Blog Post

Resistant Starch – The Things You Need to Know

Resistant Starch Rich Foods

Resistant starch has gained a lot of recognition over the last few years for the potential health benefits associated with it. Theoretically, it can be an easy way to improve overall gut health while resulting in a lot of other health outcomes too.

What Is It?

Starches are long chains of glucose found in carbohydrate-rich foods. Resistant starch is a form of starch that is resistant to digestion.

Basically, resistant starch is a unique form of fibre. It passes through the small intestine to the large intestine mostly undigested.

Types of Resistant Starch

Type 1: Physically inaccessibleType 2: Resistant granules
Cannot be broken down during digestion.

Naturally found in legumes seeds and wholegrains.
Contains high amounts of a polysaccharide known as amylase and is resistant.

Naturally found in unripe bananas, potatoes and some legumes. The more raw or uncooked these foods are, the higher the resistant starch content is. Unripe bananas are high in this type of resistant starch, but ripe bananas are not.
Type 3: RetrogradedType 4: Chemically modified
Cooking and then cooling certain starch-rich foods changes the starch and makes it more resistant to digestion.

Naturally found in cooked/cooled potatoes and rice.
Some companies have isolated and produced their own form of resistant starch. A great example of this is BARLEYmax from CSIRO.
Barley+ Cereal

How Can It Help?

Resistant starch can act as a prebiotic fibre. It can be used as a food source for the gut bacteria in the large intestine.

This typically has a positive impact on both the type and number of healthy bacteria in the microbiota.

It also helps to increase the amount of short-chain fatty acids in the gut too. In particular, it increases butyrate significantly. This has long been associated with positive health outcomes.

Although it is hard to measure, it looks like the average Australian consumes about 3-9g of resistant starch per day. Intakes of 15-20g have been linked with positive health outcomes. Most people likely would benefit from increasing their intake.

Insulin Sensitivity

Increased consumption of resistant starch appears to improve insulin sensitivity.

A combination of this and other aspects result in it reducing the increase in blood glucose levels after eating.

For context, research has indicated an average of a 3350% improvement in insulin sensitivity after just 4-weeks of consuming 15-30g of resistant starch per day.

The applications of this for somebody with diabetes could be huge. Management of the condition could be significantly improved with a few changes like this. Obviously, there are a lot of other things that can make a larger improvement, but this could be an easy win.


With IBS there is often a lot of focus on things like FODMAPs due to the effectiveness it has for most cases of IBS.

If FODMAPs does not work, there are a lot of other options to focus on such as stress management and manipulation of fibre types and amount.

But something that is less commonly spoken about is the role that things like bifidobacteria and butyrate play.

Those with IBS who experience pain have on aver 5x fewer bifidobacteria than those who do not experience pain.

People with IBS also typically have lower levels of butyrate.

These are two things resistant starch increases.

There is not a lot of research directly studying the impact on IBS when resistant starch intake is increased. But the theoretical mechanism for improvement makes sense.

If increasing resistant starch in a bid to help manage symptoms, it is worth slowly increasing rather than rapidly increasing. A sharp increase in total fibre intake often can make symptoms worse rather than better.

Weight Loss

Carbohydrates typically have 4 calories per gram. Resistant starch only has 2 calories per gram.

Therefore, resistant starch is lower calorie than other starchy equivalents.

Beyond that though, it helps with satiety. This typically results in people consuming fewer total calories.

Due to the combination of reduced appetite and it also being slightly lower calorie, it could be a useful tool as part of a well-designed fat loss approach.

Other Potential Benefits

There is also the potential that resistant starch can reduce the risk of bowel cancer.

Other digestive conditions such as inflammatory bowel disease and diverticulitis could also be improved too.

More research is needed, but there is some promise based on theoretical mechanisms and the research we have so far.

Practical Take-Away Points

Resistant starch can provide health benefits. It should not be the top priority though. There are a lot of other areas of nutrition worth prioritising above resistant starch.

If you wanted to improve your intake of resistant starch though, the following would be the best place to start:

  1. Focus on consuming legumes, seeds and/or wholegrains regularly.
  2. Consider having cooked and then cooled potato or rice. Consider having less ripe bananas.
  3. Consider having a man-made product like BARLEYmax. Some cereal options are fortified with this.
  4. Increase intake slowly. Increasing too quickly likely leads to symptoms like bloating and gas that otherwise could be avoided as your body gets used to the higher intake.
By Aidan Muir

Aidan is a Brisbane based dietitian who prides himself on staying up-to-date with evidence-based approaches to dietetic intervention. He has long been interested in all things nutrition, particularly the effects of different dietary approaches on body composition and sports performance. Due to this passion, he has built up an extensive knowledge base and experience in multiple areas of nutrition and is able to help clients with a variety of conditions. One of Aidan’s main strengths is his ability to adapt plans based on the client's desires. By having such a thorough understanding of optimal nutrition for different situations he is able to develop detailed meal plans and guidance for clients that can contribute to improving the clients overall quality of life and performance. He offers services both in-person and online.