Is It Possible To Take Too Many Vitamins?

Taking excess vitamins may not be such a good idea—for your wallet or your health.

For decades, we were taught that vitamins and minerals in pill form could help make up for deficiencies in the typical diet or provide health and energy boosts that food alone couldn't. In recent years, however, many scientists have changed their recommendations, as some studies show no evidence that most popular supplements have any real health benefits. Yet a 2016 study in JAMA suggested that people may be sticking with supplements. The study shows that more than half of US adults had taken a supplement in the past 30 days before answering the examination survey.

Will all those supplements actually do you any good? And more importantly, is it possible to take too many vitamins? We posed those questions to health and nutrition experts and dug into the latest research. Here's what we learned.

The Latest Science on Supplements

Scientists know that people who eat lots of vitamin- and mineral-rich foods tend to live longer and healthier lives. But when those nutrients are served up in pill form, it's still unclear whether they have the same effect. For example, a major 2019 study in the Annals of Internal Medicine found that taking dietary supplements does not appear to reduce the risk of cancer.

Other research, including a 2018 study in the Journal of the American College of Cardiology, found that regular supplement use has no net effect on heart health or risk of early death.

"We found a surprising neutrality of effects," lead author David Jenkins, MD, professor of medicine and nutritional sciences at the University of Toronto, told Health. "In other words, it didn't seem to do anything." Their findings were accurate for multivitamins and for vitamin C, vitamin D, and calcium supplements—all nutrients that have been touted for heart health in the past.

In light of these and other studies, most experts say that dietary supplements aren't all they were once made out to be. "For the average healthy person, you probably don't need a multivitamin, multimineral supplement," said Beth Kitchin, PhD, assistant professor of nutrition studies at the University of Alabama at Birmingham. "And you certainly don't need a lot of additional supplements on top of that."

In Moderation, Most Won't Hurt, and Some Might Help

That being said, Kitchin said that a multivitamin can help make up for some deficiencies in a person's diet, especially if they avoid certain food groups like meat or dairy. Kitchin also recommended calcium and vitamin D supplements to some patients who are at risk of osteoporosis, "but I always look at their diet first before prescribing them," Kitchin said.

Kitchin personally takes a daily multivitamin but only takes half a dose (one pill rather than a serving size of two). "I like to give myself a little extra insurance without overdoing it," Kitchin said.

If people choose to take a multivitamin, it's best to look for one with no more than 100% of the daily value for any one nutrient—and to avoid spending a lot of money, Kitchin said. "There's no strong evidence that it will help you, but as long as you keep the dose reasonable, it's also not going to hurt you," Kitchin said.

Dr. Jenkins also said that, when taken in moderation, most vitamin and mineral supplements won't cause harm. Dr. Jenkins also stressed that the 2018 study only looked at cardiovascular problems and early death and that supplements may still have benefits in other areas.

"We didn't look at overall health; we didn't look at whether people got beautiful hair or skin, or whether your bones got stronger," Dr. Jenkins said. "I'm not going to say that some supplements can't be good for you in those ways."

There Is Such a Thing As Too Many

But just because supplements are safe in moderation doesn't mean that more is better. Combining multiple supplements or taking higher-than-recommended doses can increase the risk that they can cause harm, said Kitchin.

"You really can't get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements," Kitchin said.

Taking high doses of vitamin C can lead to stomach cramping and diarrhea, for example. High doses of vitamin A, vitamin D, and other nutrients can lead to more serious, long-term complications—like liver and kidney problems or a dangerous hardening of blood vessels.

"We've learned a very important lesson, in that when we isolate these nutrients out of food and put them in super-high doses, we may have some unintended consequences," Kitchin said.

Even if none of your supplements individually exceeds the upper limit for a given nutrient, combining several pills—like a multivitamin and an additional vitamin D capsule, for example—may add up to higher-than-recommended doses. Supplements can also interact with each other, said Kitchin, or with medications you're already taking.

Always Run Things by Your Healthcare Provider

It's a good idea to talk with your healthcare provider about the supplements you're taking on a regular basis, said Kitchin, especially if you have a health condition, a dietary restriction, or you're on any type of medication. You should also run any new supplements you're considering by your provider or pharmacist before adding them to your regimen.

It's also important to focus on getting your nutrients from food first, said Dr. Jenkins, and not from supplements. "Pills are not a substitute for a good diet—plant-based, fruit, veggies, whole grains, nuts, and seeds," Dr. Jenkins said. "They are packed with what you need."

Was this page helpful?
Related Articles