This Popular Supplement Ingredient May Be Cutting Men’s Lives Short

The label promises sharper focus, steadier nerves and a better response to pressure. Few shoppers stop to ask what the same ingredient might mean over decades. A team of researchers did, pulling health and genetic records from more than 270,000 people in the UK Biobank and comparing two closely related nutrients against how long participants lived. One of the two kept surfacing in the data, and the pattern was clearest in men.

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Tyrosine, Found in Cheese, Soy and Beef, Is Marketed as a Brain and Stress Aid

The ingredient is tyrosine, an amino acid present in cheese, soybeans, beef, and other protein-rich foods. The body uses it to build dopamine and norepinephrine, chemicals tied to mood, attention, and the stress response. Supplement makers sell it for focus, and a research review found it can sharpen thinking during short bursts of stress or mental strain. Those studies followed performance for hours. Far less is known about what high tyrosine levels mean over decades.

Mendelian Randomization Uses Genes Fixed at Birth to Probe Cause and Effect in Lifespan

Blood tests alone can mislead, because diet, habits and health problems all shape amino acid levels. To get around that, the team added Mendelian randomization, a method that uses gene variants people are born with to test whether a link reflects cause and effect. Daily choices cannot sway those genes. The study, published in Aging-US, set the observed patterns against the genetic evidence. The first results made both nutrients look like trouble.

Phenylalanine and Tyrosine Both Appear Tied to Higher Death Risk in Early Analysis

In the first pass, higher blood levels of both phenylalanine and tyrosine tracked with a greater risk of death. The two are chemical relatives, since the body makes tyrosine from phenylalanine, so their levels rise and fall together and are hard to separate. Researchers needed to know whether both mattered or whether one was simply riding along with the other. They adjusted each for the influence of the other, and the results split apart.

Phenylalanine Drops Out While Tyrosine Stays Linked to Shorter Lifespan After Adjustment

Once tyrosine was taken into account, phenylalanine showed no link to lifespan in men or women. Tyrosine held its ground. That result led the authors to suggest that tyrosine may influence aging independently. Their own conclusion is cautious: lowering tyrosine in people with elevated levels may help extend life. The genetic estimates also attached a figure to the effect, and it was measured in years.

Genetic Estimates Put Cost of High Tyrosine for Men at Nearly One Year of Life

For men with higher tyrosine, the estimates pointed to a lifespan shortened by nearly one year. For scale, American men lived 76.5 years on average in 2024 and women 81.4, according to CDC figures reported by Healio. Researchers noted that men tend to carry higher tyrosine levels than women, which may help explain part of that difference. Women’s results were harder to read.

Results for Women Prove Less Consistent Than Early Headlines Suggested

In the observational analysis, higher tyrosine tracked with greater death risk in men but not women, though the difference between the sexes did not reach statistical significance. In the genetic analysis, higher tyrosine predicted shorter lifespan in both sexes at first, while women’s findings varied across methods once phenylalanine was controlled for. The male pattern is stronger, and researchers have floated explanations for it. Hormones are among the suspects.

Insulin Resistance and Hormones Top List of Possible Explanations for Male Pattern

The authors did not settle on a single cause. One possibility is insulin resistance, a state in which cells respond poorly to insulin, which feeds into type 2 diabetes, heart disease and other age-related problems. Tyrosine may also interact with hormones such as testosterone, which could explain why men show the stronger pattern. Its role in making stress chemicals offers a third route. Each idea remains a hypothesis, and none answers the question supplement users care about most.

Authors Say Findings Do Not Show Tyrosine Supplements Shorten Life

The researchers measured tyrosine that occurs naturally in the blood. They never tested supplements or checked whether taking them changes lifespan, and they say the results do not show that tyrosine-rich foods or supplements shorten life. The genetic data also overlaps with the same UK Biobank population, a setup that can introduce bias. One idea for lowering tyrosine levels did emerge from the work, and it comes with a catch.

Large Genetic Study Singles Out Tyrosine as a Marker Worth Watching in Men

Of two related amino acids, only tyrosine stayed linked to shorter lifespan once the data was sorted, with the clearest signal in men and an estimated cost of nearly one year. Cutting overall protein could lower tyrosine, though whether that supports healthy aging is unknown. Supplements were never part of the experiment, so the result describes a pattern in blood chemistry and carries no verdict on capsules or powders. Anyone taking tyrosine long term has reason to raise it with a doctor.