Study links tyrosine to shorter lifespan in men

Earth.com on May 22 pointed to a 2025 paper in the journal Aging that linked higher tyrosine levels to shorter lifespan in men, a finding drawn from UK Biobank data and genetic analysis rather than a trial of supplements. Tyrosine is an amino acid found in protein-rich foods and in products marketed for focus and stress tolerance. The study did not test whether taking a tyrosine pill causes harm. It examined whether people with higher measured or genetically predicted tyrosine levels tended to have shorter lifespans. ### What exactly did the study find? The Aging paper reported that tyrosine, but not phenylalanine after adjustment, was associated with shorter lifespan in men. In multivariable Mendelian randomization, the authors estimated that higher tyrosine levels were linked to about 0.91 fewer years of life in men, with no clear association in women. More than 272,000 UK Biobank participants were included in the analysis, according to Earth.com’s summary of the paper, while other coverage of the same study described the sample as more than 270,000 people. (earth.com) The authors were Jie V. Zhao and Junmeng Zhang of the University of Hong Kong, and Yitang Sun and Kaixiong Ye of the University of Georgia. ### Did the researchers study supplements directly? (aging-us.com) HealthDay reported on February 27 that the study did not test tyrosine supplements directly. That distinction matters because blood levels of an amino acid can reflect diet, metabolism, illness, body composition or other biological factors, not just supplement use. ScienceDaily, citing the paper and a release from the journal’s publisher, said the researchers combined observational analysis with Mendelian randomization, a method that uses genetic variants associated with a trait to test whether the relationship may be causal. (earth.com) The paper said the team used genetic variants associated with phenylalanine and tyrosine in UK Biobank and applied them to lifespan genome-wide association studies, including parental, paternal and maternal attained ages. (usnews.com) ### Why are researchers focused on tyrosine in the first place? Tyrosine is involved in metabolism and helps produce neurotransmitters including dopamine, adrenaline and noradrenaline, which is one reason it appears in products sold for mental performance. Phenylalanine, a related amino acid, is its precursor. The paper examined both because the two are biologically linked and can be hard to separate analytically. (sciencedaily.com) Earth.com said the study discussed two possible pathways behind the association: insulin resistance and stress-related neurochemistry. HealthDay reported that researchers said men tend to have higher tyrosine levels than women, which they said could help explain the sex-specific result, though the mechanism remains unresolved. ### How strong is the evidence? (earth.com) The paper’s own conclusion was narrower than some headlines. The authors wrote that reducing tyrosine in people with elevated concentrations “may” help prolong lifespan and said sex-specific pathways should be explored further. That leaves the finding as an association supported by genetic inference, not a clinical recommendation to stop eating protein-rich foods or abandon supplements across the board. Josh Bloom of the American Council on Science and Health wrote on May 19 that elevated tyrosine could be a marker of poorer metabolic health rather than a direct cause of aging. That is an outside interpretation, not a finding from the paper itself, but it reflects the main caution in reading nutrition-linked longevity research. ### Where can readers check the source paper? (aging-us.com) The paper, “The role of phenylalanine and tyrosine in longevity: a cohort and Mendelian randomization study,” was published in Aging on October 3, 2025. The journal page lists Jie V. Zhao as corresponding author and includes the full text and figures describing the observational and sex-specific genetic analyses. (pdfs.semanticscholar.org) (acsh.org)