Protein and Amino Acid Restriction May Unlock New Pathways for Healthy Aging, Major Review Finds
核心洞察
A comprehensive review of over 350 studies finds that dietary protein restriction can improve metabolic health, reduce cellular damage, and extend lifespan across diverse organisms.
The hormone FGF21 emerges as a central mediator, rising during low protein intake to boost energy expenditure, improve glycemic control, and lower systemic inflammation.
Specific amino acids—methionine, isoleucine, and valine—are identified as key drivers of growth signaling pathways that, when overconsumed, may accelerate age-related metabolic decline.
A sweeping new review published July 31 in Cell Press Blue synthesizes evidence from more than 350 studies and concludes that reducing dietary protein intake—or restricting specific amino acids—can improve metabolic health, slow cellular aging, and extend lifespan. The findings challenge recent recommendations that have urged higher protein consumption, particularly for older adults, and suggest that many sedentary individuals may be consuming more protein than their bodies need, with potentially negative health consequences.
“It’s absolutely crystal clear that there are benefits of protein to muscle growth and exercise response of active individuals,” said Dudley Lamming, the paper’s corresponding author at the University of Wisconsin-Madison. “But because most people are relatively sedentary, many people are likely consuming more protein than they actually need, which probably has negative health consequences.”
The review, titled “The Hallmarks of Protein and Amino Acid Restriction in Aging and Longevity,” draws on evidence spanning yeast, fruit flies, rodents, and human clinical trials to map how protein restriction (PR) and restriction of specific essential amino acids impact metabolic health, nutrient sensing, senescence, mitochondrial function, and the epigenome.
FGF21: A Central Metabolic Driver
One of the most consistent findings across studies is the role of fibroblast growth factor 21 (搜索) (FGF21), a hormone that rises when protein intake is low. FGF21 increases the body’s energy expenditure, improves blood sugar control, and reduces inflammation. Studies in mice have shown that animals with higher FGF21 levels lived longer than normal mice, with the benefit more pronounced in males than females. Eating less protein raises FGF21 levels in humans as well.
“FGF21 can increase the body’s energy expenditure, improve blood sugar control, and reduce inflammation,” the authors note, describing the hormone as a central mediator of the metabolic benefits observed during protein restriction.
Key Amino Acid Drivers: Methionine, Isoleucine, and Valine
The review pinpoints three specific amino acids—methionine, isoleucine, and valine—as primary drivers of growth signaling pathways that, when overconsumed without corresponding physical activity, promote inflammation, metabolic dysfunction, and accelerated aging. Restriction of these amino acids recapitulates many of the benefits of broader protein restriction.
“These studies show that the amount of protein sedentary people are eating today may have negative health consequences, at least at the population level,” Lamming said.
In short-term human studies, reducing dietary branched-chain amino acids (BCAAs) by 60–75% for periods ranging from seven days to four weeks improved insulin sensitivity and glucose and insulin homeostasis. A four-week BCAA restriction trial in people with metabolic syndrome also raised circulating FGF21 and reduced mechanistic target of rapamycin complex 1 (mTORC1) signaling in white adipose tissue.
Calorie-Independent Benefits
The review demonstrates that protein restriction yields measurable metabolic benefits without requiring overall caloric restriction. Several recent clinical trials in humans have shown that reducing protein intake can reduce weight and fat mass and improve fasting blood sugar, even though protein-restricted individuals tend to eat more calories. Increased energy expenditure has been reported during protein restriction in lean men and in experimental models.
The Activity-Dependent Nuance
The authors emphasize that regular exercise appears to insulate active individuals from the metabolic risks associated with high-protein diets. Athletes often consume large amounts of protein without developing metabolic diseases, likely because physical activity directs amino acids toward muscle remodeling rather than pro-aging signaling pathways.
“Recent recommendations have encouraged people to eat more protein, but they’ve also encouraged people to exercise more,” Lamming said. “We probably need to personalize protein recommendations based not just on age, but also on how physically active people are.”
Implications and Cautions
The official Recommended Dietary Allowance remains 0.8 grams of protein per kilogram of body weight daily for adults, while expert groups routinely recommend 1.0 to 1.2 grams per kilogram for adults aged 65 or older. However, high protein intake has been associated with an increased likelihood of diabetes (搜索), cancer, overall mortality, and cardiovascular mortality in observational studies such as NHANES, though the authors caution that such studies cannot establish causation.
The researchers also note that protein or amino acid restriction could be harmful for pregnant women, growing children, people recovering from injuries, individuals consuming insufficient calories, and older adults who already have inadequate protein intake. The effects of protein restriction on human lifespan remain unknown, and the laboratory promise has not yet been translated into dietary guidance.
This work was supported by the National Institute on Aging, the Wisconsin Partnership Program, and the University of Wisconsin–Madison.