Is Starch Good or Bad for You? You Be the Judge. | Chris Kresser

Is Starch a Beneficial Nutrient or a Toxin? You Be the Judge.

by Chris Kresser

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sweet potatoes
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As many of you know, I’m currently at the Ancestral Health Symposium at Harvard University. Yesterday I participated on a panel organized and moderated by Jimmy Moore called “Safe Starches: Are They Essential on an Ancestral Diet?” The panelists were myself and Paul Jaminet on the “pro-starch” side, and Dr. Ron Rosedale and Dr. Cate Shanahan on the “anti-starch” side (though Cate’s position is not quite as cut-and-dry as Ron’s).

I’m giving my talk on iron overload today, so I don’t have a lot of time, but I wanted to at least summarize the “anti-starch” side’s arguments and then list some bullet points of my arguments in favor of starch for those of you who aren’t here. I’m not sure if the panels will be made available after the fact (the talks will be).

Ron and Cate believe that glucose is toxic in any concentration, and it’s just a matter of scale. In fact, Ron is fond of saying that “everyone is diabetic”. Since starch breaks down into glucose, then by definition starch is toxic and should be avoided – by everyone. I’m a little less clear on Cate’s position, but she seemed to argue that glucose raises insulin, and insulin causes problems, so everyone should be on a low-carb diet ranging from 20 – 70 grams of carbohydrate a day, starch included.

My arguments in favor of starch

  • Let’s define the terms: are we debating whether starch is “safe” in healthy people or people with particular health conditions like diabetes or small-intestine bacterial overgrowth? These are very different conversations. People with hereditary hemochromatosis (a disorder that causes iron overload) should not eat iron-rich foods like liver and mussels; does that mean everyone should avoid these foods? Even if starch/glucose is “toxic” for diabetics, should everyone avoid starch/glucose?
  • If the argument is that starch is not safe for healthy people, I would say there’s little to no scientific or anthropological evidence to support that idea, and overwhelming evidence opposing it.
  • There are literally billions of people eating high-starch diets worldwide, and you can find many examples of cultures that consume a large percentage of calories from starch where obesity, metabolic problems and modern, inflammatory disease are rare or nonexistent. These include the Kitava in the Pacific Islands, Tukisenta in the Papa New Guinea Highlands and Okinawans in Japan among others. The Kitavan diet is 69% carb, 21% fat, and 10% protein. The Okinawan diet is even more carb-heavy, at 85% carb, 9% protein and 6% fat. The Tukisenta diet is astonishingly high in carbohydrate: 94.6% according to extensive studies in the 60s and 70s. All of these cultures are fit and lean with low and practically non-existent rates of heart disease and other modern chronic disease.
  • Amylase is thought to have played a key role in human evolution in allowing humans an alternative to fruit and protein. Compared with primates, humans have many more copies of a gene (AMY1) essential for breaking down calorie-rich starches. The ability to digest starch, along with the discovery of fire and cooking, gave humans a new food source that allowed us to thrive even in marginal environments. Some scientists have even argued that consumption of starch, along with meat, was primarily responsible for the increase in our brain size.
  • Dr. Rosedale argues that evolution is optimized for fertility, not longevity, and that starch consumption decreases longevity. The evidence he cites from this come from studies of roundworm, C. Elegans. However, I am not aware of any evidence in humans showing that starch consumption decreases longevity, and some of the longest lived cultures in the world consume large amounts of starch. Okinawans over the age of 65 (who grew up eating a traditional diet) are a prime example. According to a study of the traditional Okinawan diet in 1949, they obtained 85% of calories from starch, mostly from sweet potato. Life expectancy was 86 years for women and 77.6 years for men. Life expectancy at age 65 is the highest in the world, at 24.1 years for females and 18.5 years for males. Finally, the Okinawan population has the highest prevalence of centenarians in the world. This is especially remarkable when you consider that Okinawans did not have access to modern medical care during the 40s & 50s and and higher rates of death due to infections like tuberculosis as a result. If glucose is toxic and promotes short lifespan, how do the Okinawans live so long?
  • There is no one-size-fits-all approach. The amount of starch (and carbohydrate in general) will depend upon genetic/epigenetic factors (like amylase production), existing health conditions and the volume and intensity of activity – among others.
  • If the argument is that starch isn’t safe for those with impaired glucose tolerance, I concede that may be true in many cases. However, I’d like to point out that there’s some evidence that suggests starch may be safe in this population as well. For example, low-fat diets also cause fat loss (even without deliberate calorie restriction), though to a lesser extent than low-carb diets. And there are documented cases of people losing significant amounts of weight and improving metabolic parameters by eating nothing but potatoes. For example, Chris Voigt lost 21 pounds over the course of two months by eating only potatoes and not deliberately restricting calories. Furthermore, his fasting glucose decreased by 10 mg/dL (104 to 94 mg/dL), his serum triglycerides dropped by nearly 50%, his HDL cholesterol increased slightly, and his calculated LDL cholesterol dropped by a stunning 41% (142 to 84 mg/dL).

