'Eat more protein,' they said — but less may mean longer life

High-protein diets have become a dominant health trend, flooding store shelves with beverages, cereals, snacks and powders all marketed as protein-packed. Now, new research suggests that cutting back on protein may actually support healthy aging and a longer life.

Healthline, a US health information outlet, recently cited a study published in the international journal Cell Press Blue, reporting that reducing protein intake may improve metabolism and lower inflammation and cellular damage. The research team analyzed more than 350 laboratory and animal studies on the relationship between protein consumption and aging.

The researchers focused particularly on three amino acids that make up protein: methionine, isoleucine and valine. Animal studies repeatedly found that restricting overall protein intake — or just these specific amino acids — extended lifespan. In one study, limiting valine intake alone in middle-aged male mice increased their lifespan by 23 percent.

Short-term studies in humans also observed improvements in blood sugar levels and reductions in body fat when protein intake was reduced. However, the research team noted that direct evidence linking such changes to longer human lifespans has yet to emerge.

In animal studies, reducing protein intake raised levels of substances involved in boosting metabolism and lowering inflammation, and also appeared to accelerate the removal of damaged cellular components. The research team said these metabolic changes may have contributed to healthier aging.

That does not mean cutting protein indiscriminately is the answer. Older adults in particular need adequate protein to prevent muscle loss, and those with sarcopenia or certain chronic conditions may actually need more. Pregnant women, children and adolescents, athletes, and people recovering from illness or injury also tend to have higher protein requirements.

In South Korea, insufficient protein intake among older adults has been flagged as a concern. Data from the Ministry of Health and Welfare's 2018–2022 National Health and Nutrition Examination Survey showed that while the overall population was not severely lacking in protein, adults aged 75 and older — women in particular — fell below the recommended daily intake.

The recommended daily protein intake is roughly 1 to 1.5 grams per kilogram of body weight. For those aged 60 and older, the guideline is about 60 grams per day for men and 50 grams for women.

Protein can be obtained from animal sources such as beef, pork, chicken, fish, eggs and milk, as well as plant-based foods including tofu, legumes and nuts. Spreading intake across three meals is preferable to consuming it all at once, and snacks can help make up any shortfall. As a reference, one egg contains about 8 grams of protein, 100 grams of meat or fish about 20 grams, one block of tofu about 24 grams, and a 200-milliliter carton of milk about 7 grams.