Researchers talked about the relationship of protein in the diet with aging

Protein is added to cereal, coffee, and even water. Scientists from the University of Wisconsin-Madison decided to find out what happens when the reverse diet changes, when the proportion of protein decreases. They reviewed more than 350 scientific papers. In some experiments, animals lived longer on this diet. In studies involving humans, scientists observed primarily changes in body weight and metabolism. About how the body reacts to a decrease in the proportion of protein in the diet and why the need for it depends on age and training — in the material "Izvestia".

What changes when the calorie content remains the same?

The authors of the review collected the results of laboratory experiments and studies involving humans. They were interested in what happens if you reduce the proportion of protein in the diet while maintaining its energy value. In experiments on fruit flies and rodents, life expectancy was sometimes increased without reducing caloric intake.

In one small human trial, 17 overweight or obese men were randomly assigned to two diets of comparable caloric content. In one, some of the protein was replaced with carbohydrates. After five weeks, the participants who received less protein had a decrease in body weight of about 2 kg, while the group with the usual diet remained the same. Such tests allow you to monitor the body's reaction to a change in diet for several weeks.

How the body reacts to a change in diet

In humans, FGF21 levels also increased with a decrease in protein content. For example, in a five-week study of healthy men without excess weight, the hormone concentration increased, and participants needed more energy with food to maintain their previous body weight. So far, such experiments describe a reaction to a change in diet over a period of several weeks. The effect of this reaction on human life expectancy remains to be seen.

Why is amino acid composition important?

The review separately examined methionine, isoleucine and valine. These are essential amino acids that the body must get from food. They are needed for protein synthesis and simultaneously participate in the regulation of metabolism.

In some animal experiments, changing the amount of one amino acid reproduced some of the effects that scientists observed with a decrease in the total protein fraction. This gives researchers the opportunity to check which components of the diet affect a particular metabolic rate.

Scientists have mapped the aging of blood vessels

The same amount of protein in two foods can produce different amounts of individual amino acids. Therefore, the composition of the diet is important in research, and when replacing part of the protein, it is also important which nutrient has taken its place. Both factors can affect how the body reacts to a diet.

How age and exercise affect the need for protein

Dudley Lamming, a co-author of the review and a professor at the University of Wisconsin-Madison, draws attention to the difference between people with a sedentary lifestyle and those who exercise regularly.

For older people, another important task is to maintain muscle mass and the ability to cope with daily exertion. The next question for researchers is under what conditions does a change in the proportion of protein have a lasting effect on metabolism and how does this change the condition of muscles. The answer will require long-term research involving people of different ages and with different levels of physical activity.