There’s more, but I don’t think it’s necessary to go further. If Drs. Rosedale and Shanahan are going to advise us to avoid an entire class of food that has been eaten for a couple of million years by humans, the burden of proof is on them to tell us why that food isn’t safe. Evidence from roundworm experiments and biochemical/mechanistic speculation is not enough in the face of overwhelming evidence that starch and glucose are safe in the absence of certain existing health conditions.

Now I’d like to hear from you. Which side of this debate are you on?

355 Comments

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  1. Hi, i think i may have a potential solution for starch indigestion using potato fermentation which might work. i have celiac and also dont eat other grains like rice and corn (paleo-ish). i noticed that i had trouble digesting high starch foods even after months of being gluten free, 2-3 years back after my celiac diagnosis. Any time i ate boiled/baked potatoes, sweet potato, beets or sago(similar to tapioca) i got instant stomach pain, diarrhoea and gas. i could only tolerate limited amounts(2-3) of potato fries if i specifically fried them at low heat and only at high heat at the end once they were mostly cooked, that probably somehow changed the starch structure specially the inside of the fries and i didnt get the digestive symptoms.

    Anyways i thought the reason for all our symtpoms could be the absence of bacteria that digest or handle starch in our intestines. i tried to research on it but couldnt find any references to people fixing starch indigestion with fermented foods or probiotics nor much info related to sources of bacteria with CAZYmes for starch digestion in humans. So i thought maybe i could culture bacteria that were good at starch digestion and eat those, that got me the idea of fermenting potatoes. Then i tried searching for recipes for fermenting potatoes, and there werent many on the internet and most people used a starter but i wanted wild fermentation since i probably had the bacteria the starter had, and people used to cook the potatoes after fermentation which would have killed the bacteria. i also remembered reading somewhere that potatoes were buried in the soil dug near rivers for months by a tribe or something and were considered a cure for a lot of stuff. Maybe tim steele posted it in comments somewhere (couldnt find it again, if someone knows about it let me know).
    Anyways i improvised and heres the recipe.
    1) Peal and cut 3-5 potatoes in the shape of fries.
    2) Separate pieces of almost 1 potato and boil the rest. (The pieces of potatoes that werent boiled should have soil bacteria that would be used as the starter for our wild fermentation)
    3) Once the potatoes that were boiling are soft-ish, take them off the heat, discard the water, maybe rinse the potatoes once or twice and let them cool to room temperature.
    4) Add the unboiled and boiled potatoes to your fermentation vessel (i used air tight glass food storage contatiner), add water until potatoes are 1 inch below water level, add 2-3 tablespoon salt, Mix and put on the air tight cover. There should be 1 inch space between cover and water level also.
    5) Store in a cupboard or in a warm place for 2 days or longer if its winter.

    The potatoes and brine should taste sour and probably smell after fermentation. The reason that i boiled the potatoes was that so that they become more digestible and starch was closer to what we normally eat instead of high resistant starch. Dosage was about 2-3 tablespoon per day, with food.

    Within a few days i had less trouble digesting starch and after a week or more i could eat high quanties of boiled potatoes, other starchy vegetables and sago without any digestive symptoms, normal stools and no stomach pain.
    i know this seems like a miracle cure and i was surprised too but since there is already so much info on how gut bacteria affect our body and digestion, this isnt too crazy. This might not even work for others but maybe it helps someone and that would be good enough. And my reasoning for various things could be flawed of course since im just throwing out ideas and experimenting in the wild. Maybe someone could find the reason behind this under laboratory conditions.

    Remember that changing your gut bacteria population could be dangerous specially for the ibs people. Experiment at your own risk. And if you do, let me know of your results whatever they may be.
    Also note any changes to your immunity, digestion of other foods like fruits, and mouth odor after taking this for a week or so and let me know.

    Also another thing is that joint points probably due to nightshade/potato are still there but a bit lesser. i noticed that if i boil the potatoes and discard the water and rinse them and then eat them i barely get the joint points. That probably reduces the levels of toxins. Maybe the new gut bacteria also break down some of the toxins. Also you could try cooking fermented potatoes, those might have low amounts of toxins too.

