Foods rich in resistant starch cause a lower ‘sugar spike’ than those containing other carbohydrates.

Some green bananas.

Resistant starch, as its name suggests, is not very digestible: partially resists breakdown by digestive enzymes in humans. Therefore, as it is not fully hydrolyzed, it cannot be absorbed in the small intestine and passes into the large intestine. There it can be fermented by the intestinal microbiota. In this way, acts as a prebiotic and stimulates the growth and activity of beneficial bacteria in the colon.

Some media advise us to eat foods rich in carbohydrates cooled, and reheated if necessary to eat them hot, to thus increase the amount of resistant starch we eat and benefit from its many beneficial effects. Next, we will see what is true about its benefits and how to increase your intake.

What is it and where to find it

Resistant starch is classified into five groups. Some are found naturally in foods such as legumes, whole grains, green bananas and some types of corn. Others, on the other hand, are artificially created by the food industry and are found in some processed foods.

Finally, there is a type of resistant starch that is formed during the retrogradation of starch, mainly in gelatinized starches obtained after cooling. It is characteristic of foods rich in carbohydrates that have been cooked and cooled later.

Health effects

Resistant starch has been credited with numerous positive health effects. In various clinical trials it has shown beneficial effects similar to other prebiotics. Thus, it appears to have positive effects on preventing constipation or reducing the incidence of some types of cancer like the colon.

In addition, they are currently studying its effects on obesity, as it appears to have a satiating effect. This can lead to a decrease in energy intake and therefore a reduction in body weight. In addition, if we transform that digestible starch into resistant starch by cooling some foods, we will be ingesting fewer calories than if we do not transform it (if it is not digested, it is not absorbed).

Resistant starch has been shown to play an important role in lowering blood glucose concentrations, especially in subjects with excess body weight and at risk of developing diabetes. It is a property accepted by the European Food Safety Agency (EFSA).

Specifically, the EFSA states that the substitution of digestible starches for resistant starches in a meal contributes to reducing the increase in blood glucose after eating (when the final resistant starch content represents at least 14% of the total starch). Therefore, its intake is especially interesting in people with insulin resistance and type 2 diabetes mellitus.

There are several mechanisms by which it could exert this effect on glucose concentrations. The digestible starch is hydrolyzed to glucose, which is absorbed in the small intestine and finally reaches the blood, raising its concentrations. On the other hand the Resistant starch is not fully digested, resulting in less glucose being absorbed, thus generating a lower rise in blood glucose.

Another potential mechanism involved may be the production of short-chain fatty acids generated by bacteria in the colon when fermenting it, which by a mechanism not yet fully understood can help regulate blood glucose levels.

Currently, there are no official recommendations on the optimal or minimum daily intake for resistant starch. In addition, the data on its intake by the population are not very precise. However, to get an idea of ​​how much we eat, we present some data.

In a study carried out in the United States, it was observed that the average intake of resistant starch in its population was of 4.6 grams per day in men and 3.3 grams in women. In Europe there are no recent data, but some studies showed an intake similar to that of the United States, far from ingest in China (almost 15 grams / day).

How to increase your intake

First of all, we can include foods rich in resistant starch in a “natural” way, such as legumes, whole grains, or underripe banana.

Another way to increase your intake is to chilling some foods that have digestible starch like rice, pasta, or potatoes after cooking. If this cooling is done in the refrigerator, the amount of resistant starch increases more than if it is done at room temperature.

In addition, refrigerating it for longer increases the formation of resistant starch. For example, we can cook food (rich in starch) the day before and keep it in the fridge until consumption. It is important to mention that its reheating reduces the amount of resistant starch, so it is advisable not to reheat it at very high temperatures. to avoid reducing their quantity too much.

In addition, the food industry, which is constantly creating innovative food products with health benefits, has developed foods rich in resistant starch, which can also be used to increase intake if the consumer considers it so.

Finally, as a conclusion, it should be remembered that the intake of resistant starch is beneficial to health, like any prebiotic, but it has also been shown that it can be especially beneficial in some diseases such as insulin resistance or type 2 diabetes mellitus. Finally, we must add that more studies are needed to determine its beneficial effects on other diseases such as obesity.

* Saioa Gómez Zorita is a professor at the University of the Basque Country. Researcher at the Network Biomedical Research Center for the Physiopathology of Obesity and Nutrition (CiberObn) and at the Bioaraba Health Research Institute, University of the Basque Country / Euskal Herriko Unibertsitatea.

* Maria Puy Portillo is Professor of Nutrition. Center for Biomedical Research Network on the Physiopathology of Obesity and Nutrition (CIBERobn), University of the Basque Country / Euskal Herriko Unibertsitatea.

** This article was originally published on The Conversation