The roughly one year signal appeared only in men, and the study measured blood tyrosine rather than supplement intake, so the gap between the finding and the headline is exactly what readers should learn to see.
A new study published in Aging-US links higher blood levels of tyrosine, an amino acid common in meat, eggs, and dairy and widely sold in focus and brain-health supplements, to shorter lifespans in men. The signal is real and large enough to be worth reading carefully. It is also narrower, and easier to misread, than the headlines will suggest, because the study measured tyrosine in the blood, not the tyrosine someone swallowed in a pill.
The analysis drew on data from more than 270,000 people enrolled in the UK Biobank and was reported on June 15, 2026, in Aging-US, a peer-reviewed journal published by Impact Journals LLC. The research was conducted by Jie V. Zhao, Yitang Sun, Junmeng Zhang, and Kaixiong Ye of the University of Hong Kong and the University of Georgia. Among men, those with higher tyrosine levels consistently lived shorter lives, with an estimated lifespan loss on the order of roughly one year. Phenylalanine, the other amino acid the researchers tracked, did not produce the same pattern after controlling for tyrosine. The lifespan signal appeared in men. The source summary did not highlight a comparable signal in women.
The headline version of this story, that a popular brain supplement shortens lives, is not the same as what the study actually measured. Blood tyrosine is shaped by dietary protein, individual metabolism, and the body's own production of the amino acid from phenylalanine. It is not a clean proxy for supplement intake. The study did not directly examine tyrosine supplements or test whether taking supplemental tyrosine shortens lifespan. Until the primary paper clarifies how exposure was defined, treating this as a verdict on brain supplements is a category error.
A few design features are worth keeping in mind. The study is observational, which means it tracks associations in a population rather than running a controlled experiment. The researchers also used Mendelian randomization, a genetic method that helps distinguish causation from coincidence, but even this technique cannot fully eliminate confounding in an observational framework. An association of roughly a year in a single cohort can shrink, disappear, or change sign when the same data are reanalyzed or when the model is adjusted for different covariates. The sex-specific signal is the part of this study that does real scientific work, because it narrows the question to a biological mechanism worth investigating, rather than serving as a universal warning.
The transferable lesson is how to read the next study that lands in your feed with this shape. Ask what was actually measured, and whether that matches what the headline is talking about. Ask whether the signal is isolated to one subgroup, and whether that subgroup makes biological sense. Ask what would have to be true for the headline to be right, and whether any of that is in the data. None of this is a substitute for reading the paper, but it will keep a reader from being whiplashed by the next "this thing is secretly killing you" headline.
The honest summary: a 270,000-person dataset from the UK Biobank, peer-reviewed in Aging-US, found a roughly one-year association between higher blood tyrosine and shorter lifespan in men, and did not show the same thing in women. That is a piece of evidence worth noting, not a rule to live by. The watch item, as the field digests the paper, is whether the exposure definition, the covariates, and the sex-specific effect hold up in independent cohorts, and whether a dose-response curve ever emerges. If it does, the supplement question becomes answerable. Until then, the strongest claim a reader can make is that this is a study to watch, not a brain supplement to throw out.