You probably have a jar of multivitamins somewhere in your house. And it’s probably useless.
There’s a good reason we thought they were necessary: For centuries, sailors who spent enough time at sea would often become lethargic, bleed from their gums, lose their teeth, and bruise like crazy. Then, in the 18th century, a British Naval Surgeon noticed (paywall) that giving them fruits like oranges and lemons relieved their symptoms. This was simultaneously the discovery of scurvy, and one of the first realizations that illness could sometimes be prevented with a little nutritional supplement.
As scientists learned more about the various roles vitamins and minerals play in human health, the nutrition industry got to thinking: What if you could combine all the essentials into one daily pill? Thus in the early 1940s, multivitamins—which include almost every micronutrient we need to function—were born. Since then, they’ve become a staple in bathroom medicine cabinets.
But, for most people living today, there is no reason to take a multivitamin. A meta-analysis published yesterday (May 28) looked through all the randomized studies from Jan. 2012 to Oct. 2017 on multivitamins, some combination pills that include one or two vitamins like calcium and vitamin D, and their connection to heart disease. After narrowing the dataset to just the 179 randomized-controlled studies—the highest standard of medical research—the researchers determined that “conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated.”
Today, our diets are a lot better than they used to be; in most countries, we have access to all kinds of foods thanks to the global food trade—which means we don’t need multivitamin pills to fill in any nutritional gaps. That said, those who have dietary restrictions that limit their sources of particular vitamins and minerals may benefit from taking a multivitamin—but there are also individual supplements that may work, too.
The meta-analysis found that some individual vitamins may have associated benefits or risks. Folic acid, for example, seemed to lower risk of heart disease. Antioxidants and niacin, or vitamin B-3, were found to increase the risk of death ever so slightly. But without a causal mechanism, or more specific data, the evidence isn’t enough to say that anyone should or shouldn’t take supplements with those ingredients. Some people who take niacin as a prescription to control their cholesterol, in fact, may still benefit greatly from taking it every day.
But multivitamins—not so much. “Our review found that if you want to use multivitamins, vitamin D, calcium, or vitamin C, it does no harm—but there is no apparent advantage either,” David Jenkins, a nutritionist at the University of Toronto and St. Michael’s Hospital, said in a statement.
Still, the fact that these vitamins are harmless doesn’t mean that you should eat them by the handful.