Low-protein, methionine-rich diet may unlock healthier ageing, study reveals

A new study suggests that a carefully designed low-protein diet with added methionine could extend healthspan in ageing organisms. The research, published in Cell Metabolism, involved scientists from USC, the University of Toronto, and Harvard University. Their findings challenge common assumptions about protein intake and metabolic health. The team examined four different diets in mice: a standard diet, a Western-style diet, a ketogenic diet, and a novel low-protein methionine-supplemented longevity diet (LDMM). Despite consuming the same number of calories as the other groups, mice on the LDMM diet showed reduced fat mass, improved mobility, and greater strength. They also exhibited lower frailty and a longer healthspan.

Blood tests revealed higher levels of growth hormone, GLP-1, and FGF21 in the LDMM group. These hormones are linked to better metabolic function. Human data further supported the findings—high animal protein intake, which increases methionine, raised the risk of obesity and Type 2 diabetes.

In contrast, plant-focused diets with controlled amino acid intake correlated with fewer metabolic diseases. The researchers developed the LDMM diet based on traditional Mediterranean eating patterns, fine-tuning methionine levels for optimal health benefits. The study combines mouse experiments and human data to highlight the potential of a methionine-calibrated, low-protein diet. This approach may reduce fat accumulation, improve mobility, and lower disease risk without cutting calories. The findings point to dietary adjustments that could support healthier ageing.