A review of studies in rodents suggests that restricting protein intake may slow ageing, though experts caution that these findings may not directly translate to human health.
Key facts
- •Rodents fed the minimum recommended protein intake lived over 50 percent longer in one study compared to those fed double that amount.
- •US dietary guidelines currently recommend 1.2 to 1.6 grams of protein per kilogram of body weight for optimal health.
- •The minimum protein requirement to prevent deficiency is 0.8 grams per kilogram of body weight.
- •Researchers are investigating whether drugs that deplete specific amino acids, such as isoleucine and valine, could improve blood sugar control in humans.
- •Dudley Lamming suggests that regular exercise may mitigate the potential harms of high protein intake by requiring more protein for muscle repair.
A review of over 300 studies, primarily involving sedentary rodents, suggests that limiting protein intake to the minimum required to prevent deficiency may slow ageing and extend lifespan. Dudley Lamming at the University of Wisconsin-Madison notes that excessive protein consumption in sedentary subjects can lead to metabolic issues. However, other researchers emphasize that animal studies do not always mirror human biology, and higher protein intake has been associated with health benefits in people.
By the numbers
Potential Biological Mechanisms
Research indicates that protein restriction may increase levels of the hormone FGF21, which can improve blood sugar levels and reduce the accumulation of senescent cells that cause inflammation. Additionally, limiting protein intake has been shown to dampen the activity of the protein mTORC1 in mice. This shift encourages cells to prioritize repair over growth, potentially reducing the risk of age-related conditions.
Debate Over Human Application
Experts like Donald Layman of the University of Illinois Urbana-Champaign argue that rodents and humans differ significantly in protein metabolism and lifestyle factors, such as meal frequency and environmental stressors. While some studies suggest high protein intake helps prevent frailty in humans, other researchers note that evidence regarding protein's impact on human ageing remains mixed. Future research, including upcoming studies on amino acid depletion, aims to further clarify these effects.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by New Scientist.
