Resistant starch
What is resistant starch, how can it benefit your health and how to add it to your diet.
Resistant starch is a type of carbohydrate that acts in a similar way to fibre in our bodies. It is a type of starch that can’t be digested by us. Instead, it travels to the colon (large intestine) where it is fermented by beneficial bacteria. This produces compounds including gases and short chain fatty acids which have metabolic and health benefits for our bodies.
What is resistant starch?
Starches are a major source of carbohydrates in our diet, found in a wide range of plant-based foods like grains, potatoes, roots, and legumes. Starch in the food we eat can be classified into three groups. Rapidly digestible starch, slowly digestible starch, and resistant starch.
Rapidly digestible starch: Breaks down quickly, causing a rapid rise in blood glucose.
Slowly digestible starch: Breaks down gradually, providing a steady glucose release.
Resistant starch: Resists digestion in the small intestine and is fermented in the colon, creating short chain fatty acids (SCFAs) like butyrate, acetate, and propionate.
What are the benefits of resistant starch?
One of the main reasons many people have heard of resistant starch is for its potential weight control benefits. Because resistant starch isn’t utilizable by our bodies, having resistant starch in a meal reduces the calorie density of the entire meal compared to the same volume meal without resistant starch while helping us feel less hungry.
Having resistant starch in our diet has been shown to help with satiation after a meal, making it less likely for us to over eat. It also helps to keep our blood sugar balanced reducing blood sugar spikes after meals and may improve our cellular sensitivity to insulin.
Resistant starch provides fuel for the good bacteria in our colon and helps to improve this population. This allows us to harness the health benefits of beneficial gut bacteria rather than fueling the less desirable ones.
When our gut bacteria digest resistant starches, they produce compounds including gases and the short chain fatty acids (SCFAs), butyrate, propanoic acid and acetic acid.
Butyrate is important for supporting the health of our gut. It is the preferred fuel for the cells that make up the intestinal lining of our colon (colonocytes). This is important for a healthy and well-functioning colonic barrier.
Propanoic acid and acetic acid help to lower the pH in the colon, this supports beneficial microbe growth and hinders less desirable microbe growth.
Resistant starch also helps reduce inflammation and may help reduce the risk of colorectal cancer through its promotion of gut health as well as helping with regular bowel movements.
SCFAs can help reduce cholesterol and triglyceride levels in the blood, and resistant starch acts similar to other fibre foods with prebiotic properties, stimulating the growth of beneficial gut microbes including bifidobacterium and lactobacillus strains.
The 4 types of resistant starch
Type 1 is found in seeds, grains, legumes and resists digestion because it is bound inside the fibrous cell walls of these foods.
Type 2 is found in some starchy foods like raw potatoes and green bananas.
Type 3 occurs when starchy foods like potatoes and rice are cooked and then cooled. The cooling down turns some of the digestible starches in these foods into resistant starches.
Type 4 is man-made resistant starch, formed through chemical processes.
Foods can have more than one type of resistant starch and depending on how the food is prepared, the amount of resistance starch can vary.
Foods containing resistant starch
Green bananas – as a banana ripens the amount of resistant starch reduces.
Legumes – chickpeas, lentils, beans
Seeds (in smaller amounts) - pumpkin seeds, chia seeds, hemp seeds, flax seeds, cashews
Grains – oats, corn, rice and pasta (ideally wholegrain), resistant starch increases when these foods are cooked and then cooled.
Potatoes and sweet potatoes – cooked then cooled. Sweet potatoes contain less resistant starch after cooking and cooling but have lots of other great nutrients as well.
Cooking and then cooling starchy foods like potatoes, rice, pasta and corn changes the structure of the starches and creates resistant starch. These foods can be eaten cold or reheated without significant changes to the amount of resistant starch present.
Adding resistant starch containing foods to your diet can have many beneficial effects including helping digestion, gut health, metabolic health, and helping you feel fuller for longer with more balanced energy levels. With its ability to nourish our microbiome and stabilise blood sugar, resistance starch can be a great addition to any balanced diet.
