Apr 2nd 2026|3 min read
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Ask a doctor about vitamin supplements, and they are more than likely to tell you that all the pills do is help you produce “expensive urine”. In 2013 an editorial in the Annals of Internal Medicine appeared to end the argument by urging people to stop wasting their money. The evidence, however, is more positive than that advice might suggest.
Hints of benefits from multivitamin supplements go back to 2001—in a study of more than 3,500 people, co-funded by America’s National Institutes of Health, researchers gave high doses of vitamins C and E, zinc and beta carotene to those with age-related macular degeneration, the most common form of vision loss in older people. They found that the vitamins reduced the risk of progressing to advanced disease by 25%. (It wasn’t all good: the formulation eventually had to be adjusted to remove beta carotene, which was later linked to increased incidence of lung cancer in people with a history of smoking.)
More recent work also points to small benefits. The COSMOS trial conducted in more than 21,000 older American adults between 2015 and 2020 found that, in a subset of participants involved in three follow-up studies, those who took multivitamins seemed to have improved scores in cognition and episodic memory, which involves the recall of personal experience, events and situations. Over two or three years of treatment the cognitive scores of those on a daily multivitamin were equivalent to those of people who were two years younger.
Not all experts are convinced by this relatively modest evidence. But the potential benefits for older and largely well-nourished adults fit with the emerging understanding of how ageing bodies process nutrients. As people age, the gut’s ability to absorb certain vitamins, such as B12, declines, and the skin becomes less efficient at synthesising vitamin D from sunlight.
But how multivitamin supplements might lead to those observed benefits is a mystery. One hypothesis is that the vitamins tackle “subclinical” deficiencies (ie, conditions without noticeable symptoms) in these adults. Research on vitamin B also suggests that deficiencies can elevate levels of a compound in the body tied to oxidative stress and inflammatory damage in older adults.
Further digging by the COSMOS researchers continues to prove intriguing: on March 9th they reported that, in a subgroup of fewer than 1,000 people, taking a daily multivitamin for two years seemed to slow the rate at which genes acquired chemical tags used by scientists to estimate biological ageing. The effect was small, amounting to an apparent slowdown in ageing of a few months. It is not yet known, however, whether this change in methylation translates into longer life or fewer diseases.
Older adults are not the only group that could benefit. There are reasons to think that children with restricted eating patterns and those with ADHD or emotional-regulation issues could also benefit from targeted supplementation under the guidance of a doctor.
For young, healthy adults, there is little evidence that multivitamins are needed. But two points are worth considering. First, everyone differs in their genetics, their nutrition and how efficiently they absorb vitamins from the food they consume. Second, the recommended daily allowances for vitamins have been set at the levels needed to avoid known diseases—and not to optimise brain health over a lifetime. Those two targets may well not be the same. ■
This article appeared in the Science & technology section of the print edition under the headline “Are multivitamin pills worth taking?”
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