• Vitamin supplements may not actually provide the benefits people think they do
  • Scientists say the harms of taking beta carotene "outweigh the benefits"
  • Supplements can have health benefits "in the right circumstances"

Does taking lots of vitamins and minerals have any health benefits? They may be a "waste of money" for most people, while some may even have harmful effects.

For many people, vitamins and other supplements are already a part of their daily lives. However, they may not actually provide the benefits and protection people think they do, according to an update from the U.S. Preventive Services Task Force (USPSTF).

The USPSTF is an independent panel of experts that makes "evidence-based recommendations on clinical preventive services," Northwestern University explained in a news release. And in their latest update, experts said the "evidence is insufficient" that taking multivitamin supplements, paired supplements or single supplements can help prevent cardiovascular disease or cancer among healthy, non-pregnant adults.

"Inflammation and oxidative stress have been shown to play a role in both cardiovascular disease and cancer, and dietary supplements may have anti-inflammatory and antioxidative effects," researchers wrote in their paper, published Tuesday in JAMA.

Inflammation and oxidative stress are said to be the two most common causes of death in the U.S. annually.

"This has served as a rationale for proposing dietary supplements as a means to prevent both cardiovascular disease and cancer," the research team added.

In an accompanying editorial, also published Tuesday in JAMA, scientists from Northwestern Medicine explained that the term "insufficient evidence" doesn't necessarily mean they are recommending against their usage, but that "any potential benefits of a multivitamin on reducing mortality are likely to be small."

While the task force found "little evidence" of serious harm in most of the vitamins and nutrients that they reviewed, they concluded that the harms of taking beta carotene supplements "outweigh" their benefits. They noticed an increased risk of lung cancer among those who smoke tobacco or have occupational exposure to asbestos. The team also found, "with moderate certainty," that taking vitamin E has "no net benefits" in preventing cardiovascular disease or cancer.

"The USPSTF recommends against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer," the scientists wrote in their paper.

Focusing on supplements a 'potentially harmful distraction'

"The task force is not saying 'don't take multivitamins,' but there's this idea that if these were really good for you, we'd know by now," said Dr. Jeffrey Linder of Northwestern University Feinberg School of Medicine.

In the editorial, the scientists explained that supplements can have health benefits "in the right circumstances," for instance when a person has vitamin and mineral deficiencies. They also stressed that the guidelines don't apply to pregnant women or those who are planning to get pregnant soon since they are actually recommended to take folic acid and iron.

Supplements such as calcium and vitamin D may also help in preventing fractures and falls among older adults.

"Patients ask all the time, 'What supplements should I be taking?' They're wasting money and focus thinking there has to be a magic set of pills that will keep them healthy when we should all be following the evidence-based practices of eating healthy and exercising," said Linder.

A National Health and Nutrition Examination survey found that about 52% of adults in the U.S. used at least one dietary supplement in the last 30 days, while 31% reported using a multivitamin-mineral supplement, the team wrote in their paper. The most common reason for taking such supplements was said to be for "overall health and wellness and to fill nutrient gaps."

"Beyond wasted money, the focus on supplements might be viewed as a potentially harmful distraction," the experts wrote. "Rather than focusing money, time, and attention on supplements, it would be better to emphasize lower-risk, higher-benefit activities. Individual, public health, public policy, and civic efforts should focus on supporting people in regular preventive care, following a healthful diet, getting exercise, maintaining a healthy weight, and avoiding smoking."

An illustration picture taken in Lille, France, shows pills, tablets, caplets and capsules of medicine, May 7, 2017. Getty Images