Illustrations by Kieran Blakey

The Elemental Guide to Vitamins

The latest science behind the 10 most popular, plus answers to that age-old question: Should you take them?

itamins and other supplements are more ubiquitous than ever: A 2019 Harris Poll found that 86% of Americans say they take them. But what does the science say about your go-to supplement? Elemental scrutinized the latest and best research on the 10 most popular supplements in America. Whether you’re taking something for your brain, your bones, or your blood, you’ll want to read this before you swallow another dose.

Click on each bottle to learn more.

While consumer enthusiasm for these pills and powders has never been greater, the science on many of these products is mixed or incomplete. “I think there’s this belief out there that most people have an underlying need for something, or that there’s a deficiency in their diet, but that’s probably not true,” says Edgar Miller III, MD, PhD, a professor of medicine at Johns Hopkins University. “We’re overfed and overnourished in the U.S.”

Since the early 2000s, Miller has conducted randomized controlled trials (RCTs) on a variety of popular vitamins and supplements. RCTs are generally considered the gold standard in clinical research because they involve splitting people into groups and then measuring the effects of a pill or other intervention against a placebo or “control” intervention. Over and over again, Miller says his trials have found that pills either do nothing for people’s health or come with unanticipated risks. “People would be better off spending their money on fruits and vegetables,” he says.

Others who have dedicated years to the study of supplements reiterate his warnings. “If you experiment on yourself with supplements, you can do real harm,” says Mark Moyad, MD, MPH, the Jenkins/Pokempner director of preventive and alternative medicine at the University of Michigan.

Moyad says many people approach vitamins and other supplements as though they were all upside, and this isn’t the case. Quality control issues, including the potential for heavy metal or pesticide contamination, is a problem that few consumers consider when shopping for supplements. “There are situations when a person can benefit from one of these products, but people should go pill-less until they really need a pill,” Moyad says.

On the other hand, Moyad says there are situations in which targeted, judicious supplement use can do “incredible good.” He says phase three clinical trials have found that a daily 1000 mg dose of nicotinamide, a form of vitamin B3, can significantly reduce the development of nonmelanoma skin cancers in people who have had skin cancers in the past. “But even with this, I wouldn’t take it unless I had recurrent skin cancers,” he says. “People need to start treating supplements like drugs,” meaning don’t take them until they’re needed.

And yes, sometimes a person may have a more mild deficiency, rather than a serious medical issue. Some people are low in vitamin D or B12, and a daily can make a significant difference in how they feel day to day. Knowing when a supplement is appropriate, and safe, is key for staying healthy.

This story is a part of The Elemental Guide to Vitamins. Here are the vitamins and supplements that are covered: multivitamins, vitamin D, vitamin C, calcium, B vitamins, omega-3, vitamin E, fiber, protein, and probiotics.

I write about health, science, and psychology. My work has appeared in Time magazine, the New York Times, Vice, and elsewhere. I live in Germany.