Resistant Starch and Fiber

Carbohydrates get a bad rap. For most of them it is well-deserved. Sugars and starches that are digested rapidly, commonly classified as those with high glycemic index (GI), are very harmful to maintaining stable blood glucose. They cause a burst of insulin release in a rush to reduce the very damaging high levels of glucose circulating in the blood. This creates more metabolic damage. Immediately, it encourages the body to store more fat because the elevated insulin turns off fat burning and turns on fat storage. Longer term, it triggers insulin resistance and leptin resistance that are major hormonal factors in chronic poor health.

However, not all carbohydrates are problematic in these ways. Fiber and resistant starch are two types that appear to be highly beneficial to gut function. Unfortunately, the common insoluble fiber supplements that might come to mind are not likely to be all that helpful. Those appear to function as little more than a mechanical broom or abrasive brush rather than as a source of food for gut bacteria. Instead, it is the soluble fiber and resistant starch that acts as a bacterial food source to feed the many microbes in the intestines.

Soluble fiber and resistant starch help feed beneficial microbes and they in turn help prevent pathogens from proliferating excessively. In the process, they make useful nutrients for the human host. Among these are butyrate, a short-chain fatty acid that is essential to the health of the large intestine and which also is reputed to reduce appetite, thereby assisting with weight loss and maintenance goals. Proprionate and acetate are two more short-chain fatty acids that can be made in the large intestine by fermenting fiber and resistant starch. Common foods that include these short chain fatty acids are butter containing butyrate and vinegar containing acetate.

A possible problem with very low carbohydrate and ketogenic diets may be that they deprive health gut bacteria of a food source. This can cause their populations to collapse, enabling overgrowth or infection with pathogenic organisms such as Clostridium difficile and candida albicans. Even if pathogens don’t grow out of control, the lack of short chain fatty acids alone can cause health problems. Butyrate is particularly important in the large intestine where it provides essential nutrition for the human cells lining the organ. Low levels of butyrate are regarded as a risk factor for various colon diseases including colon cancer.

However, some caution that resistant starch could also provide a fermentable food source for bacteria that have overgrown the small intestine. This could worsen symptoms of SIBO (Small Intestinal Bacterial Overgrowth) or IBS (Irritable Bowel Syndrome), for instance by increasing the level of uncomfortable gas and bloating. Yet some people with these problems have noted that unmodified potato starch (a source of Resistant Starch type 2) has helped them with these conditions. It is thought that the resistant starch may induce bacteria to latch on and grab a ride out of the body. Along this lines of thinking, resistant starch is being used as a treatment for diarrhea due to cholera.

Probiotics are also commonly recommended for use with resistant starch and fiber. Some caution is warranted when combining these because you can inadvertently create a condition that looks a lot like SIBO if you combine a rapidly digested bacterial food source along with a probiotic that can eat it and take both at about the same time. This can cause the fermentation to start in the stomach and small intestine, leading in some cases to the same kinds of symptoms you would see with SIBO, particularly the painful gas and bloating.

Diarrhea can also be triggered when the small intestinal cells see unusual bacterial activity and speed up the transit so that digestion is incomplete. The bacteria themselves could be sending biochemical messages to the intestinal cells to make them speed along the intestinal contents. One of the ways this could happen is that serotonin levels can increase in the gut. Serotonin is usually discussed in the context of the brain and its effects on mood, but it has important roles elsewhere in the body including acting as an enteric (gut) neurotransmitter used to cause enteric nervous system cells to modulate muscle movement to propel the contents of the small intestines forward. Much of the serotonin in the human body is made by certain bacteria in the human gut. Some estimates peg the bacterial produced serotonin at around 95% of the serotonin in the human body.

Increased levels of serotonin are why drugs and supplements that affect serotonin, such as SSRI anti-depressants and tryptophan and 5HTP, sometimes can trigger diarrhea just by themselves. High levels of serotonin producing bacteria and a food source they can rapidly digest is also likely to be able to worsen or even trigger diarrhea.

Part of the strategy of consuming resistant starch and fiber along with probiotics is to watch for adverse effects and alter the combinations and timing to avoid them. For instance, if you get SIBO or IBS symptoms from combining the two or taking them close together, then try taking the probiotic a couple of hours away from anything it could eat.

Such symptoms could also mean you are missing some kind of cross-feeding microbes needed to consume the fermentation products of the probiotics and prebiotics you are using. That may mean you need to add yet more probiotics that are carefully selected to be able to eat the products of the ones producing the painful gas and bloating.

Given that the gut biota vary from person to person, what happens may be difficult to predict absent some kind of gut biome profile obtained from DNA testing of a fecal sample. Therefore some caution is in order when experimenting with increased intake of resistant starch and fiber. If you start with a small amount, you may be able to more comfortably determine if there is potential for adverse effect rather than just jumping in with large doses and finding gut problems are magnified.

Because the biota may be off in some people, many who are experimenting with resistant starch supplementation report that using certain probiotics such as Prescript-Assist, Primal Defense Ultra, and AOR Probiotic-3 help populate the gut with beneficial species to improve results.

Australia Broadcasting Corporation’s Catalyst science TV program produced some helpful videos that discuss the importance of gut bacteria and short-chain fatty acids to human health.



Gut Reaction Part 1


Gut Reaction Part 2

These are well worth watching. The information overall is of good accuracy except for the suggestions that eating grains and legumes is a good way to get more resistant starch to improve gut and overall health.

