Popular brain supplement linked to shorter lifespan in men — SkimNews
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- Jie V. Zhao and colleagues analyzed more than 270,000 UK Biobank participants, combining blood-amino-acid measurements, death outcomes, predicted lifespan and Mendelian randomization to examine phenylalanine and tyrosine.
- The initial analyses associated higher phenylalanine and tyrosine with increased death risk, but after controlling for tyrosine, phenylalanine showed no lifespan association in either sex.
- The genetic analysis estimated that elevated tyrosine could correspond to nearly one year less life expectancy in men, while no significant effect appeared in women.
- The tyrosine finding remained after researchers accounted for phenylalanine and related factors; men also generally had higher tyrosine levels than women.
- The study did not directly test tyrosine supplements, measuring blood concentrations instead; the findings therefore do not show that taking a tyrosine supplement shortens lifespan.
- The researchers proposed insulin resistance and sex differences in stress-response signaling as possible mechanisms, while neither those mechanisms nor deliberately lowering protein intake has been established as a longevity strategy.
Why it matters: For supplement users and clinicians, the decisive distinction is that the 270,000-plus-person UK Biobank study examined blood tyrosine—not tyrosine pills. Its male lifespan association does not justify protein restriction, and the researchers say more study is needed before health recommendations.
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