A common amino acid found in protein-rich foods and many brain health supplements may have an unexpected connection to longevity, according to new research.
Scientists report in the magazine. Aging-USA examined whether two amino acids, phenylalanine and tyrosine, could influence how long people live. Their findings suggest that higher blood levels of tyrosine are associated with shorter life expectancy in men, raising new questions about the role this nutrient may play in aging.
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.
What are phenylalanine and tyrosine?
Amino acids are often described as the building blocks of proteins. The body uses them to create and repair tissues, produce enzymes, and support countless biological functions.
Phenylalanine and tyrosine are two amino acids that help regulate metabolism and brain activity. They are naturally present in many foods, particularly meat, fish, eggs, dairy products and other protein-rich sources. They are also available in dietary supplements marketed for energy, focus, and cognitive performance.
Tyrosine is especially notable because it helps the body produce neurotransmitters such as dopamine, norepinephrine, and epinephrine. These chemical messengers play important roles in mood, attention, motivation, memory, and the body’s response to stress.
Because of these functions, tyrosine has attracted increasing interest among researchers studying aging, brain health, and life expectancy.
Study analyzed more than 270,000 people
To investigate whether these amino acids affect longevity, researchers analyzed genetic and health information from more than 270,000 participants enrolled in the UK Biobank, one of the largest long-term health databases in the world.
The team used two complementary approaches. First, they examined the observed relationships between amino acid levels and mortality. They also used a technique called Mendelian randomization, a genetic method that helps scientists determine whether an observed association may reflect a cause-and-effect relationship rather than simple coincidence.
This combination allowed the researchers to look beyond the correlations and obtain stronger evidence on whether amino acid levels could directly influence lifespan.
Tyrosine highlighted as a potential risk to longevity
At first glance, both phenylalanine and tyrosine seemed to be associated with an increased risk of death. However, after taking into account additional factors and performing more detailed analyses, only tyrosine continued to show a consistent relationship with life expectancy.
The findings suggested that higher levels of tyrosine may contribute to shorter life expectancy in men.
Based on genetic analysis, the researchers estimated that elevated levels of tyrosine could shorten men’s life expectancy by almost a year.
Women did not show the same pattern. The study found no significant association between tyrosine levels and life expectancy among participating women.
The researchers also noted that men generally have higher tyrosine levels than women, which may help explain some of the long-observed difference in average life expectancy between the sexes.
“Phenylalanine showed no association with life expectancy in either men or women after controlling for tyrosine.”
Why might tyrosine affect aging?
Scientists still don’t know exactly how tyrosine might influence lifespan, but several possibilities have emerged.
One possible explanation has to do with insulin resistance, a condition in which the body’s cells respond less to insulin. Insulin resistance is linked to numerous age-related health problems, including type 2 diabetes, cardiovascular disease, and metabolic disorders.
Tyrosine can also affect the production of neurotransmitters involved in the body’s response to stress. Over time, alterations in these systems could potentially influence long-term health and aging.
Researchers suspect that hormone-related pathways may also play a role. Because these biological pathways may function differently in men and women, they may help explain why the apparent lifespan effect was observed only in men.
What does this mean for supplements?
Tyrosine is often marketed as a supplement that can help support concentration, mental performance, and alertness, especially during stressful situations.
However, the new findings suggest there may be more to the story when considering long-term health.
Importantly, the researchers did not directly examine tyrosine supplements or test whether taking tyrosine supplements shortens lifespan. Instead, the study focused on natural blood levels of the amino acid and how those levels were associated with longevity.
As a result, the findings should not be interpreted as evidence that tyrosine supplements are harmful. However, they do suggest that elevated tyrosine levels might be worth investigating further.
Researchers note that dietary strategies, such as reducing total protein intake, may help reduce tyrosine levels. Future studies will be needed to determine whether these approaches can safely improve healthy aging and life expectancy.
More research is needed
While the study provides some of the strongest evidence yet linking tyrosine to longevity, many questions remain unanswered.
Scientists will need to confirm the findings in additional populations and better understand the biological mechanisms involved. Researchers also hope to learn whether diet, lifestyle changes or other interventions can safely reduce tyrosine levels and potentially promote healthier aging.
For now, the study highlights an intriguing possibility: A nutrient best known for supporting brain chemistry may also have an unexpected connection to how long people live.