Although ailments multiply in old age, being elderly is not considered a disease. For this reason, it is difficult to propose trials for testing drugs to treat the effects of aging. However, there are several groups of scientists who want to conduct large-scale experiments on humans to see if it is possible to intervene in aging and the health problems associated with it. In the United States, a team led by Nir Barzilai, the director of the Institute for Aging Research at Albert Einstein College of Medicine, is about to begin the Targeting Aging with Metformin (TAME) project, a series of trials involving more than 3,000 participants to test the anti-aging power of metformin, a drug for diabetes. To obtain approval from the Food and Drug Administration (FDA), the agency that approves drugs for sale in the United States, the researchers will analyze metformin’s effects on preventing cardiovascular diseases, cancer and dementia, all of which are more common in old age.
The journal Science just published an international study that proposes including taurine as one of the substances that can slow down aging. This amino acid, famous as an additive in many energy drinks, is found naturally in the body and can be consumed by eating meat, fish or dairy products. In their article, the researchers explain that, in all the animals they studied, they have found that taurine levels in the blood decreased with age. In humans, the team led by Vijay Yadav, of Columbia University, observed that the taurine level in 60-year-olds was only one-third that of five-year-olds. The researcher became interested in taurine during his earlier work on osteoporosis, when he observed its role in bone creation.
The amino acid has also been linked to better functioning of the immune system and less obesity; in addition, it plays an essential role in embryonic development. As the article explains, organisms have up to four times higher concentrations of it in embryonic tissues than in adults; a lack of taurine during an individual’s early development can lead to osteoporosis and blindness, problems that can be alleviated with supplements.
Based on this correlation between taurine deficiency and aging, the researchers tested whether giving taurine as an additive to mice would reduce their biological age. To do so, they chose mice of both sexes aged 14 months, the equivalent of about 45 human years. Every day, some of the mice in the experiment received a taurine pill and others took a placebo. After the experiment, female rodents that had taken taurine lived, on average, 12% longer and male rodents lived 10% longer. That means the mice lived up to four months longer, the equivalent of eight human years. The benefits were not limited to greater longevity; they also had better health and more youthful traits, such as stronger bones and muscles, less depression, less insulin resistance (which is associated with diabetes), less obesity and a stronger immune system.
The hallmarks of aging
In addition to these more visible traits, the study also found that taurine had positive effects on the so-called hallmarks of aging. The pills reduced cellular senescence, the accumulation of cells that are unable to divide and continue to release harmful substances that inflame and injure neighboring cells. In addition, it protected against telomerase deficiency, which can lead to pulmonary fibrosis or dementia; reduced accumulated DNA damage; and alleviated inflammation. Similar beneficial effects were also observed in macaques.
The study also tested exercise’s effect on taurine in both athletes and sedentary individuals. After being subjected to an intense cycling session, taurine levels increased in all individuals but slightly more in sedentary people than in athletes. The authors believe that these results support the idea that taurine and its metabolites at least partially explain the health benefits of exercise and the ways in which it slows down aging. In addition to exercise, the amino acid can be consumed by eating meat or fish but not in a vegan diet.
The authors also studied 12,000 people over the age of 60 and found that higher levels of taurine were associated with less obesity, fewer diagnoses of diabetes, less hypertension and lower levels of inflammation. However, Vijay cautions that these data are a correlation that needs to be tested in randomized trials to show that taurine deficiency causes aging, and that supplementation reverses the process. “We need a randomized placebo-controlled trial to find out if taurine works in humans before suggesting human use of taurine supplements,” Vijay says. “That will take another three to four years,” he estimates.
20 factors that prolong life
Rafael de Cabo, a researcher at the National Institute on Aging in Baltimore, Maryland, recalls that, not so long ago, “the only intervention that served to prolong life in mice was calorie restriction. In recent years, we have seen more than 20 interventions, with molecules such as resveratrol and metformin, that prolong life, something that [once] seemed unthinkable,” he recalls. De Cabo finds the study interesting, although he, like the authors themselves, suggests that a follow-up study is needed to see how taurine levels evolve over time in the same people and what effect it has on certain health markers in order to fully understand the effects of taurine. “In addition, they still need to find the mechanism that explains the relationship between taurine and aging, which they don’t [know now],” he says.
In the meantime, De Cabo recommends using taurine supplements cautiously. “If you look at the EFSA (European Food Safety Authority) data, taurine supplementation is very safe; it’s not a compound we don’t know anything about, but…taking as much as you want without consulting your doctor is not a good idea, particularly for people who have chronic diseases,” the researcher opines. “For example, we don’t know what interactions it may have with other drugs, such as [medication] for diabetes and antidepressants,” he adds. On drinking energy drinks that contain taurine, De Cabo warns that “these drinks have many other substances in addition to taurine. That’s not the way to consume it. We know that a healthy diet and exercise maintain adequate taurine levels. It’s more inconvenient than opening a can, but in the long run it’s better,” he concludes.
Anna Novials, a researcher at the August Pi i Sunyer Biomedical Research Institute (IDIBAPS) believes that the research “is very interesting.” She considers the possibility of proposing studies on the role of taurine in people with diabetes. “It would be one of the mechanisms by which exercise improves metabolic patterns in both healthy individuals and diabetics,” she explains. She doesn’t discard the possibility of researching this amino acid’s effects on combating the diseases associated with aging. However, she warns of the difficulty of conducting the large studies necessary for proving its validity with a natural molecule that would not require a patent. Moreover, there must be long-term studies done to see if taurine can significantly prolong life, as has been seen in mice, or if it turns out that it is not as effective in humans, as has been the case with other substances. Although the data presented in Science are promising, for the moment, there is no guarantee that taurine is the new fountain of youth.
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