that because I am really enjoying the whole-food plant-based diet!

  13. I followed the Fast Tract diet book for a few months because I was dealing with GERD. In it, the author suggests that resistant starch is actually the reason for SIBO because good bacteria can’t break down the resistant starch and it ferments via the “bad bacteria”, thus producing gas and pressure with refluxes back up into our stomach and esophagus. My search for relief from GERD eventually lead me to a plant-based diet and thankfully Dr. Greger, but this latest post seems to be 180 degrees from the Fast Tract plan which did bring relief.

    1. Daryl,

      My brother had GERD (among several other conditions) and was taking PPIs for it. But when he switched to plant based eating (and ultimately whole foods) and exercising, it went away and he went off his meds. He also lost about 70 lbs, which probably helped.

    2. I read some of the writings of the person who promotes Fast Tract diet book and he acknowledged that there are studies where resistant starch has improved GI symptoms.

      The thing you have to understand is that there are often different mechanisms at work.

      For instance, people with leaky gut temporarily can’t eat some things, until they heal their leaky gut. People who wiped out their good gut microbiome with antibiotics or RoundUp from not eating organic, often have to do a slow process of healing the gut microbiome through very slow introduction of foods.

      As far as the question of whether Resistant Starch causes SIBO, that source, behind that book acknowledges that some people are also claiming that it helps cure SIBO by healing the gut microbiome.

      I used to not be able to digest onions or garlic or cucumbers and now I have no problem with them and I mean I went from a serious problem where even though I loved them, I could not eat them and it was so uncomfortable that I got rid of them, but after 6 months on Whole Food Plant-Based, they became part of my daily diet. I can eat raw onions now.

      Usually, the people who claim that carbs or resistant starch cause SIBO are from the low carb community and they also believe things like you can’t eat carbs if you have DIabetes.

      I have watched videos on YouTube where Whole Food Plant-Based doctors have told processes of how to very slowly introduce foods until the gut microbiome is healed.

        1. I’m not sure how THAT works. I used to have severe GERD, almost to the point where I would just skip eating and go with water. As you can imagine, that is a recipe for malnutrition. Then I discovered the ketogenic diet, adopted it entirely and got rid of not only the GERD but ALL of my health/medical issues… and I lost over 80 pounds in the first year of the diet without ever going hungry. I’m at my ideal weight now and after several years, I’m still on the ketogenic diet. As you know, the ketogenic diet requires that you stay under 50 grams of carbs a day. My average daily is between 20-30 grams. I love the food on this diet and luckily, I DON’T like the foods that are taboo.

          1. Peter, are pickled peppers allowed?

            Sorry, can’t resist a word or line just made for this kind of retort.

            But seriously, I’ve done a form of keto myself (no doctor supervision and no strict adherence to a set of principles.

            I stopped it when I did a couple of transfusion procedures (7 units of young persons’ plasma and a year later, 2cc of cord blood stem cells.)

            I haven’t started back due to the constant harping here about the dangers of fats on blood vessels. Supposedly keto burns fat so I’m not sure that applies, but I think I’m doing o.k. without keto so am suspending that diet for the time being (My primary oils for doing keto was MCT oil and Walnut oil.)

            I do wonder, and would like to know if anyone is aware of such research, if keto isn’t better used by someone middle aged or younger. I’m not aware of any research done with older folk.

  14. To what temperature should the starches be cooled and the time period that they should be stored to maximize the percent of resistant starch before eaten?

    I guess I should make my oatmeal the day before I eat it and not reheat my sweet potatoes. Also not heat up the cans of beans that I use.

    1. Making things the day before is fabulous.

      You can even reheat things again and may even get higher levels.

      Making big batches and freezing the leftovers works, too.

      I think freezing worked even better, but I read that over 2 years ago so I can’t guarantee that part.

      1. I was just reading that reheating resistant starch makes retrograded starch which is even less digestible than resistant starch.

  15. Just quickly went through the comments and though there were a couple of mentions of bananas… no one made reference to GREEN bananas.

