Should You Take Supplements? A Doctor Reveals the Only 2 That Are Actually Worth It

Walk into any drugstore in America and there will be at least one entire aisle dedicated to supplements that all claim to support better health. Listen to every claim associated with those supplements and you might find yourself with a Stanley cup full of pills to take every morning.

But of all the supplements out there, are there any that are actually worth taking? According to nutrition experts, the answer is far simpler than you might think.

Does anyone need supplements?

Most healthy people can get all the vitamins and minerals they need from their diet, according to JoAnn Manson, professor of medicine at Harvard Medical School and chief of the Division of Preventive Medicine at Brigham and Women's Hospital. “Dietary supplements will never be a substitute for a healthy diet and healthy lifestyle,” Manson tells Inverse.

In fact, David Seres, professor of medicine at Columbia University Medical Center’s Institute of Human Nutrition, takes this assertion one step further: “Almost nobody needs to take supplements,” he tells Inverse. The exceptions to the rule, he says, are people with a deficiency or people with a disease that predisposes them to a deficiency, both of whom should seek counsel on supplements from their doctors.

According to Seres, no trial has demonstrated that any supplement is significantly and consistently beneficial. At their worst, supplements can be harmful. He cites a 2011 study of more than 35,000 people that found an increased risk of prostate cancer associated with those who took high doses of vitamin E. Manson adds that consulting your doctor before taking supplements is crucial because they may interact in undesirable ways with medications.

On top of all this, in the United States, supplements are regulated by the Food and Drug Administration as food, not drugs. So, the over 90,000 available options are not subject to the same rigor as medications. It’s also difficult to evaluate how well they work because reliable randomized controlled trials are time- and money-intensive, while observational studies do little more than yield associations rather than concrete cause and effect.

The two supplements that might be worth taking

In 2018, Manson led a large randomized controlled trial called VITAL that analyzed over 25,000 healthy participants who took either a vitamin D supplement, omega-3 supplement, or placebo for an average of 5.3 years. The trial’s results show that daily vitamin D was associated with a lower risk of cancer death. VITAL is the largest and longest randomized trial investigating whether high doses of vitamin D and omega-3 could, over time, reduce the risk of cancer, heart disease, and stroke.

Vitamin D helps absorb calcium from our intestines, which makes it crucial for bone health. We get most of our vitamin D from the sun, and some from oily fish and fortified dairy. This vitamin has received plenty of attention as a multitasking supplement that can improve everything from osteoporosis prevention to weight regulation, some of which VITAL dispels. For example, the findings show that 2,000 IU daily doesn’t lower the risk of cancer or heart disease, nor does it prevent bone fracture. Still, Vitamin D is one supplement that, for Manson, the positives may outweigh any negatives.

“Vitamin D is essential to good health, but we require only a small amount in order to achieve those benefits,” Manson says. “More is not necessarily better.” Regarding dose, the National Institutes of Health’s Office of Dietary Supplements recommends we get 600 to 800 international units (IU) of vitamin D every day. VITAL’s 2,000 IU is “fine,” Manson says, though consumers should stay away from “mega-doses” approaching 10,000 IU, which can be toxic.

A meta-analysis published in 2019 in the British Medical Journal of vitamin D studies also found that the supplement was linked to a 16 percent decrease in the risk of cancer death. Another review from 2014 of 159 trials found that vitamin D “seemed to decrease mortality in elderly people living independently or in institutional care.” Both papers called for further research, too.

The other big supplement worth considering, according to Manson, is omega-3 fatty acids, found in products like fish oil capsules. These are building blocks of fat that also come from oily fish as well as flaxseed, Brussels sprouts, and walnuts.

The VITAL study found that one gram daily of omega-3s was associated with a 28 percent reduction in heart attacks and a nearly 20 percent reduction in the incidence of autoimmune diseases. Manson stipulates that the benefits are most pronounced among people whose diet didn’t already include fish, so they stand to gain the most from these supplements. Additionally, a review published in 2017 identified omega-3’s importance to the gut microbiota and immunity but also called for more research. Another review concluded that omega-3 supplementation lowers the risk of chronic heart disease and death from chronic heart disease.

Still, Seres isn’t convinced. He says that VITAL’s results aren’t consistent with other, “albeit smaller” studies, and long-term effects are still unknown. Even if these vitamins coincided with some benefits, he points out they don’t seem to prevent more common diseases like heart disease. Ultimately, “the results in combination with all of the other research is not compelling.” In addition, he wouldn’t “support a blanket statement that people who want to prevent autoimmune disease should consider taking vitamin D.”

As for the meta-analyses, Seres sees that their calls for further research indicate inconclusiveness. “When you come to the conclusion after meta-analysis that more studies are required, it means, ‘We don't know. There's not enough data, there's not the strength of data, there's not a big enough difference to say anything conclusively,” Seres says.

In line with Seres, Manson advocates “precision nutrition,” tailoring supplemental nutrition depending on each person’s needs. Also in line with VITAL’s findings, she says that people who consume little to no fish and are predisposed to autoimmune diseases stand to benefit from omega-3s, while people who don’t get much sun, eat little dairy, and are at a higher risk of cancer “might want to hedge their bets and take a moderate dose supplement” of vitamin D.

Some studies may sing supplements’ praises a little too loudly for what the research does or doesn’t tell us, but randomized studies like VITAL keep expectations in check. “I think the evidence is more rigorous in randomized trials,” Manson says. “But, it's limited to a few health outcomes.”

Editor’s Note: A previous version of this story stated that the Food and Drug Administration does not regulate supplements. This is false. Supplements are regulated by the FDA but as food, not drugs.