Resistant Starch
The starch that acts like fibre — it escapes digestion, feeds gut bacteria, and produces butyrate that heals the gut wall.
— Definition
Resistant starch (RS) is starch that resists digestion in the small intestine and reaches the colon intact, where it is fermented by gut bacteria into short-chain fatty acids (SCFAs) — primarily butyrate, propionate, and acetate.
— In Detail
There are 4 types: RS1 (physically protected in intact grains), RS2 (raw starch granules — raw potato, green banana), RS3 (retrograded starch — formed when cooked starch is cooled), RS4 (chemically modified). RS3 is particularly relevant: cooking and cooling rice, potatoes, or legumes increases RS by 3–5×. Reheating partially destroys it. Fermentation further increases bioavailability of minerals in RS-rich foods. Traditional Indian practices of soaking, fermenting, and cooling grains inadvertently maximised RS content.
— Why It Matters
RS is one of the most powerful gut health tools in whole foods. Butyrate produced from RS fermentation: heals leaky gut, feeds colonocytes (colon cells), reduces colorectal cancer risk by 50% in animal models, and suppresses appetite by stimulating PYY and GLP-1 hormones. Many heirloom grains (barnyard millet, black rice) have significantly higher RS than modern equivalents.
— Related Terms
— See in Field Guide
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