Health-conscious people may choose 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 reduce cognitive decline in people over 60. Now it seems that such supplements can also slow down aging more generally.
But this finding relied on an indirect measure of aging, so it’s not certain what this means in terms of health benefits. We are not yet at a point where it can be recommended that all older adults take multivitamins, says Howard Sesso of Harvard University. That said, there can be at least small benefits with very little risk. “There have been no harmful effects of a daily multivitamin that we have identified so far,” he says.
In the past it has been argued that taking individual vitamins can have various benefits, but we now know that this can also be harmful. For example, consuming too much vitamin A can weaken bones, excessive vitamin B3 can damage the liver and too much vitamin B6 can cause loss of feeling in the arms and legs. The only vitamin that UK Health Services recommends 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 close to the recommended daily doses. “You don’t megadose,” says Sesso.
To learn more about their potential benefits, Sesso and his colleagues randomly assigned 1,000 participants, with an average age of 70, to take the supplement or a placebo. “This was a very rigorous randomized controlled trial; double-blind, placebo-controlled,” says Steve Horvath of the University of California, Los Angeles, who was not 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 study, after one year and after two years. The DNA of the immune cells in their blood was then analyzed to look for the presence or absence of epigenetic markers – chemical marks that are added to DNA – at specific locations in the genome.
The patterns of epigenetic markers change in a predictable way as people age, allowing researchers to roughly estimate their age from blood samples. A number of different epigenetic clocks of this type have been developed, which vary based on which places on the genome they look at.
Sesso’s team used five epigenetic clocks, all of which suggested that the people who took multivitamins aged slightly less than those who got the placebo, but the results were only significant for two of the clocks. “The statistically significant results were for 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 are not directly relevant to health, says Horvath. The second-generation watches are based on markers linked to impaired health and risk of dying. “However, I should note that the effect sizes are modest,” he says. “This is not a fountain of youth.”
“The difference was very small compared to the variation observed in the trial participants before the intervention,” says Daniel Belsky of Columbia University in New York.
The researchers claim that the slowing down of epigenetic clocks they found corresponds to about four months over the two-year period, but this may be misleading. One of the many problems with epigenetic clocks is that their estimates of how a decline of the same order of magnitude translates to normal time vary widely between them, says Belsky.
Sesso acknowledges that it is not clear what these epigenetic measures mean in terms of people’s health. “We just don’t know how to clinically translate a four-month improvement in biological aging,” he says.
Most of the participants were of European descent, so it is also not clear whether this slight slowing of epigenetic aging will occur in non-European people, or in younger individuals. We also do not know if the same results will occur with other types of multivitamins or if they will continue for longer periods than two years.
The study, which has now ended, also evaluated the effects of cocoa extracts, with some participants receiving these in addition to multivitamins or instead of placebo. The cocoa extracts had no significant effect on any of the epigenetic clocks.
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