A widely used nutrient in cognitive supplements may carry an unexpected cost for men, according to new research published in the journal Aging-US. Scientists analyzing data from over 270,000 people found that higher blood levels of tyrosine, a common amino acid, were consistently linked to shorter lifespans in men.
Tyrosine is one of two amino acids researchers examined for their potential connection to longevity. The compound occurs naturally in protein-rich foods including meat, fish, eggs, and dairy products, and is also sold as a standalone supplement marketed to enhance focus, energy, and mental performance. The nutrient plays a key role in producing dopamine and other brain chemicals involved in mood, attention, and stress response.
Researchers from the University of Hong Kong and University of Georgia analyzed health information from participants in the UK Biobank, one of the world's largest long-term health databases. They employed two distinct analytical methods: examining direct associations between amino acid levels and mortality, and using genetic analysis to probe whether observed connections might reflect actual cause-and-effect relationships rather than coincidence.
The results pointed specifically to tyrosine. While both tyrosine and its related amino acid phenylalanine initially appeared linked to higher death risk, only tyrosine maintained a consistent relationship with lifespan after detailed statistical adjustments. Genetic analysis suggested elevated tyrosine levels could reduce men's lifespan by nearly one year.
The effect was notably absent in women. Female study participants showed no significant association between tyrosine levels and life expectancy, even though men generally maintain higher tyrosine concentrations in their blood. Researchers speculated this sex-based difference might help explain documented differences in average lifespan between men and women.
The mechanism behind tyrosine's apparent connection to longevity remains unclear. Scientists point to several possibilities: the amino acid may influence insulin resistance, a risk factor for diabetes and cardiovascular disease; it could disrupt neurotransmitter pathways involved in stress response; or hormone-related biological systems that function differently in men versus women may be at play.
An important limitation deserves emphasis: the research did not test whether taking tyrosine supplements actually shortens lifespan. Instead, scientists measured naturally occurring blood levels and their associations with mortality. The distinction matters significantly because supplement effects may differ from the impact of elevated baseline levels occurring through diet alone.
Tyrosine supplements remain popular among people seeking cognitive enhancement and stress management support. Yet the new findings raise questions about long-term safety that extend beyond the immediate cognitive benefits marketers emphasize. Researchers suggest that dietary approaches, such as moderating overall protein consumption, might lower tyrosine levels, though no interventions have yet been tested for safety or efficacy in improving healthy aging.
The research team plans further investigation to confirm findings in other populations and understand the biological pathways involved. Studies exploring whether lifestyle changes can safely reduce tyrosine levels and support longer, healthier lives are next on the agenda.
Author Jessica Williams: "A supplement taken daily by millions for brain boost might carry a hidden cost for men, and nobody's really studied whether cutting it out makes a difference yet."
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