A common ingredient found in brain health supplements may carry an unexpected risk for men, according to new research published in the journal Aging-US.
Scientists from the University of Hong Kong and the University of Georgia examined whether two amino acids, phenylalanine and tyrosine, could influence how long people live. Their findings, reported by Science Daily, suggest that higher levels of tyrosine in the blood are associated with shorter life expectancy in men, potentially by close to a year.
The research team included Jie V. Zhao, Yitang Sun, Junmeng Zhang, and Kaixiong Ye. They drew on health and genetic data from more than 270,000 participants enrolled in the UK Biobank, one of the largest long-term health databases in the world.
Tyrosine is an amino acid naturally present in meat, fish, eggs, dairy products, and other protein-rich foods. It helps the body produce neurotransmitters including dopamine, norepinephrine, and epinephrine. Those chemical messengers play roles in mood, attention, motivation, memory, and the body's response to stress. Because of those functions, tyrosine has become a popular ingredient in supplements marketed for focus, energy, and cognitive performance.
The researchers used two methods to study the connection between amino acid levels and mortality. First, they examined observed relationships between blood amino acid levels and death rates. Second, they applied a technique called Mendelian randomization, a genetic method that helps scientists assess whether an association may reflect a cause-and-effect relationship rather than coincidence.
That combination of approaches allowed the team to look beyond simple correlation and build a stronger case that amino acid levels might directly affect lifespan.
Tyrosine was the standout finding. While phenylalanine was also examined, it was tyrosine that showed the consistent link to shorter lifespans, specifically in men. The association was not found in the same way across all participants, pointing to a sex-specific effect that researchers say warrants further investigation.
The findings raise new questions about tyrosine's role in aging, particularly given how widely the amino acid is promoted and consumed as part of daily supplement routines aimed at brain performance.