    My readings have listed green bananas as resistant starch and ripe bananas still beneficial, but not as a resistant starch.

    Personally, I buy a bunch of 7 completely green bananas (my local HEB puts them out Tuesday mornings) and I eat one a day. The last couple of ones are speckled and ripe but for a few days I get the resistant starch I need.

    1. Just did a more detailed read of the posts above and noticed that Sammy did reference green bananas as a resistant starch… and plantains too. ‘-)

  16. How do people with GI issues – like gastroparesis – and those who cannot digest the bulk/ fiber associated with these foods (i.e. intact grains) reap the benefits you describe? It sounds like making a raspberry smoothie wouldn’t be the same as eating a bowlful of the whole fruit, either. Speaking of smoothies, could you share or do a video on what an ideal powerhouse nutrition smoothie would look like/ contain?

    1. P, you can plunk in a topic in the search bar to come up with videos and articles on just about everything to do with nutrition. Here is what Dr G has to say about smoothies

      I have gastroparesis, but once I got rid of the dairy products and other animal products, I did not have a problem. I probably get over 75 grams fiber per day. The water content of the fresh foods helps me anyway. I eat oat porridge in the morning with berries and a splash of soy milk and no problems.

      1. i have Gastroparesis, been on a plant based, mostly whole food for years.Beans and starches are still the hardest to digest.They can sit in the stomach for hours . Beans tend to digest better when pureed.

        1. Beans tend to digest better when pureed.
          My regional chain has a store brand of refried beans that are fat free. They come in a can with no apparent plastic stuff so I trust the product.

          I’ll often open a can of this and add some glass jar Ro-tel Diced tomatos and green chilis… and sometimes some Herdez guacamole sauce.

          This can stand in for a complete meal or two.

          1. I think all cans are lined with plastic even if it is not evident. Isn’t this correct? That’s why I drive 70 miles once a year to stock up on organic tomato products in glass jars.

            1. I think all cans are lined with plastic even if it is not evident. Isn’t this correct?
              No, and while I’m not 100% positive on the refried beans cans (I haven’t examined them closely but I will the next time I open a can)… I am sure about some cans. For instance, some canned pears I opened just recently. Really there’s no reason to plasticize the inside of the bean can since they are not acidic so the food should have no reaction with the metal.
              That’s why I drive 70 miles once a year to stock up on organic tomato products in glass jars.
              I like this solution. ‘-)

            2. Yep… it’s always a good idea to get tomatoes in glass, due to the acidity in the tomatoes, which can even RUST the can if the “best by” date has gone long enough over the expiration. As far as canned foods, I always make sure I buy the Eden brand. They guarantee no BPA, no BPS, and no plastic. There may be other brands out there that do the same but Eden is the only one I am aware of to date.

    2. Hi P! I will echo what Barb said. Gastroparesis may be caused by diabetes or nerve damage. If it is caused by diabetes, then a whole food, plant-based diet is likely to help. If you are unable to digest intact whole grains, try slightly more processed forms until you find what will work for you. For example, intact whole oat groats are longest to cook and hardest to digest. Steel cut oats are slightly more processed, quicker cooking, and easier to digest. Rolled oats are slightly more processed than that, much quicker cooking, and easier to digest. Oat flour is even more processed and easier to digest. As Barb pointed out, you can find everything on this site related to smoothies here:
      This may be of particular interest:
      I hope that helps!

  17. All good, I agree. However you may want to change your date of ” resistant starch” . No, it was not called by that term at that time but does the same thing.
    Check into Dr Moro’s Soup…twice cooked carrots to produce those short 3 carbon
    chain carbs that grow the “right” colon bacteria. And cooked carrots are a vegetable that most people will not reject. An easy way to “cleanse” the digestive system of previous animal food bacteria growth…just daily add lots of twice cooked, long cooked carrots to your menu of every meal.

  18. I have a question. I have an ileostomy d/t ulcerative colitis. My GI doc has prescribed fatty acid chain enemas for diversion colitis. Are there any other options I can use?

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