Cutting protein may slow aging, 350-study review suggests

A review spanning more than 350 studies concludes that eating less protein may slow aging, improve metabolism and, in some cases, extend lifespan. Dudley Lamming of the University of Wisconsin-Madison and a colleague combed through the research and kept hitting the same biological patterns. Their analysis suggests cutting protein changes how cells sense nutrients, trims cell damage, and helps the body manage energy and blood sugar. It lands as a counterpunch to the protein-pumped era, where the macro shows up in everything from cereal to coffee.

Lamming isn't anti-protein. He's clear that active people get real benefits, saying it's “absolutely crystal clear that there are benefits of protein to muscle growth and exercise response of active individuals.” The problem is everyone else. Most people aren't highly active, he says, and are “likely consuming more protein than they actually need, which probably has negative health consequences.”

The review doesn't prove that less protein means a longer life. But recent clinical trials found that people who ate less protein dropped weight, shed body fat and improved fasting blood sugar — even while eating more total calories. This year, US authorities updated their guidance to recommend 1.2 to 1.6 grams of protein per kilogram of body weight, or 0.5 to 0.7 grams per pound, nearly double the previous amount. Older adults in particular are being told to load up to protect their muscles.

Lamming's team doesn't write that off. Muscle loss with age raises the risk of weakness and falls, and extra protein plus exercise helps fend that off. Their fix is personalization: tailor protein advice to both age and physical activity. “We probably need to personalize protein recommendations based not just on age, but also on how physically active people are,” Lamming said. The review also flags pregnant women as needing more protein.

One mechanism doing the heavy lifting is fibroblast growth factor 21, or FGF21, a hormone that climbs when protein intake drops. Higher FGF21 can rev up energy use, keep blood sugar steady and dial down inflammation. Mice with more of it lived longer, especially males — though whether humans follow suit is still unknown. Protein totals may not be the whole story either: the review points to three amino acids — methionine, isoleucine and valine — that in excess switch on growth pathways tied to obesity, inflammation and age-related disease.

Not everyone is sold. IBTimes Australia, as reported by Ground News, said scientists want more and longer human trials before anyone rewrites dietary advice.