Study links high tyrosine levels to shorter lifespan in men

Researchers from the University of Hong Kong and the University of Georgia investigated whether phenylalanine and tyrosine, two amino acids involved in metabolism and brain function, are connected to human lifespan. The study, published in the journal Aging-US, analyzed data from more than 270,000 participants in the UK Biobank.

A sex-specific difference

Initially, higher levels of both amino acids appeared linked to increased risk of death, but closer analysis showed that only tyrosine had a consistent association. Genetic analyses, including a method called Mendelian randomization, suggested that elevated tyrosine may have a causal relationship with reduced life expectancy in men — with estimates pointing to a shortening of nearly one year. No significant effect was found in women. The link persisted even after accounting for phenylalanine and other factors, while phenylalanine itself showed no association with lifespan.

The researchers also found that men generally have higher tyrosine levels than women, which could partly contribute to the well-known lifespan gap between the sexes, though the study does not prove tyrosine is responsible for that gap.

Possible mechanisms and caution

Scientists propose several unconfirmed explanations, including a possible link to insulin resistance and tyrosine's role in producing stress-related hormones, which may function differently in men and women. The researchers emphasize that they did not directly test tyrosine supplements, so the findings do not show that taking such supplements shortens lifespan. Further research is needed to determine whether dietary changes, such as reducing protein intake, could safely lower tyrosine levels and support healthier aging.