Fiber & Resistant Starch

Updated: Sep 2

It’s impossible to have healthy digestion without adequate dietary fiber. Fiber comes in a variety of types: soluble, insoluble, fermentable and non-fermentable types of fiber. All fiber is found in plants, so a plant-based diet of 70% is ideal for eating at least 25 grams of fiber daily. Increasing fiber about 5 grams every couple days to prevent GI distress is a good rule of thumb. Resistant starch is a non-fermentable fiber that helps to increase good bacteria, decrease inflammation, and provide short-chain fatty acid butyrate that can boost gut healing and metabolism.





What is Resistant Starch?

Resistant starch is a fiber is not digested in the small intestine like most foods, which is how it gets its name. These starches move along undigested to the large intestine (colon) where they feed the good bacteria.


Resistant starch is formed from specific foods being fully cooked and then cooled for 24 hours. This cooling process after cooking allows for the resistant starch to form. The most popular foods include white potatoes, sweet potatoes, rice, and green bananas.



Why is Resistant Starch Good For Me?


High starch foods like potatoes and rice are high-glycemic when eaten immediately after cooking; but the cooling process allows for them to become "resistant" starch and therefore become a low-glycemic, high fiber food. You can warm these foods before eating again, but avoid heating hot enough to form steam. If you reheat at too high of a temperature the starch will turn back into a high-glycemic form.


Resistant starch also provides short-chain fatty acids, which are the preferred fuel for your intestinal system. Butyrate is the most abundant short-chain fatty acid and is one produced from resistant starch. Increasing the amount of butyrate in the gut by eating resistant starches can help to support optimal digestion, gut health, decrease inflammation, and even have a positive effect on metabolism.



1. Stay Full, Longer

Similar to high-fiber or high-protein diets, resistant starch can keep you full longer because it takes longer to digest. With the low-carb diet craze, you may be thinking it is best to cut out starches all together. Knowing the research and benefits of high-fiber foods is important. High fiber diets can help you to lose weight, cut cravings, and boost energy. (1)


Studies that used resistant starch from breads, corn, and wheat showed no difference in fullness; however, studies using resistant starches from potatoes and potato starch did show a significant increase in fullness after eating. (2)


2. Boost Mineral Absorption


Vital minerals like calcium, magnesium, and iron are commonly bound in foods making them tough for the body to break apart and absorb. When starch is fermented (digested) by gut bacteria in the colon, it creates an environment that allows these minerals to be absorbed. One study involving resistant starch showed a significant increase in absorption of iron and calcium from the large intestine. (3)


3. Regulate Bowel Movements


Bowel irregularity, including constipation and diarrhea, can be improved by adding resistant starch to your diet. This is believed to be because the good bacteria in our colon are the key to healthy digestion and regular bowel movements (4). Fiber and bacteria actively prevent diarrhea, cramping and help create soft bulky stools.


4. Cancer Prevention


Bowel cancer is the third most common form of cancer in the world (5). Much research on resistant starch is focused in this area and its benefits. The good news is that the positive results continue to pile up on each other. Studies compare the varieties and ratios of gut bacteria after fermenting resistant starches. Recent studies have found significantly fewer cancer-related proteins and acids in the stools of participants after they eat resistant starch. There is also research evolving on the ability of resistant starch to reverse an unhealthy gut environment. (6)





How to Include Resistant Starch in Your Diet


You can batch cook rice or potatoes for the week. Allow to cool 24 hours before eating. Keep stored in the refrigerator and add to salads, stir fries, casseroles, wraps, etc. Remember you can "warm" these foods again, but avoid heating to a point where steam forms because it can reverse the resistant starch formation.


Another easy way to incorporate resistant starch into your diet is through raw potato starch. You can find this at a health food store or online. Again, remember if you’re using raw potato starch that heat will destroy the benefit, so add after cooking or add to a cold food like a smoothie.


  • Add 2 Tbsp. raw potato starch in your smoothie or yogurt

  • Thicken puddings or sauces with a small amount of potato starch

  • Mix potato starch to almond or coconut milk beverages

  • Add sliced green banana to smoothies or overnight oats

  • Incorporate plantains into stir-fries, salads, or wraps

  • Mix precooked (and fully cooled 24 hours) potatoes or rice to your meal




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Liz Riesen, Registered Dietitian

specializes in digestive and hormone imbalances. Often these conditions coexist and share common disruptive symptoms including mood changes, bloating, pain, irregular cycles, inflammation, and more. Liz is trained in identifying and healing food sensitivities, as well as balancing hormones naturally through nutrition and lifestyle.


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