What is Resistant Starch?

What is resistant starch?

Resistant starch is a type of carbohydrate produced by plants that behaves like dietary fibre in the body. Unlike other types of starch, resistant starch (RS) passes through the small intestine undigested and moves on to the large intestine where it is broken down and fermented. Like regular dietary fibre, resistant starch plays an important role in digestive function.

 Where is resistant starch found?

Resistant starch can be found naturally in foods such as legumes, unripe bananas, and cooked and cooled potatoes. Some processed foods such as breakfast cereals and breads also contain added resistant starch called Hi-Maize® derived from corn.

 Why is resistant starch not digested?

There are several different reasons why resistant starch escapes digestion:

  1. The tough outer coating of seeds and grains it is found in make it physically inaccessible to digestive enzymes.
  1. It may be structured in such a way that digestive enzymes are prevented from breaking it down. This type of resistant starch is found in raw potatoes and unripe bananas.
  1. The cooling of starchy foods which have been heated can lead to the formation of crystals which are resistant to digestion. This type of ‘retrograded’ starch is found in foods like cornflakes or potato salad.
  1. Chemical treatment can sometimes make starch resistant to breakdown by digestive enzymes.

What are the health benefits of resistant starch?

Digestive health

A healthy digestive system is essential for overall quality of life. Resistant starch positively effects digestive health by:

  • Increasing stool bulk, acting as a mild laxative and promoting regularity;
  • Functioning as a prebiotic, which promotes the growth and protection of beneficial bacteria in the bowel and suppresses harmful bacteria;
  • Reducing pH in the intestine which subsequently reduces production of potentially harmful substances; and
  • Increasing levels of short chain fatty acids (SCFA) (particularly butyrate) which encourage the growth of normal cells and inhibit the formation of cancer-forming cells in the bowel.
  • Improves your microbiome balance within the gut.

Improved glycaemic response

Resistant starch may also reduce or delay increases in blood glucose levels following a meal by slowing the rate and amount of carbohydrate digested, making it ideal for people with diabetes. This slower, more controlled glycaemic response also helps suppress hunger and keep energy levels up throughout the day.

Weight control

Resistant starch may also benefit individuals who are trying to achieve and maintain a healthy body weight. Due to its indigestible nature, resistant starch provides less kilojoules (calories) than digestible starch and should be included as part of a healthy balanced diet.

How much resistant starch do I need?

The Division of Human Nutrition in Australia recommends that 20g(1) of resistant starch should be eaten each day to obtain the health benefits related to its consumption. It is estimated, however, that intake in developed countries is only around 3-7g per person per day.

1 CSIRO Division of Human Nutrition (1996) Dietary Fibre, Non-Starch Polysaccharides and Resistant Starch – A Review. Food Australia, 48(3).

 This information is for the general interest of readers. Please consult your Doctor or Dietitian for advice on your personal dietary requirements.