Millions of people who take daily multivitamins may not be reaping the perceived health benefits, according to a new study published in the Journal of the American Medical Association.
One in three American adults take a daily multivitamin to ward off disease, but studies suggest that multivitamins don’t help you live longer.
The study, which looked at nearly 400,000 generally healthy adults over a 20-year period, found no evidence that long-term daily use of a multivitamin reduced the risk of death. Instead, in the early stages of the study, people who took multivitamins had a 4% higher risk of death.
“The findings will be disappointing for anyone who thought taking a multivitamin would extend their lifespan – they don’t, and this adds to other studies that have shown more or less the same thing,” said Dr Neal Barnard, who wrote a commentary on the study.
Dr Bernard said some people, such as pregnant women and those with macular degeneration, could benefit from taking a multivitamin, and there is also some evidence to suggest it could reduce the risk of dementia later in life.
“That’s the good news, but there’s also some pretty bad news,” Bernard says. “Multivitamins give you a lot of vitamins together, some of which can actually be harmful if you take too much.”
The biggest risk is the iron added to vitamins, which can be harmful to people who already get enough iron in their diet: Too much iron can lead to heart disease, Bernard said.
The nutrients copper and beta-carotene can also be harmful in excess: Excessive copper has been linked to Alzheimer’s disease, and the vitamin form of beta-carotene may increase the risk of cancer, according to Bernard.
He said these “toxic effects” may be responsible for the increased mortality rates early in the study.
“It’s better to get your vitamins from food because that’s where you’re getting all the vitamins that nature provides,” Bernard says.
“What you really need to look for are vegetables and fruits. And eat lots of them.”
Bernard said some people may need to supplement with certain vitamins, such as vitamin B12 and vitamin D, which he said are best taken as individual supplements rather than a multivitamin.