  2. I think a key point is not just the percentage or carbohydrate being consumed but the quantity in order to complete the equation. For example I could eat a diet with a high percentage of carbohydrates and remain metabolically healthy if there are not simple carbohydrates that are rapidly digestible and I am not eating a high volume. My guess is that those eating a high percentage of carbohydrates are not eating a high calorie diet and that a good portion of those carbohydrates are likely fiber, which also aids in buffering digestion so slows the uptake of glucose to keep insulin levels low.

  3. Sorry for the delayed response, this email isn’t my active one.

    A good measure is watching your stools over a few days. If you start to have a lot of gas, smelly stools/farts then you know you ate too few Creon to digest the food.

    We live in an amazing time where we have such medication available to us. If I wasn’t alive in this time period I may not have made it far past 17. A decade has passed and I’m managing my current condition well.

    The internet is a great source of information but unfortunately misinformation is rampant. It can be difficult separating fact from fiction.

    Basic guideline to longevity and health – follow a balanced diet, make sure you’re in the healthy weight category and adjust calories accordingly.

    All the best 🙂

    • your p1ss poor advice is giving the thumbs up to medications. And that right there is a big no no. Just eating your way through life and when you don’t feel well, not linking to your diet, but adding some pills for this, pills for that. Real smart. Its your life, but keep in mind you are supporting the largest most fraudulent industry in recent times – called healthcare.

    • What does “a balanced diet” mean? It means different things for different people. If you are metabolically healthy and ‘normal’ weight then that tells you that you are eating a balanced diet that is right for you, whereas someone else eating that same diet may not be metabolically healthy and be at a ‘normal’ weight.

  4. I seem to have a starch intolerance. Its taken me a year to figure it out through eliminating diet, but as soon as I eat potato, rice, grains, red kidney beans, as well as thickeners like agar agar or tapioca, chestnuts, or figs, or any by products (corn starch, rice flour) I get terrible mucus for a week, really itchy mouth, tiredness, increased heat rate and redness. I’m absolutely fine with sweet potatoes, dates, prunes, root vegetables, pumpkin and bananas, so it’s not all starch! And I can’t figure out what the difference is between the first foods and the second… (if anyone knows please tell me!) I miss the ease of being about to eat bread, potatoes and rice, having to look at every single ingredient, but I’m 100% healthier when I avoid them. Really it’s night and day. Wish I knew the answer why this suddenly started, and how I can get back to eating them without the intolerance side-effects. Would love your thoughts Chris.

    • Rice, beans, and potatoes are all starch. Starch is a binder. It is a chemical. To tie two unequal chemicals you have to use a starch. That’s how some of these hybrid foods are created. People become sick from eating “starch and blood.”

      “Starch is not a food, starch is a chemical. Anything that god made has no starch.” – Dr Sebi

  5. My doctor put me on Creon and I feel like I’m being poisoned I feel so sick. Says I have pancreatitis. Starch is the easiest thing for me to digest so I eat a lot of white rice which may be hurting my pancreas. I don’t know what to do. Just trying to eat a lot of cooked vegetables because raw gives me a stomach ache. Creon is digestive enzymes from pigs. The vegetable enzymes in pill form give me terrible bloating and pain. Help!

    • Hey Judy,

      I’ve had pancreatitis for almost a decade, diagnosed at age 17.

      Creon has been imperative in absorbing the food I consume, maintaining a healthy body weight and eliminating the symptoms of steatorrhea (fats in stool).

      I feel the medication is completely safe. It’s just digestive enzymes, your body will use what it needs and the rest will be excreted. I’ve have had no noticeable side effects for the past 10 years of using the medication.

      Personally I follow a high protein, moderate carb and low fat diet. No real dietary restrictions. I adjust the dosing of Creon depending on what I’m eating. Rough estimate is 1 capsule of Creon 10,000 per 5 grams of fat.

      All the best!

      • Dear Anon, Thanks so much for your reply which I just saw. It helps a lot as I was only eating 10 grams of fat a day but my doctor had me on 9 creons a day at 24,000 each. I am now taking 1 a day and staying at 10 grams of fat and feel fine.

        • Sorry for the delayed response, this email isn’t my active one.

          A good measure is watching your stools over a few days. If you start to have a lot of gas, smelly stools/farts then you know you ate too few Creon to digest the food.

          We live in an amazing time where we have such medication available to us. If I wasn’t alive in this time period I may not have made it far past 17. A decade has passed and I’m managing my current condition well.

          The internet is a great source of information but unfortunately misinformation is rampant. It can be difficult separating fact from fiction.

          Basic guideline to longevity and health – follow a balanced diet, make sure you’re in the healthy weight category and adjust calories accordingly.

