We are often told that potatoes, pasta and rice are the demon white carbs that we need to cut back on if we want to avoid piling on the pounds or preventing a bloated tummy. But look closer and you will find that they can actually help balance your appetite and improve digestion if you eat them in the most optimal way.

The secret is in increasing the levels of resistant starch found in these foods.

What is the difference between starch and resistant starch?

You are probably aware that starches are complex carbohydrates that are broken down into glucose and absorbed into the bloodstream from our small intestine. On the other hand, resistant starches are carbohydrates which are not digested or broken down and remain in the gut. They are therefore considered a fibre. Resistant starch also plays an important role in providing food for the good bacteria in our gut which in turn bolsters the diversity in the gut microbiome.

The biggest source of resistant starch is in green unripe bananas. I wouldn’t recommend eating these raw but you can buy green banana flour and pasta in some health food shops. Even eating harder and less ripe bananas is better than eating the sweeter riper ones in terms of levels of resistant starch and helpful fibre.

Beans, chickpeas and lentils are also a good choice for resistant starch. These are easy to add to the diet through eating hummus or dhal, or by adding a tin of beans or lentils to pies, soup or casseroles.

Not many people realise that foods like potatoes, pasta and rice have high levels of starch when hot, but are great sources of resistant starch when they are cold.

This is because the starch changes its structure when it’s heated and cooled, morphing from the digestible starch we associate with these high carb foods to the beneficial fibrous resistant starch. Levels of resistant starch in potatoes and rice nearly triple after cooking and left to cool. So, eating cold pasta, potatoes and rice in the form of pasta salads, potato salad and rice salad is so much better than eating them hot.

If the idea of eating cold potatoes, pasta and rice during the colder winter months makes you feel a bit chilly do not worry at all, there is a solution to this. You can heat these foods up again without damaging the newly created resistant starch. So, this could be a reheated pasta bake, risotto or mashed potato. Remember with rice you should only heat this up once to a piping hot temperature within 24 hours of first cooking it. Otherwise, there is a risk of food poisoning.

Diversity is important

There are three naturally occurring types of resistant starch. Try to include the full range of foods they are found in because, as they work in different ways, they are more effective when eaten in combination than separately.

Type 1 – naturally found in wholemeal or sourdough bread, seeds and pulses.

Type 2 – found in small waxy new potatoes and less ripe bananas.

Type 3 – Retrograded starch formed when starchy foods are cooked then cooled including potatoes, rice and pasta.

Resistant starch and gut health

Resistant starch functions as a prebiotic, which fuels the beneficial bacteria in the gut microbiome. The bacteria break it down into metabolites including short chain fatty acids (SCFA), which support a healthy digestive system. There are many types of SCFA but resistant starch fermentation specifically produces high levels of a SCFA called butyrate.

Butyrate is a wonderful little molecule that is fundamental to keeping the intestines functioning normally. It ensures the integrity of the cells lining our intestine, protecting against gut and other diseases including colorectal cancer. Think of butyrate as the key protector of gut DNA. Butyrate is also thought to play a role in reducing systemic chronic inflammation and can be neuroprotective to the brain.

Resistant starch and appetite

It is not just our digestion that benefits from eating more resistant starch. Research shows that resistant starch affects our appetite. It does this in two ways.

Firstly, it increases the body’s sensitivity to insulin. This means that blood sugar levels do not shoot up after eating resistant starch as easily as they can after eating digestible carbohydrates. This regulation of blood sugar levels, as well as protecting against Type 2 diabetes, can balance appetite and stop you reaching for a snack.

Resistant starch also increases the release of gut hormones which promote feelings of fullness, stimulated by those good old SCFAs you learnt about earlier. In this way, resistant starch can help to decrease appetite and short-term food intake so can help as part of a weight loss plan.

Roundup

If you enjoy pasta, rice and potatoes you don’t have to cut them out of your healthy eating plan entirely then cook them, cool them and then reheat them. So a convenient pouch of precooked rice will have plenty of resistant starch in it, even when reheated; and yes chips cooled and reheated are better for you than fresh chips! Use sense of course and enjoy these foods as part of a balanced diet. You will be increasing your fibre intake which will improve your gut health and can also balance your appetite!

References

• Dietary reference intakes: implications for fiber labeling and consumption: a summary of the International Life Sciences Institute North America Fiber Workshop, June 1-2, 2004, Washington, DC  
• Interactions between dietary fibre and the gut microbiota
• Measurement of resistant starch: factors affecting the amount of starch escaping digestion in vitro
• Effect of cooling of cooked white rice on resistant starch content and glycemic response
• Chilled Potatoes Decrease Postprandial Glucose, Insulin, and Glucose-dependent Insulinotropic Peptide Compared to Boiled Potatoes in Females with Elevated Fasting Glucose and Insulin
• Effects of potato resistant starch intake on insulin sensitivity, related metabolic markers and appetite ratings in men and women at risk for type 2 diabetes: a pilot cross-over randomised controlled trial
• Influence of resistant starch on the SCFA production and cell counts of butyrate-producing Eubacterium spp. in the human intestine
• Resistant starch and ‘‘the butyrate revolution’’
• Resistant starch: impact on the gut microbiome and health
• Food Starch Structure Impacts Gut Microbiome Composition
• Starch digestibility: past, present, and future
• Resistant starch in food: a review
• Resistant starch: promise for improving human health
• Non-Digestible Carbohydrate and the Risk of Colorectal Neoplasia: A Systematic Review
• Resistant starch: the effect on postprandial glycemia, hormonal response, and satiety
• Greater satiety response with resistant starch and corn bran in human subjects
• The potential of resistant starch as a prebiotic
• Dynamics of Human Gut Microbiota and Short-Chain Fatty Acids in Response to Dietary Interventions with Three Fermentable Fibers