Longevity: Eating Less Protein Linked to Healthy Aging in New Studies

• New research suggests reducing protein intake may support healthy aging and longevity.
• Protein restriction may improve metabolism, reduce inflammation, and reduce cellular damage.
• Protein needs vary by age, activity level, and overall health, so reducing protein intake may not be appropriate for everyone.

New research suggests eating less protein — particularly certain amino acids — may support healthier aging and longevity.

A new review, published July 31 in Cell Press Blue, analyzed more than 350 laboratory and animal studies and found that reducing protein intake may improve metabolism while reducing inflammation and cellular damage.

The potential benefits, however, may depend on factors such as age, activity level, and overall health.

“It’s absolutely crystal clear that there are benefits of protein to muscle growth and exercise response of active individuals,” Dudley Lamming, PhD, one of the review’s authors, said in a press release. “But because most people are relatively sedentary, many people are likely consuming more protein than they actually need, which probably has negative health consequences.”

Could eating less protein extend your life span? 

The review found that moderate protein restriction — and restricting specific amino acids, including methionine, isoleucine, and valine — extended life span in rodent studies.

For example, one study found that valine restriction increased life span by 23% in middle-aged male mice.

Short-term clinical trials linked protein restriction to improved blood sugar and reduced fat mass, but researchers found no direct evidence that it extends life span in people.

“I found the results of this study surprising. Currently, [the] most effective diets emphasize protein while reducing carbohydrates and sugars,” said Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA.

Current Dietary Guidelines for Americans recommend consuming 1.2 to 1.6 grams of protein per kilogram of body weight daily for adults — up to twice the minimum recommended amount of 0.8 grams per kilogram.

Taken together, the findings suggest there is no one-size-fits-all approach to protein intake.

How protein restriction may support healthy aging

The review also examined specific amino acids, the building blocks of protein. Researchers found that higher intake of methionine, isoleucine, and valine may activate biological pathways involved in growth.

When these pathways remain overly active, they may increase the risk of inflammation, obesity, and other conditions associated with aging.

Protein restriction may also trigger several metabolic changes believed to support healthy aging.

According to the animal studies reviewed, it can raise FGF21 levels, which may boost metabolism and reduce inflammation. In mice, higher FGF21 levels were also associated with longer life span, with female mice living about 40% longer and males about 30% longer.

Protein restriction may also alter the signaling pathways of the nutrient sensors mTORC2 and GCN2, promoting autophagy, the body’s natural process of removing damaged cellular components and replacing them with healthier ones.

Researchers also found that protein restriction may improve mitochondrial function, reducing oxidative stress and enhancing energy production. It may also help preserve youthful gene expression patterns.

Although the findings are promising, it’s important to note that most of the evidence comes from animal studies, and longer-term research in humans is still needed.

Why reducing protein may not be right for everyone

While reducing protein intake may benefit some people, higher protein intake remains important for others.

Older adults are among the groups most likely to benefit from eating more protein. They generally need 1.0-1.2 grams of protein per kilogram of body weight daily. For those with sarcopenia or certain chronic diseases, protein needs may increase to 1.5-2.0 grams per kilogram.

Other groups who may require more protein include:

• pregnant people
• children
• adolescents
• athletes
• people recovering from illness or injury

Because protein needs vary by age, activity level, and overall health, it’s important to speak with a healthcare professional or registered dietitian before making major dietary changes.