No good evidence vitamins prevent heart disease or cancer, panel finds

Vitamins and supplements offer little to no benefit in preventing cancer or heart disease, according to a new review of 84 studies.

Based on that finding, an independent panel of the U.S. Preventive Services Task Force said Tuesday it had “insufficient evidence” to recommend or discourage the use of multivitamins or supplements to prevent these problems. health.

The review looked at the effects of popular supplements like beta-carotene, folic acid, calcium, magnesium, selenium, and zinc, as well as multivitamins and vitamins A, B, C, D, and E.

But the advice comes with caveats: It doesn’t apply to children, people with chronic conditions, or those with a known nutritional deficiency. The task force also recommended a daily folic acid supplement for people who are pregnant or planning to become pregnant.

For the average healthy adult, however, “there’s no reason to start taking dietary supplements more broadly,” said Dr. Howard Sesso, associate director of the Division of Preventive Medicine at Brigham and Women’s Hospital. . Sesso is not a member of the task force, but two of its studies were included in the review.

“For those who are currently taking a particular multivitamin, I don’t think that statement has to necessarily change what you do, but it’s always important to re-evaluate why you’re taking supplements,” Sesso said.

The US Task Force on Preventive Services last gave recommendations on vitamins and supplements to prevent heart disease and cancer in 2014.

Dr. Jenny Jia, professor of general internal medicine at Northwestern University Feinberg School of Medicine, said larger-scale studies have been published since 2014, “and we still don’t see any compelling evidence that vitamins and supplements in general are contributing to the prevention of heart disease and cancer.”

Jia co-wrote an op-ed published alongside the review on Tuesday, which said shopping for vitamins and supplements was essentially “wasted money.” In the United States, people spent nearly $50 billion on dietary supplements in 2021, the authors said.

“A healthy diet remains the first line of defense”

The new review found strong evidence that vitamin E in particular did not prevent cancer or heart disease, while beta-carotene was associated with an increased risk of lung cancer and death from heart disease. Therefore, the task force advised against taking either supplement to prevent heart disease or cancer, the same recommendation it gave in 2014.

Experts generally agree that instead of taking vitamins or supplements, a balanced diet rich in fruits and vegetables and regular physical activity are the best ways to reduce the risk of cancer or heart disease.

“What should be clear from these guidelines is that healthy eating remains the first line of defense against chronic disease prevention,” Sesso said. “Supplements should in no way be a crutch or a way to compensate for insufficient nutrition.”

But vitamins and supplements could have some benefits, he added, for older people who struggle to absorb nutrients from food. Sesso pointed to mixed evidence that multivitamins may reduce the risk of cataracts or age-related macular degeneration, or possibly delay cognitive decline.

“We still have a lot of work to do to really unravel that and look at other metrics beyond what these recommendations focus on, which is cardiovascular disease and cancer,” he said.

Even the relationship between multivitamins and cancer needs more research, he added, since the review found that multivitamins may be associated with marginal benefit for cancer outcomes. One of Sesso’s trials indicated that daily multivitamin use reduced overall cancer risk in male physicians. But another trial found no evidence that multivitamins reduced overall cancer risk in men or women.

“If there is an advantage, it’s very small,” Jia said.

Little FDA oversight for vitamins

Dietary supplements can be purchased without a prescription and do not require Food and Drug Administration approval. Because of this, Sesso said, manufacturers “have a lot more leeway with what they can say on their labels.”

“There’s a general perception that all of these dietary supplements are benign,” Jia said, “when we know that these supplements aren’t regulated to the same level as pharmaceutical drugs by the FDA. So we don’t have as much of a good idea of ​​their benefit/harm ratio.”

Sesso said it was possible for certain formulations to have different health effects.

“You don’t get the same range of vitamins and minerals in a gummy vitamin, just because of the nature of how they’re formulated compared to a typical tablet,” he said, adding, ” We don’t really have the type of clinical trial evidence to support whether or not these help, hurt or do nothing.”

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