Why reducing protein intake could promote healthy aging, according to new research

• Recent trends and advice have been recommending increased protein intake, especially for certain groups of people.
• A recent study, however, suggests that consuming less protein could help extend life span and have many health benefits by improving metabolism and reducing cellular damage.
• The study specifically suggests that reducing the consumption of certain amino acids, such as isoleucine and methionine, aids healthy aging, rather than simply reducing the amount of protein consumed.

Evidence so far has supported caloric restriction for its purported longevity benefits, but reducing protein intake has not been widely explored.

Now, a new review, published in the journal Cell Press Blue, suggests that restricting overall dietary protein intake or specific essential amino acids could help people achieve improved health span and increased longevity, similar to that achieved through calorie restriction.

The review, combing over 350 scientific papers on animal and human trials, outlines how restricting dietary protein and specific essential amino acids such as isoleucine and methionine helps promote healthy aging and extends life span.

The review examined the effects of protein restriction on several organisms, including microbes, mice, other animals, and humans, using observational studies, randomized controlled trials, and cell culture experiments.

Researchers found that eating less protein had many health benefits.

Consuming less protein helped the body burn more calories, reduced body fat, and better managed insulin levels by increasing levels of Fibroblast Growth Factor 21 (FGF21), a hormone that helps protect against aging.

A low protein diet also inhibited mTORC1 and activated GCN2, which are two key nutrient sensors that regulate cell growth and stress response, effectively telling the body’s cells to slow down aging and more efficiently clear cellular “trash” through autophagy.

Eating less protein also reduced the number of senescent or aging cells. Senescent cells are often called “zombie” cells because they are damaged cells that stop dividing (mitosis) but refuse to die, driving inflammation in the background.

Another important effect scientists observed of a low protein diet was the improvements in mitochondria, the powerhouse of the cell, and decreased reactive oxygen species (ROS) damage to tissues. In animal studies, scientists also saw that lab animals lived longer and had lower age-related frailty when fed less protein.

However, the researchers emphasized that protein needs should be personalized according to physical activity and age.