Higher circulating levels of the amino acid tyrosine have been linked to a shorter lifespan in men, according to research analysing more than 270,000 UK Biobank participants.
The study, published in Aging, investigated the relationship between tyrosine, phenylalanine and longevity.
Researchers from the University of Hong Kong and the University of Georgia analysed data from 272,475 participants, including 125,359 men.
Observational analyses found that higher plasma tyrosine was associated with increased all-cause mortality in men — but, interestingly, not in women.
Genetic analysis produced a similar sex-specific signal. After accounting for phenylalanine, genetically predicted higher tyrosine was associated with an estimated 0.91-year reduction in lifespan in men, while the corresponding association in women was not statistically significant.
Phenylalanine itself showed no association with lifespan after adjustment for tyrosine.
Implications for the tyrosine supplement market
The findings could be particularly relevant to manufacturers and brands operating in the cognitive health and nootropic supplement categories.
Tyrosine is a non-essential amino acid found naturally in protein-containing foods and is also marketed as a supplement for cognitive performance, particularly under conditions of stress or high cognitive demand.
Previous research suggests that tyrosine may support aspects of cognition when the brain is under stress or cognitive demands (although evidence of its benefits is inconsistent across populations and conditions).
However, the new longevity findings should not necessarily be interpreted as evidence that tyrosine supplements shorten lifespan — the researchers studied only circulating tyrosine concentrations and genetic proxies rather than conducting a long-term supplementation trial.
The biological mechanism behind the longevity association also remains uncertain.
The researchers highlight possible links to insulin resistance and sex-specific metabolic and hormonal pathways, while noting that residual limitations in the analysis methods mean the findings require further investigation.
For the nutraceutical industry, the research nevertheless highlights a broader challenge: long-term safety and efficacy evidence for ingredients marketed for healthy ageing, cognition and performance.
The authors stated that further studies will be needed to establish whether elevated tyrosine is a genuine modifiable risk factor for longevity or instead a marker of other metabolic processes associated with ageing.