Unfortunately, the RS1 (Resistant Starch type 1) present in grains and legumes is in very low percentages and comes along with a high level of lectins (plant defensive proteins) such as gluten and gliadin that are likely to damage the gut lining. Gluten raises the levels of the hormone zonulin. This loosens up the gaps between gut cells, thereby increasing the likelihood of leaking of undigested proteins, toxins, and even pathogens (bacteria, fungi, parasites, etc.) into the bloodstream. Zonulin also loosens up the blood-brain barrier, making whatever nasties got into the blood much more likely to cross into the CSF (cerebrospinal fluid) and into the brain. Zonulin also affects lung membrane functions, and so could be tied to respiratory ailments such as asthma and COPD (Chronic Obstructive Pulmonary Disease).

Wheat also includes compounds called gluteomorphines which resemble morphine, heroin, and other opiates in their addictive pain-numbing effects. When gluten, gliadin, and related lectins get through the gut lining into the blood, they are very prone to migrate to tissues that resemble the biochemical composition of insect guts, exoskeletons, and bacterial and fungal cell walls. They tend to damage organs such as joints, thyroid, and brain and trigger autoimmune reactions in all those tissues as well as others.

Even if your immune system is able to mop up the lectin damage, the gluteomorphines in wheat can create addictive reactions in the brain much like heroin. Beyond the high glycemic load and blood glucose and insulin roller coaster effects of many foods containing wheat, the gluteomorphines can add even more addictive potential. For a much more in-depth exploration of the ravages caused by grains, please consult books such as Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back To Health by cardiologist William Davis, M.D., and Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar–Your Brain’s Silent Killers by neurologist David Perlmutter, M.D.

Although RS1 foods such as grains are very widely consumed, they are among the worst choices for resistant starch and fiber in your diet. If you dare to eat RS1 sources, try to pick safer sources than wheat and its many close relatives such as rye. As an example of a safer RS1 food source, black beans have relatively high amounts of resistant starch compared to other foods containing RS1 and avoid the worst of the wheat-style lectins and gluteomorphines.

Much safer and higher percentage sources of resistant starch are RS2 (Resistant Starch type 2) foods like uncooked, unmodified potato starch and green banana or plaintain flour. Although potatoes are a nightshade and therefore can trigger allergic or autoimmune reactions, the simple mechanical process of extracting the starch is believed to eliminate nearly all of the deleterious nightshade proteins.

Resistant Starch type 3 sources include foods that are cooked and then cooled or frozen to increase the percentage of resistant starch. Potatoes and sushi (short grain sticky) rice are among the better foods here, but you could also eat cold beans or frozen bread. (Yum!) Some experts are now claiming that RS3 resistant starch are a preferred form because they ferment more slowly than RS2 sources and may therefore avoid rapid fermentation in the small intestine that can create painful gas and bloating.

Resistant Starch type 4 sources are synthetically produced by chemical processing. They are often derived from processing corn which is likely to be unhealthy due to how most corn grown is now genetically modified and therefore may carry toxin producing plasmid genes (which could turn your gut bacteria into poison factories), high levels of mycotoxins (mold toxins), and low mineral levels. However, if you can find RS4 made from non-GMO organic corn then this might be an acceptable source.

Tim Steele, one of the folks responsible for collecting and disseminating a lot of information on resistant starch and its effects, has assembled a list of many foods and their approximate levels of resistant starch.

Resistant starch is being discussed as an important means to improve gut health by eliminating SIBO (small intestinal bacterial overgrowth) and pathogenic bacteria and candida infection. See How to eliminate Candida & biofilms for more information.

More Details on Resistant Starch

Resistant Starch – a concise guide to the biohack of the decade

Resistant Starch – Friend or Foe?

A Gut Microbiome, Soil-Based Probiotic, and Resistant Starch Primer For Newbies

The Definitive Guide to Resistant Starch
Resistant Starch: Your Questions Answered

Revisiting Resistant Starch: Part One
Revisiting Resistant Starch: Part Two
Revisiting Resistant Starch: Part Three

My n=1 Pre- and Post-Microbiome, Digestion, SCFA, Fat Malabsorption, Pancreatic Insufficiency, Leanness F:B Ratio, and How I Healed SIBO and the Gut-HPA-Gonad Axis

Is there such a thing as Bulletproof Resistant Starch?

Short-Chain Fatty Acids and Human Colonic Function: Roles of Resistant Starch and Nonstarch Polysaccharides

Colonic health: fermentation and short chain fatty acids

Short chain fatty acids and colonic health

Foods And Supplements High In Resistant Starch

These foods and supplements are high in RS2. Consume them without heating as above about 140 degrees Fahrenheit the RS2 turns into rapidly digested starch.

Tigers Nuts – Premium Organic

Tiger Nuts – Supreme Peeled

Bob’s Red Mill Potato Starch Raw Unmodified

Anthony’s Organic Potato Starch

Nutryvitta Green Banana Flour

WEDO Banana Flour

Barry Farm Plantain Flour

Farming and Gardening Resistant Starch

Chufa (Tiger Nuts) for Wild Turkeys

How Do You Grow Chufa For Ducks?

Chufa (Tiger Nut) seeds for planting

Adverse health affects of grains

Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back To Health

Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar–Your Brain’s Silent Killers

Physiological, Pathological, and Therapeutic Implications of Zonulin-Mediated Intestinal Barrier Modulation

Zonulin – A Novel Player In Human Lung Pathophysiology

Resistant Starch Videos

Dr. Michael Ruscio on Resistant Starch, Low Carb, and Gut Flora

Dr. Michael Ruscio Resistant Starch Updates

General information on gut health

Chris Kresser’s Gut Health E-Book (free)


These statements have not been evaluated by the Food and Drug Administration. The products mentioned in this post and on this website are not intended to diagnose, treat, cure or prevent any disease. The information presented here is for educational purposes and does not constitute medical advice. Please obtain medical advice from qualified healthcare providers. Pursuant to FTC regulations, please be aware some of the links herein may be affiliate iinks. If you click on them and complete a purchase, this website may earn a commission.


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