If you think starches will make you fat and play havoc with your blood sugar, you’re not alone. Starchy foods have a bad reputation. But that reputation is undeserved for foods high in a particular kind of starch. We’re talking about resistant starch, a kind of fiber most abundant in beans and other legumes. It’s also found in whole grains, vegetables, seeds, green bananas, and nuts such as cashews and almonds.
Resistant starch gets its name because it resists fast digestion. The enzymes in our small intestines don’t break down these carbohydrates easily, which prevents a quick rise in blood sugar. It also means that more of these starches make it into our colons, where they act as prebiotics: substances that provide food for helpful bacteria.
When helpful gut bacteria are well fed, they multiply, creating a healthier microbiome. That’s the community of bacteria that lives in every person’s digestive tract. When we eat lots of resistant starch, we get more bacteria that make certain short-chained fatty acids, such as butyrate. These fatty acids are absorbed into our bloodstreams, where they travel through the body and even to the brain. Benefits may include improved immune function, lower inflammation, and positive effects on mental health, metabolism, and body fat.
Eating more fiber, including resistant starch, also directly improves digestive health, creating softer, bulkier stools, and reducing colon cancer risk.
The emerging science has led to a vast array of supplements that claim to supply resistant starch in pills and powders, but studies have shown no benefits from these products. And there’s no reason to think that a supplement could work as well as whole foods. After all, when you eat a bean or a nut or a vegetable, you get not just resistant starch, but all kinds of fiber, plus vitamins and minerals.
Here are some ways to get more resistant starch:
