A new study is challenging one of the most widespread assumptions in modern nutrition, suggesting that consuming less protein rather than more may promote healthier ageing and reduce the risk of several chronic diseases.
The findings are based on the review The Hallmarks of Protein and Amino Acid Restriction in Aging and Longevity by Bailey A. Knopf and Dudley W. Lamming, published in Cell Press Blue. The researchers reviewed more than 350 studies examining the links between protein intake, metabolism, healthspan and longevity.
At a time when "proteinmaxxing", a trend promoting increased protein consumption through supplements and protein-enriched foods, has become increasingly popular, the researchers argue that lower protein intake may offer important health benefits.
Researchers at the University of Wisconsin-Madison concluded that, despite longstanding recommendations favouring higher protein consumption, emerging evidence suggests that reduced protein intake may help lower the incidence of age-related conditions such as diabetes and cancer.
As populations age worldwide, scientists are placing increasing emphasis on identifying dietary interventions capable of extending healthy lifespan and reducing the burden of chronic disease.
Study author Dudley Lamming said the benefits of protein for muscle growth and exercise performance are well established, particularly among physically active individuals.
However, he noted that many people lead relatively sedentary lifestyles and may be consuming more protein than they actually need, potentially creating negative health consequences.
Metabolic benefits
According to the researchers, reducing protein intake may improve metabolic health by:
- Reducing body fat.
- Increasing energy expenditure.
- Improving blood sugar regulation.
Both animal and human research reviewed in the study found that lower-protein diets were associated with better blood glucose control and reduced body fat, even when total calorie consumption increased.
A key mechanism appears to involve FGF21, a hormone that rises when protein intake falls and helps the body use energy more efficiently.
Triggering the body's repair mechanisms
The review also found that lower protein intake may encourage the body to enter a maintenance process known as autophagy.
Autophagy enables cells to break down and remove damaged proteins and other cellular waste, helping to preserve normal cell function and potentially slowing aspects of the ageing process.
By strengthening this natural cellular repair system, protein restriction could contribute to healthier ageing and improved longevity, according to the researchers.
Not suitable for everyone
The researchers stressed that protein restriction is not appropriate for all groups.
People who may require higher protein intake include:
- Pregnant women.
- Children and adolescents.
- Older adults.
- People recovering from major injuries or illness.
For these groups, adequate protein remains essential for growth, recovery and the maintenance of muscle mass.
How much protein is recommended?
The European Food Safety Authority (EFSA) and the World Health Organization (WHO) recommend a daily protein intake of 0.83 grams per kilogram of body weight for adults.
Both organisations state that consumption of up to twice that level is generally considered safe, while evidence regarding the long-term effects of very high protein intake remains debated.
EFSA also notes that there is insufficient evidence to establish separate protein requirements for older adults and recommends that they consume at least as much protein as younger adults.
A personalised approach
Lamming noted that public health recommendations have encouraged both higher protein intake and increased physical activity.
He argued that future dietary guidance should be tailored not only to age but also to an individual's level of physical activity, overall health and lifestyle.
The researchers concluded that while many people may consume substantially more protein than necessary and could potentially benefit from lowering their intake, dietary advice should ultimately be personalised to reflect individual circumstances and health needs.
Source: Euronews
