💊 A popular dietary supplement could shorten men's lives

The influence of dietary compounds on aging is a rapidly growing field of research. Amino acids, the building blocks of proteins, could play a surprising role in lifespan.

A team of researchers from the University of Hong Kong and the University of Georgia examined two particular amino acids: phenylalanine and tyrosine. Their work, published in the journal Aging, explores the potential links between these molecules and human longevity.


To conduct their investigation, the scientists analyzed data from more than 270,000 people enrolled in the UK Biobank. They combined clinical observations with genetic techniques, such as Mendelian randomization (see below), to assess the associations between blood concentrations of these amino acids and mortality. This approach allows for a better understanding of cause-and-effect relationships, using natural genetic variations as indicators.

The results indicate that high concentrations of tyrosine in the blood are correlated with a reduced life expectancy in men. This relationship appears specific to males, as no significant effect was observed in women. According to genetic estimates, men with higher levels of tyrosine could see their lifespan decrease by nearly a year. Phenylalanine, on the other hand, does not show an independent association after adjustment for tyrosine.

The underlying mechanisms could involve insulin resistance and the production of stress-related neurotransmitters. Tyrosine is used by the body to synthesize dopamine and other molecules, which can influence various biological processes differently depending on sex. These hormonal and metabolic pathways would partly explain the differences observed between men and women in aging.

These findings raise questions about the common use of tyrosine in nutritional supplements. Although often promoted to improve concentration and energy, excessive consumption could have long-term consequences on men's health. The researchers note that dietary adjustments, such as protein restriction, could help moderate tyrosine levels and support healthier aging.

Further work is needed to confirm these observations and explore practical strategies. It remains to be determined whether changes in diet or lifestyle can safely lower tyrosine concentrations to promote longevity. This study paves the way for new avenues of research on the interactions between nutrition, metabolism, and sex-specific aging.

Mendelian randomization: a tool for understanding causes

Mendelian randomization is a statistical method that uses natural genetic variations to assess causal relationships between factors and health outcomes. In this study, the researchers used this technique to examine whether tyrosine levels directly influence lifespan. By exploiting genetic data, they were able to minimize biases related to confounding factors, such as dietary choices or lifestyle habits, which strengthens the reliability of the observed associations.

This approach relies on the principle that genes are randomly assigned at conception, which simulates a natural experiment. Scientists identify genetic variants known to affect tyrosine concentrations, then analyze their link with longevity in large populations. This makes it possible to distinguish simple correlations from true causal effects, offering more robust insights than traditional observational studies.

The application of Mendelian randomization in this context revealed a potentially causal link between tyrosine and a reduced life expectancy in men. The results indicate that modifying the levels of this molecule could have an impact on aging, opening perspectives for targeted interventions. This method continues to gain popularity in epidemiological research for exploring the biological determinants of health.