WASHINGTON: A review of more than 350 scientific studies suggests that consuming less protein may promote healthier aging and longer lifespan in some people, challenging the growing popularity of high-protein diets.
For years, protein-rich diets have been widely recommended for building muscle, supporting weight management and improving overall health.
However, researchers behind the review said many people may be consuming more protein than their bodies require, while the benefits of excessive intake may be overstated.
The analysis found that moderate protein restriction could improve metabolism, reduce inflammation and cellular damage, and activate biological processes linked to healthy aging.
The effects, however, vary depending on factors such as age, overall health and whether protein comes from animal or plant sources.
Researchers said high protein consumption—particularly amino acids such as leucine, commonly found in animal-based foods activates growth-related pathways including mTOR and IGF-1. While these pathways are important for muscle growth and tissue repair, especially in younger and physically active people, long-term activation later in life may contribute to faster cellular aging and increase the risk of age-related diseases.
The review also found that lowering protein intake may boost levels of fibroblast growth factor 21 (FGF21), a hormone associated with improved blood sugar control, increased energy expenditure and longer lifespan in experimental studies.
The researchers cautioned that protein restriction is not suitable for everyone. Older adults, athletes and people with certain medical conditions often require higher protein intake, making individualized dietary recommendations essential.
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The review, supported by the US National Institute on Aging, the Wisconsin Partnership Program and the University of Wisconsin–Madison, was published in the journal Cell Press Blue.
