A brain-boosting nutrient may sharpen your mind but knock years off your life.
Research suggests the popular supplement ingredient, widely touted for improving focus and cognitive performance, may have a surprising downside when it comes to longevity.
Scientists found that men with higher levels of the substance in their blood tended to have shorter lifespans — but women don’t appear to pay the same price.
In the study, scientists from the University of Hong Kong and the University of Georgia analyzed health and genetic information from more than 270,000 people in the UK Biobank.
The researchers were focusing on two amino acids — phenylalanine and tyrosine — and whether they might play a role in aging.
Both are essential building blocks for proteins, but tyrosine also helps the body make dopamine, adrenaline and other brain chemicals involved in mood, focus and stress response.
Phenylalanine, meanwhile, is converted into tyrosine in the body. Both amino acids occur naturally in protein-packed foods and are also commonly found in dietary supplements.
To investigate whether the nutrients play a role in longevity, the researchers first looked at participants’ blood levels and compared them with their mortality and predicted lifespan.
They then used a genetic testing method called Mendelian randomization, which involves looking at natural genetic differences between people to help determine whether one factor might actually cause another.
The team found that men with more tyrosine in their blood appeared to have shorter lifespans — with elevated levels associated with nearly a year shaved off their lives. Women, however, didn’t appear to have the same link.
“Phenylalanine showed no association with lifespan in either men or women after controlling for tyrosine,” the study authors wrote.
Researchers don’t yet fully understand why higher tyrosine levels might be linked to shorter lifespans in men, but they have a few ideas.
One involves insulin resistance, a condition in which the body’s cells become less responsive to insulin, the hormone that helps regulate blood sugar.
Tyrosine plays an important role in the signaling process that allows insulin to tell cells to take up sugar from the bloodstream. While the amino acid is essential for normal cellular function, researchers have suggested that having too much tyrosine circulating in the blood could potentially disrupt that process.
Insulin resistance is associated with a range of health problems that become more common with age — including neurodegenerative diseases, high blood pressure, cardiovascular disease and Type 2 diabetes — all of which can affect longevity.
Tyrosine may also play a role through the brain chemicals it helps produce, which are involved in mood and stress.
The researchers suggested that differences in these chemicals between the sexes could help explain why the link to shorter lifespan appeared in men but not women.
Taking things a step further, they theorized that tyrosine could play some role in the well-documented longevity gap between men and women. However, they stressed that their study doesn’t prove the amino acid is responsible for the difference in average lifespan.
While notable, the findings don’t mean you should dump your supplements down the drain. The researchers didn’t directly test products that contain tyrosine, and there’s no proof that taking them will shorten your life.
After all, other research suggests that tyrosine has real benefits for mental focus, improving memory and boosting cognitive function under stress.
Instead, the study authors suggested that people with unusually high blood concentrations of tyrosine might potentially benefit from dietary changes aimed at lowering those levels.
Tyrosine-rich foods include chicken, turkey, beef, lamb, fish, hard cheeses, eggs, sesame seeds, soybeans and nuts.