          All the best ?

  6. i started a starch starvation diet from two weeks ago , loss weight is unprecedented for me given that i tried many diets before but no vain , however i feel lack of power considerably .
    i substitute all with mainly proteins and low glucose alternatives .

  7. Late to join, I know, but I wanted to add this.
    The brain and muscles run on glucose. You will die without it. But glucose is toxic?
    Cortisol is essential for proper metabolism but all mainstream media focuses on is it’s relation to stress. Is it toxic? Above a certain threshold it is toxic, but it is ever present in our blood stream and is essential to life. Without it, you will die.

    I’m only 16, but I’ve nearly completed my BS in bioengineering. My younger sister and I live on a high starch diet: I do all the cooking for us. I run between 3 and 5 miles a day, and between 15 and 20 on Saturday or Sunday. She’s 10, and a couch potato, spending most of her day programming or studying star charts. Both of us are in optimal health. I lived in Saitama for years, and I’ve hut-hopped through the Philippines. I’ve seen the same quality of health from those cultures as I do in my home. The notion that high-starch diets are detrimental to health, especially longevity, when all of the centenarians consume high-starch diets is simply untenable. The problem with the glucose naysayers is that they are misinterpreting their data or taking it out of context, sometimes both.
    I’ve studied the genes of a couple centenarians and several people deceased and alive who are profoundly obese and have easily concluded the problem with the latter’s diet was not the presence of starch, but the absence of it and the over-abundance of animal protein fragments and synthetic fatty acids. There is nothing specifically genetic that makes a centenarian’s life span possible.

    • You write so elaborately well. Go tell the billions of Asians that have been living on high starch diets (rice) for thousands of years that starch is not healthy!

    • Zoe S,

      If you’re really “only 16” and have “nearly completed” a “BS” in Bioengineering, I would be inclined to be believe that “BS” has more to do with manure than with any university degree of any kind that has to do with engineering of any sort, whether bio or otherwise.
      You really ought to keep the BS where it belongs…
      Cheers
      KM

    • The brain and muscles are more efficient on ketones. the brain requires about 15% glucose. Glucose is produced by the body by gluconeogenesis so carbohydrates are not a necessary nutrient.

      You have a very young and robust metabolism as well as healthy organs that hopefully will not been exposed to excessive processed carbohydrates, which is the primary cause of today’s obesity epidemic.

      Unfortunately much of the rice harvested today is not like that of even 40 years ago and is causing massive problems with obesity in Asia now due to it being so rapidly digestible and converted to glucose.

  8. Timothy, Matt, Robin H, robin dixon and who ever, I did the Genova testing along with Diagnostechs and results show I do not have leaky gut, sibo, ibs, or low stomach acid etc. Turns out my initial self diagnosis of parasites years ago was correct… both tests picked up on a severe infection of Blastocystis Hominis and minor inflammation of the colon. Apparently a common parasite, but one of the hardest to remove. Partly explains why Humaworm years ago did nilch. I’m taking herbs over the next 4-5 months for it now, alternating them like you should (unlike Humaworm), so hopefully that makes a difference. Yet I read online many find no luck this route. There are antibiotics that work better, but are not available in Canada.

    For anyone considering doing GI testing, take into consideration that Diagnostechs picked up on internal bleeding that Genova did not. And Genova picked up on a Butyrate deficiency which Diagnostechs could not. Both issues which are indicators or prerequisites for colon cancer. I went with two companies for this reason, as others on the web had mentioned the same inconsistency with testing. And it has been especially valuable for me because low Butyrate could have led to the parasites, as low Butyrate means your immune system is weak, which makes your GI vulnerable to parasitic infection. On the other hand, parasites could be the cause of low Butyrate, because my immune system is so taxed dealing with the parasites. A question of which came first… So I am addressing the Butyrate issue as well, with Calcium D Glucarate, as prescribed. And I could not have addressed this issue without having done Genova. And if I don’t solve my low Butyrate deficiency, the parasites could return after removal. Should mention, Genova also picked up on low enzyme production which Genova didn’t.

    On the upside, my Naturopath does not think I have Psoriasis, but Hypertrophic Keratosis. I have yet to get a second opinion on this and will post when I do. I question her diagnosis as she said it’s caused by a vitamin A deficiency, but I read myself that it’s caused by too much sun exposure (which is impossible as I’m an obligatory hermit), so that all makes me question her.

