Less protein may slow aging in animal studies
Eating more protein is a popular piece of advice. But a review of more than 350 studies puts that conventional wisdom under pressure. Getting less protein appears to slow biological aging, at least in animal models.
Researchers at the University of Wisconsin-Madison analysed decades of research on the relationship between protein intake and aging. The review, published in Cell Press Blue, brings together several biological mechanisms that repeatedly appeared across the literature. Three amino acids stand out: methionine, isoleucine, and valine. Too much of these protein building blocks can activate growth-promoting signals that may contribute to inflammation and metabolic problems over time.
The hormone that rises with less protein
One of the most notable findings concerns the hormone FGF21. This hormone increases when protein intake is reduced. FGF21 helps the body adapt to changes in nutrient availability and influences how energy is used. Higher levels of this hormone were associated with longer lifespan in mice, particularly in male animals. Whether the same applies in humans has not yet been established.
Not the same advice for everyone
The researchers are clear: this is not a universal recommendation to eat less protein. Older adults often need more protein to prevent muscle loss. Pregnant women do too. And people who exercise regularly may handle larger amounts of protein better because physical activity changes how the body processes those nutrients.
For the large group of relatively sedentary adults, the review suggests that the current trend of adding protein to everyday foods offers little benefit and may be counterproductive. The findings do not prove that protein restriction extends human lifespan, but they point to biological processes worth investigating further.
Search terms to explore further: protein restriction lifespan | FGF21 metabolism aging | amino acids mTOR signaling