Health-conscious people may opt to take a multivitamin, but the jury is out on their benefits
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A daily dose of multivitamins and minerals has already been shown to slightly slow cognitive decline in people over 60. Now, it appears such supplements might also slow ageing more generally.
But this finding relied on an indirect measure of ageing, so it isn’t certain what this means in term of health benefits. We aren’t yet at a point where it could be recommended that all older adults take multivitamins, says Howard Sesso at Harvard University. That said, there may at least be small benefits with very little risk. “There’s been no deleterious effects of a daily multivitamin that we’ve identified so far,” he says.
In the past, it has been claimed that taking individual vitamins can have various benefits, but we now know this can also be harmful. For instance, taking too much vitamin A can weaken bones, excessive vitamin B3 can damage the liver and too much vitamin B6 can lead to a loss of feeling in the arms and legs. The only vitamin that the UK’s health services recommend that everyone take is vitamin D, and then generally only in winter.
Multivitamin and mineral supplements such as Centrum Silver, the type used in this study, usually contain levels that are close to the recommended daily doses. “You’re not mega-dosing,” says Sesso.
To learn more about their potential benefits, Sesso and his colleagues randomly assigned 1000 participants, with an average age of 70, to take the supplement or a placebo. “This was a very rigorous randomised-controlled trial; double-blind, placebo-controlled,” says Steve Horvath at the University of California, Los Angeles, who wasn’t involved in the study. “That alone sets it apart from most of the supplement literature, which relies on observational data full of confounding [factors].”
Blood samples were taken from the participants at the start of the start of the study, after one year and after two years. The DNA of immune cells in their blood was then analysed to look for the presence or absence of epigenetic markers – chemical tags that get added to DNA – at specific sites in the genome.
The patterns of epigenetic markers change in a predictable way as people age, allowing researchers to roughly estimate how old they are from blood tests. A number of different epigenetic clocks of this kind have been developed, which vary based on which sites on the genome they look at.
Sesso’s team used five epigenetic clocks, which all suggested that the people taking multivitamins aged slightly less than those on placebo, but the results were only significant for two of the clocks. “The statistically significant results were for the second-generation clocks that other groups have shown to be the most reliable and sensitive for evaluating longevity interventions,” says Horvath, who develops epigenetic clocks.
The first-generation clocks are good at predicting a person’s age but many of the epigenetic markers they look at aren’t directly relevant to health, says Horvath. The second-generation clocks are based on markers linked to deteriorating health and the risk of dying. “I should note, however, that the effect sizes are modest,” he says. “This is not a fountain of youth.”
“The difference was very small relative to the variation observed in the trial participants prior to intervention,” says Daniel Belsky at Columbia University in New York.
The researchers claim that the slowing of epigenetic clocks they found is equivalent to about four months over the two-year period, but this may be misleading. One of the many issues with epigenetic clocks is that their estimates of how a slowing of the same magnitude translates into normal time vary widely between them, says Belsky.
Sesso acknowledges that it isn’t clear what these epigenetic measures mean in terms of people’s health. “We just don’t know how to translate clinically an improvement of four months of biological aging,” he says.
Most of the participants were of European descent, so it also isn’t clear if this slight slowing of epigenetic ageing will happen in non-European people, or in younger individuals. Nor do we know if the same results will occur with other types of multivitamins or if they will continue over periods longer than two years.
The study, which has now ended, also evaluated the effects of cocoa extracts, with some participants getting these in addition to multivitamins or instead of a placebo. The cocoa extracts had no significant effects on any of the epigenetic clocks.
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