Scientists have changed their view on the benefits of high protein intake
Protein is considered one of the main components of a healthy diet, and products with its high content can be found in almost any store today. However, despite its important role for the body, more and more research shows that the principle of "the more protein, the better" may not always work. About why excess protein is not necessarily beneficial, what role physical activity plays and who really needs more of this nutrient, is in the "Izvestia" material.
Protein is necessary for the body, but more is not always better.
Protein helps build muscles, keeps you feeling full longer, and is one of the essential nutrients. That is why people, especially in the elderly, are often advised to increase their intake. However, studies published in recent years have forced scientists to take a fresh look at the effects of protein on health.
Dudley Lamming, professor at the University of Wisconsin-Madison and lead author of the study
We consider protein to be a useful product, but there have been many studies showing that if we look at large populations over the decades, people who consumed more protein during those decades had higher rates of age-related diseases.
The researcher said that initially he was not going to look for the negative effects of the protein. His attention was drawn to the contradiction between the widespread perception of the benefits of high-protein nutrition and the results of long-term observations. They showed that people who consumed more protein over the years were more likely to develop cancer, diabetes, and cardiovascular disease.
To figure this out, Lamming and his colleagues analyzed more than 350 studies. Most of them were conducted on mice and other laboratory animals, but the review also included several randomized trials involving humans. The work was published in the Cell Press journal.
What happens if there is too much protein?
Clinical studies have shown that limiting protein intake was accompanied by a decrease in body weight and adipose tissue. In one study involving people with type 2 diabetes, insulin sensitivity also improved. At the same time, as Lamming emphasizes, this effect cannot be explained by simply reducing the caloric content of the diet.
Dudley Lamming
In fact, because dietary protein has a satiating effect, people in our and other studies consumed more calories when they followed a protein-restricted diet. But at the same time, they lost weight, and this is because energy consumption increases.
According to studies in mice, a possible explanation for this mechanism was the hormone FGF21. When the amount of protein in the diet decreases, the liver begins to produce this hormone, which affects the brain and triggers a process called "beiging." This process, according to Lamming, instructs adipose tissue to stop simply accumulating fat and start metabolizing and burning it for energy.
At the same time, the researchers emphasize that we are not talking about a dangerous protein deficiency. In the studies reviewed, its share in the diet was usually reduced from about 16-17% to 7-9% of the total caloric content.
Dudley Lamming
We are not talking about limiting protein intake to an unhealthy level that causes a lack of protein. In most cases, we are talking about limiting protein intake to the recommended daily allowance set by the World Health Organization, which is about 0.8 grams per 1 kg [body weight].
The authors also note that in experiments on rodents, similar effects were observed with the restriction of individual amino acids — methionine, isoleucine and valine. This was accompanied by a decrease in body fat, improved blood sugar control, and increased life expectancy.
Exercise can change the equation.
Despite the results, the researchers do not believe that everyone should drastically reduce their protein intake. According to Lamming, regular physical activity can significantly change the effect of high-protein nutrition on the body.
Dudley Lamming
We believe that dietary protein has a negative impact on the metabolic health of people who lead a sedentary lifestyle, as well as the general population, since the majority of the population leads a fairly sedentary lifestyle. But perhaps people who exercise need more protein to build muscle mass, and then they may not have such negative metabolic effects.
So far, this conclusion is based only on studies in mice, but scientists suggest that physical activity may protect the body from the potential adverse effects of increased protein intake. In the coming years, the team plans to test this hypothesis in studies involving both animals and humans.
Who really needs more protein
According to the researchers, the results of the work do not mean that protein is harmful or that it should be limited to everyone without exception. On the contrary, for people who exercise regularly, increased protein intake can be beneficial for maintaining and growing muscle mass. Scientists expect to verify this in future studies.
For people who lead a sedentary lifestyle, Lamming suggests a simpler approach: if possible, choose regular foods instead of their artificially high protein options.
Dudley Lamming
As our research shows, for an ordinary person who does not exercise, consuming more calories in the form of protein will be harmful.
At the same time, the researcher separately emphasizes that the rejection of excess protein should not replace physical activity.
Переведено сервисом «Яндекс Переводчик»
