By now you are probably more than familiar with the idea that what we eat can affect our microbiome and in turn, our overall health. Fibre is talked about a lot in regards to gut health, but there is one particular type of fibre I wanted to draw your attention too, and that's resistant starch. As our knowledge of the gut continues to evolve, I suspect you’ll be hearing a lot more about it. Here’s everything you wanted (and need) to know about resistant starch and how you can include it in your diet.
What is resistant starch?
Resistant starch is a non-digestible, prebiotic starch. The majority of starches you eat from carbohydrates are broken down by enzymes in our small intestines into sugar, which is then absorbed into the blood. However, we can’t absorb all types of starch this way. A group of starches, known as resistant starch, aren’t able to be fully absorbed in the small intestine and travel undigested to the large intestine (or colon) where bacteria there ferment it.
There are five different types of resistant starch and multiple types of resistant starch can co-exist in the same food. Additionally, the levels of resistant starch in food can change depending on how foods are prepared. For example, the amount of resistant starch in a banana will decrease as it starts to ripen, and cooked rice that has been cooled is higher in resistant starch than rice that was cooked and not cooled.
Why is resistant starch good for me?
First of all, as bacteria in the colon are required to ferment resistant starch, it acts as food or ‘feeds’ our gut bacteria and promote bacterial diversity, which benefits everything from our immunity to our mood.
Additionally, when bacteria digest resistant starches, they form several compounds, including gases and short-chain fatty acids. Short-chain fatty acids are produced when the fibre is fermented in the colon and short-chain fatty acids then promote the production of compounds such as butyrate. Butyrate is the preferred fuel of the cells that line your colon, meaning that resistant starch indirectly fuels the cells that line your colon.
As well as looking after our gut health, research has shown butyrate has a role as an anti-inflammatory agent, and that resistant starch may also assist with appetite regulation and insulin sensitivity.
Where can I find resistant starch and how much should I be having?
The highest foods in resistant starch are: unrolled, uncooked oats, cooked and cooled potatoes, rice and pasta, green banana flour, potato starch, legumes, lentils, barley, tiger nuts and lupins.
Great ways to include resistant starch in your diet are to make overnight oats for breakfast, cook extra potatoes or rice at dinner to add to your lunch the following day, bake with tiger nut flour or add legumes to salads and stews.
The general recommendation for resistant starch is approximately 20g per day. Ideally, you would meet this target gradually through the day, as opposed to all in one meal. If you aren't used to eating high fibre or resistant starch foods, it best to start small and gradually increase the amount you are having.
To get the most from resistant starch, choose whole, unprocessed sources of carbohydrate such as whole grains, fruits, vegetables, and beans/legumes. As always, my advice is to stick to whole foods!