An amino acid found in meat, fish and energy drinks might be a key regulator of aging in animals, a new study suggests.
However, experts warn that no one should start seeing Red Bull as a fountain of youth.
Editor's Note: New Aging Research Reveals Key to Long, Healthy Life
Researchers found that deficiencies in the amino acid, called taurine, seemed to be a prime driver of aging in lab mice: Their taurine levels naturally declined with age, but giving middle-aged mice a daily taurine supplement for one year essentially slowed the aging process.
Compared with lab mice fed a placebo supplement, the taurine-consuming mice survived 10% to 12% longer.
These mice were also more likely to be living their best lab-mouse lives — staying leaner, maintaining stronger bones and muscles, showing fewer depression- and anxiety-like behaviors, and holding on to a "younger-looking" immune system.
"Whatever we checked, taurine-supplemented mice were healthier and appeared younger than the control mice," said study leader Vijay Yadav, an assistant professor of genetics and development at Columbia University, in New York City.
When the scientists repeated the supplement experiment in middle-aged monkeys, they observed similar effects.
One major caution, the researchers and other experts said, is that mice and monkeys, studied in a controlled lab setting, are not people living their complicated lives out in the world.
And the research offers no proof that taurine supplements can help humans live longer and healthier.
"We do not recommend that people go out and buy taurine off the shelf," Yadav said.
Instead, he and his colleagues think taurine supplements should be put to the test in a clinical trial.
What that trial would look like is unclear, said study co-author Henning Wackerhage, a professor at Technical University of Munich, in Germany.
But broadly, it could mean having middle-aged adults take taurine or a placebo every day, then following them over time to see if there are health differences between the two groups.
Taurine is an amino acid that the human body synthesizes naturally, and it is also attained from food. Shellfish offer the biggest dose, Yadav said, but taurine is also found in beef and poultry (especially dark meat) and in small amounts in dairy products.
Amino acids are typically "building blocks" that form proteins. But taurine is different, Wackerhage said: It's a free-form molecule that does not get incorporated into proteins. Research has suggested that taurine plays a role in the function of the central nervous system and immune system, and has anti-inflammatory and anti-oxidant properties.
In people, it has not been clear whether the amino acid helps drive the aging process or "just goes along for the ride," Yadav said.
In the new study, published June 8 in the journal Science, the researchers tested taurine supplements in lab animals only.
But they did look at some human data, too. They found that among roughly 12,000 older adults in a European health study, those with higher taurine levels were less likely to have obesity or type 2 diabetes.
That, however, only shows a correlation — not cause and effect, said Joseph Baur, a professor at the University of Pennsylvania Perelman School of Medicine, in Philadelphia.
It could be that some human diseases drive down taurine levels, said Baur, who wrote a commentary published with the study.
But, he added, that chicken-egg problem is why the animal experiments were so crucial. "They show for the first time that increasing taurine can be a driver of increased longevity," Baur noted.
Still, that's an important research step — not lifestyle advice. For the average person today, Baur said, a healthy diet, exercise and not smoking should be the "foundation" of any healthy-aging strategy.
"New ideas, like taurine supplementation, should always be approached with caution and studied in controlled clinical trials," Baur said. "It's much easier to screw things up than to make them better, even with molecules that seem likely to be safe."
Another researcher who was not involved in the study said the findings are scientifically interesting, but worried about how the supplement industry will spin things.
"They can start promoting this as an anti-aging supplement tomorrow," said Dr. Pieter Cohen, an associate professor at Harvard Medical School who studies the content and quality of commercial dietary supplements.
Cohen noted that in the United States, supplements are not subject to the same regulations that medications are. That means they do not have to be proven effective before they are marketed, and consumers cannot be sure any supplement actually contains what's on the label.
Yadav stressed that while taurine is in meat, diets heavy in meat have been tied to ill health effects. And, he said, that's not what his team studied. Nor did they study energy drinks, which would contain lots of other things, like caffeine and sugar.
In yet another portion of the study, the researchers had a group of athletes and couch potatoes pedal away on exercise bikes to the point of exhaustion. Afterward, most showed an increased taurine level in the blood. But it's not clear, the experts said, whether regular exercise actually boosts the body's production of taurine, or whether taurine might be one reason that exercise is good for us.
The researchers acknowledged that the range of benefits seen in the animal experiments "seem too good to be true."
"My take," Wackerhage said, "is that taurine seems to hit the engine room of aging."
Cohen had a more guarded take. With something as complicated as human aging, he said, it would be surprising if one amino acid wielded such power.
The study was funded by government and foundation grants, and had no supplement industry involvement, the researchers said.