People of all ages can benefit from eating resistant starch from various sources. Resistant starch gives a host of benefits, including improved blood sugar control and better gut health.
Starch, a carbohydrate, consists of polymers made from connected glucose units and is used by plants to store energy. In the small intestine, starch can be rapidly digestible, slowly digestible or resistant to digestion.
Rapidly or slowly digestible starch is broken down into glucose by enzymes in the small intestine. The glucose then enters the bloodstream. Enzymes can’t break down resistant starch, however, so it passes through the small intestine intact and reaches the colon, where beneficial gut bacteria feast on it.
Specialised bacteria in the colon ferment resistant starch to produce short-chain fatty acids, which are important for colon health. These substances stimulate the production of gut hormones responsible for appetite control, helping us to feel full and reducing the urge to overeat.
Studies have shown that resistant starch also slows glucose absorption so that it’s released more gradually into the blood, which is particularly beneficial for people with type 2 diabetes. The short-chain fatty acids from fermentation improve insulin sensitivity, helping the body to use glucose more effectively and reducing blood sugar levels. They can also reduce inflammation.
There are different types of resistant starch. In cooked and cooled carbohydrates such as rice and pasta, the starch polymers lose their crystalline structure during cooking and become a less digestible, resistant form during cooling.
Seeds, whole grains and legumes such as lentils, chickpeas (see main picture) and beans all contain resistant starch. Uncooked oats and barley are also good sources, as are green bananas and plantains.
This article is an answer to the question (asked by Andrew Morris, Glasgow 'Should I be eating leftover carbs as I get older?'
To submit your questions, email us at questions@sciencefocus.com, or message our Facebook, X, or Instagram pages (don't forget to include your name and location).
Check out our ultimate fun facts page for more mind-blowing science.
Read more: