Carbs, amylum, polysaccharides, call it what you will, starch in all its forms has gotten a bad rap lately. Some of this negative attention is valid, as excessive starch in the diet can contribute to many health problems, not to mention gut issues.
The truth is that not all starch is bad, however, and one starch in particular called resistant starch (RS) has been gaining a lot of attention as it has been shown via research to be extremely beneficial to overall health.
Ironically, it is especially helpful for those with gut-related problems. This may seem hard to believe at first given that many forms of starch are avoided on gut healing diets like GAPS.
Resistant starch is a type of starch that does not break down. It literally “resists” digestion, instead of being absorbed as glucose like most starches. Instead, resistant starch travels through the small intestine to the colon where it is turned into beneficial, energy-boosting, inflammation squashing short-chain fatty acids by intestinal bacteria.
But, be wary as all forms of resistant starch are not the same!
Four Types of Resistant Starch
RS Type 1 – Starch that is bound by fibrous cell walls and therefore resists digestion, such as beans, legumes and grains, and nuts/seeds.
RS Type 2 – Indigestible due to its high amylase content when in its raw forms, such as found in potatoes, green bananas, tiger nuts, and plantains. Heating or over-ripening these foods renders the starch to be no longer indigestible though some reforms when cooled.
RS Type 3 – This type of resistant starch is the result of a process called retrogradation- when starches are cooked and then immediately cooled, which allows the digestible starch in some foods like rice, potatoes, and beans to be more resistant to digestion.
RS Type 4 – Industrial resistant starch that does not occur in nature. It is man-made via a chemical process and should be avoided.
Traditionally, it was believed that starch was fully digested and absorbed in the small intestine, but we now know this is not true.
At least 10% of the total starch in a typical Western diet is resistant starch, which acts very much like fermentable fiber. In general, starchy foods that contain RS Type 1 and RS Type 2 will yield greater amounts of resistant starch than any other foods, especially compared to fully cooked starches. Therefore, how a specific food is prepared can determine how much resistant starch it will contain.
The research has shown that in general, moderate levels of resistant starch intake is well tolerated by healthy people, and also provides many benefits to improve some of the most common health issues many people face today, such as:
- Stabilizing blood glucose levels and increasing insulin sensitivity
- Improving cholesterol and triglyceride levels
- Reducing appetite and increasing satiation, which can lead to weight loss and easier weight maintenance
Although resistant starch has many benefits to the entire body, it most notably has been studied for its positive effects on gut health.
RS and the Gut
Our gut harbors hundreds of different species that we are still learning about, but in the last few decades, we have discovered that specific bacteria and especially the quantity of them can make a huge impact on our overall health and wellbeing. For example, bacteria in the small intestine outnumber the body’s cells 10 to 1, so taking this into consideration, that makes us only 10% human!
The main reason why resistant starch is so beneficial is that it feeds the friendly bacteria in your colon, turns them into important short-chain fatty acids, such as butyrate (known to help reduce inflammation) and is extremely helpful in cases of autoimmunity, IBS, colitis, and allergies
Resistant starch acts and is the preferred energy source for cells lining the colon. Researchers from the RIKEN Center for Integrative Medical Sciences found “that the guts of mice with colitis increased in regulatory T cells, and their inflammatory symptoms improved after they were given butyrate in their diets.”
Other gut supportive benefits of resistant starch include:
- Maintenance of normal gut function – motility, recycling of waste products, bile acids, water and increase electrolyte absorption
- Increase good bacteria (flora) which protects against the growth of bad bacteria and pathogens
- Vitamin production of biotin, folate, and vitamin K – which can only be produced through bacteria
- Increase immunity – Roughly 80% of immunity is located in the gut
- Enhancing breakdown and elimination of toxins
A Word of Caution
If you’re not used to consuming resistant starch or have digestive problems, I suggest adding it in slowly to your diet as it can cause gas and discomfort while the body becomes used to it!
There is also some concern around resistant starch exacerbating digestive issues for some. If you’re working on healing from any digestive or GI illness or infection/ bacterial overgrowth, such as SIBO (small intestinal bacterial overgrowth) or IBS, I don’t recommend introducing resistant starch until one is in at least the partial remission stage as it may add to the fermentation taking place in the intestines, especially the small intestine (where you do not want this happening). Although everyone is different, so you may experiment by adding in low amounts of resistant starch and see how it reacts with your body before introducing more.
How to Safely add Resistant Starch to Your Diet
Resistant starch can be obtained either through food or supplements. Most common food sources include:
- Retrograded potatoes (cooked and then cooled such as fermented potatoes)
- Green bananas
- Legumes (cooked and cooled)
- Parboiled rice (including wild rice)
Supplement sources include:
- Potato starch, NOT potato flour (where to find)
- Plantain flour (where to find)
- Green banana flour (where to find)
- Cassava starch/tapioca (where to find)
- HI-MAIZEⓇ Flour (not cornmeal, cornflour or cornstarch)
Note: arrowroot is not high in the resistant type of starch, contrary to popular belief. On the other hand, teff, a lesser-known but extremely nutritious gluten-free grain, is high in resistant starch.
Potato starch and more recently, banana flour are probably the most common and researched resistant starch supplements, although any of these can be used. Remember, although these foods are starches, they are not being absorbed so they are not contributing to your daily carbohydrate consumption nor are they a significant source of calories. There is also no need to worry about spikes in blood glucose or insulin with these starches either.
One tablespoon of retrograded potato starch contains 8 grams of resistant starch and is very economical as a supplement source. Start small with a 1/2 tablespoon and slowly work your way up allowing several days to a week before increasing consumption to know how your body reacts with the introduction. You can mix this with other food, or in water alone. Some gas and bloating can be expected but should subside over time. When side effects are stabilized, you can safely work your way up to 30 grams of resistant starch. Note, that for some this may be too much to handle, so go at your own pace. If symptoms persist, this may be a sign that you may have other intestinal issues present.
Most healthy people will tolerate resistant starch just fine if slowly introduced, and will eventually start to see some great benefits from regular use. It may take some time (a few weeks) until you can notice health improvements as your body adapts to the starch and converts it over to the usable short-chain fatty acids.
(1) Gut bacteria’s fatty acid boosts immune system, reducing inflammation
(2) Promise for Improving Human Health
(3) A promising dietary agent for the prevention/treatment of inflammatory bowel disease and bowel cancer