A tyrosine lifespan study in men involving more than 270,000 participants has found that higher blood levels of the amino acid tyrosine are associated with a shorter life expectancy in men, while no equivalent effect was observed in women. The research, published in Aging-US and subsequently covered by the University of Georgia Department of Genetics, used both observational data and genetic analysis in an attempt to test whether the relationship might go beyond a simple correlation.
Tyrosine is an amino acid the body produces from phenylalanine and obtains from protein-rich foods. It is also widely sold as a dietary supplement, commonly marketed for improving focus, alertness, and mental performance. The fact that the study concerns an ingredient with a sizable commercial supplement market is, on its own, a reason to read the methodology carefully before drawing conclusions.
What the tyrosine lifespan study in men actually found
The researchers, led by Jie V. Zhao, Yitang Sun, Junmeng Zhang, and Kaixiong Ye from the University of Hong Kong and the University of Georgia, drew on data from the UK Biobank, a large research database containing health and genetic information from people in the United Kingdom. They examined whether blood concentrations of phenylalanine and tyrosine were associated with mortality outcomes and predicted lifespan.
Initially, higher levels of both amino acids appeared linked to an increased risk of death. On closer inspection, tyrosine was the one that consistently stood out. Phenylalanine, the researchers state, showed no association with lifespan in either men or women once tyrosine was accounted for.
The team then applied Mendelian randomisation, a method that uses naturally occurring genetic variants as a proxy for exposure to a biological factor. Because genetic variants are assigned before lifestyle choices and most diseases develop, the technique can sometimes provide stronger evidence of a potential causal link than observational data alone. The genetic analyses suggested that elevated tyrosine levels may have a potentially causal relationship with reduced male life expectancy. Medical Daily reports that the estimated reduction was approximately 0.91 years in men, based on the paper’s genetic modelling.
The researchers also found that men generally carry higher circulating tyrosine levels than women, a difference they suggest could potentially contribute to the well-documented gap in average lifespan between the sexes. They are careful, however, not to assert that tyrosine is responsible for that gap.
Proposed mechanisms remain speculative
The study does not establish why higher tyrosine might be associated with shorter male lifespans. Two candidate mechanisms are discussed. One involves insulin resistance: when cells become less responsive to insulin, the hormone that helps regulate blood sugar, the resulting metabolic disruption is associated with several age-related diseases. The other involves tyrosine’s role in producing neurotransmitters linked to the stress response, pathways that can function differently in men and women. Both remain hypotheses requiring further investigation; the paper itself does not claim to have settled the question.
There is also a broader complication. The study examined tyrosine levels in the body and their relationship with longevity. It did not directly test tyrosine supplements. The researchers are explicit on this point: the results do not show that taking a supplement shortens lifespan. Chronically elevated blood tyrosine from any source, diet included, is what the analysis concerns. The researchers suggest that people with unusually high tyrosine concentrations might consider dietary changes to lower those levels, noting that restricting protein intake is one possible avenue. Whether deliberately reducing tyrosine through diet would actually extend lifespan remains, in their own framing, unclear.
Questions the study leaves open
The sex-specific finding is the aspect most likely to be overstated in wider coverage. The researchers themselves frame it as a clue to understanding why ageing and longevity differ between the sexes, not as a ready explanation. The gap between a Mendelian randomisation signal in a cohort study and a usable health recommendation is considerable, and the authors are careful to say more research is needed before the results can inform clinical advice.
What the study does establish, with reasonable confidence, is that tyrosine merits further investigation as a factor in male longevity. The 0.91-year estimate is a modelled figure derived from genetic proxies, not a direct measurement, and should be interpreted as a statistical estimate rather than a precise forecast. With that caveat noted, a dataset of more than 270,000 participants and a methodology that attempts to address confounding gives the finding more traction than a smaller observational study would. The next step, as the researchers acknowledge, is replication and a clearer account of the biological pathway involved.