    Will keep everyone posted on the outcome. Be back in a few months when the herbs are gone. Guess if they don’t work the next course of actions is smuggling antibiotics in…

    • Forgot to mention that Genova shows I’m severely depleted of Bifidobacterium, usually one of the most numerous and thus most important bacteria’s in the gut. Also low on some other strains, all of which Diagnostechs does not test for. So I will be supplementing with Pro-15 despite the fact that the high histamine content of probiotic’s makes me want to die. So once again, good things come from testing with multiple companies x_x

      • I’ve had similar diagnosis -B.Hominis ( apparently hominid misnomer as there is not a human only form!) I don’t appear to have symptoms ( but may have inflammation related that has not been connected e.g. no explanation for psoriasis) .. Anyway so I’ve not taken it seriously i.e. to take the bitter herbs.. the 2 mths antibiotic – Flagyl changed nothing but made me more reactive than normal to chemicals..And probably disturbed whole gut in process. Have taken Probiotic supplements for 6 mths at increasing doses and still made no dent on the low Bifido levels. So gave up the drug/supplement approach.
        Butyrate is the med chain fat present in coconut oil and a liquid hi potency cooking oil is avail. in supermarket (in Australia) and its also in butter and ghee. Butyrate is also produced by the bacteria that should be in the colon feeding off undigestible (resistant) starches – The Bifido ones. So my deduction is: a) not enough of these foods(s) or overall bacteria levels too low or ratio of “good/bad” is imbalanced. So chicken & egg. But in ecology systems it is habitat that determine population / extinction. So my guess is insufficient fibre in diet is setting stage allowing for increased non-beneficial over beneficial colon bacteria. The non -beneficial like BH are adept at feeding off poorly digested foodstuffs so there is also an indicator for problems higher up the gut. Gluten seems to be the serious culprit for gut disturbances and needs priority to address IMO. Like you, I also seem to have histamine issues and have reacted it seems to increases in live / cultured foods- e.g. kombucha, ACV, sauerkraut.. so I am not sure that cont. probiotics is a good idea -if you are reacting severely… esp w/o feeding them resistant starch foods ( rather than fibre supplements). I believe the low levels are indicating high order issues that need priority to address – Gluten sensitivity, dairy and sugar. So am starting on total avoidance several months before retesting stool again

    • So the controversy still rages as shown in many replies. One thing to consider regarding the Okinawans is that the prevalence of the e2/e3 APOE genetic variant in Japan is only about 3%, while it is more like 12% in the West among Caucasians, even a bit higher among African Americans. This variant is associated with exaggerated response to carbs, especially starchy ones. It is a mistake to take sides too confidently. To more or less quote Barry Sears, people are unreasonably stubborn about 3 things: religion, politics and diet.

  9. You said, low fat causes weight loss. This could not be further from the truth.

    Low fat diets cause Weight Gain.

    High fat diets cause Weight Loss.

    You should eat as much fat as possible, butter, healthy oils like olive and coconut oil, tons of high fat meats, especially red meat and high fat bacon.

    Just avoid anything with high fructose corn syrup, artificial sweeteners, preservatives, and other chemical poisons.

    Also, decrease your portion sizes.

    • When you let go of your “self-righteous” thought process you might consider that every human being has a natural biological composition. Not all humans operate or thrive on the same diet.

    • “Low fat diets cause Weight Gain”? Well I’ve had a fairly low-fat diet for roughly the past two decades (since my teens), where I hardly eat greasy foods, desserts, and fatty dairy products. On top of which, I have mainly a non-athletic lifestyle, yet I’ve had practically the same weight through the decades. Where was the weight gain you mentioned?

    • “You should eat as much fat as possible,” this comment needs to be moderated.
      Stuff yourself with it and deprive self of other nutrients? Does type of fat matter ?

      Fat needs to be free of processing chemicals and heat treatments…. it cannot be in consumed in (misleadingly large volumes as this overdoes calories and prevents appetite for low calorie much need needed vegetable -plant carbs. These are needed for antioxidants etc too. (And results in constipation and bowel bacteria starvation..)
      True… LF Diet CAN cause weight gain esp if already overweight as hunger hormone is malfunctioning. And… Low fat diet may take years to show up problems..
      LF Diet seems to need to be have strict “clean” diet of massive amount of plant matter to supply calories protein and omega fats. So that needs to be considered. Including excess seeds /grains in such may induce deficiencies states as they’ve got anti-nutrients that inhibit mineral absorption- esp. in genetically susceptible people. In normal digestion fat is limited hormonally so long as the fat itself is not excessively processed or contaminated by the agricultural practices, so LF seems to be directed towards those whose diet has been using hi processed fats and oils which the liver cannot detoxify and essentially causes inflammatory conditions in the body. Using “clean” fats assists digestion and health…

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