Nutritional supplements - vitamins, minerals, plants and probiotics - are more popular than ever. More than three-quarters of Americans take at least one, according to the Food and Drug Administration /FDA/.
Are any of them worth it? The experts' answer is tentative. Some vitamins, including multivitamins, have been shown to be helpful in large clinical trials. Others have been shown to potentially cause harm. Many supplements lie somewhere in between.
About 100,000 different supplements are sold in stores and online in the United States. They range from multivitamins to herbs and blends that promise weight loss. Some, however, may be toxic, and others are falsely claimed to improve brain function.
Robert F. Kennedy Jr, Donald Trump's pick for health secretary, told podcaster Lex Friedman in 2023 that he takes "a lot of vitamins and nutrients" that he can't list because he can't remember them all. In an October post on X, Kennedy accused the FDA of "aggressively suppressing" vitamins and supplements.
In fact, the FDA has limited oversight of supplements once they're on the market. In a published 2018 study, researchers from the California Department of Public Health raised concerns about products that contain unapproved and potentially dangerous ingredients.
The Health and Nutrition Supplement Education Act of 1994 puts them in the same category as foods. This framework means that the agency regulates dietary supplements as food products, not pharmaceuticals. As a result, oversight of their safety and efficacy is largely left to the companies that sell them.
Companies can also use a loophole called GRAS. This designation allows substances that are considered safe by research or because they are already used in certain foods to be used in new products. No notification to the FDA is required.
Many of the vitamins and minerals on the market are generally safe, but not always effective.
When it comes to research, understanding the effects that supplements have on human health is difficult, time-consuming and expensive, said Dr. David Serres, director of medical nutrition at the Institute of Human Nutrition at Columbia University Medical Center.
"Most of the research you hear about is observational, where two things are related but causation can't be established," Dr. Serres explained.
"Clearly there are supplements with established benefits," argued Christopher Gardner, a professor at Stanford University. "There are also a lot of supplements that are probably not beneficial but are also not harmful," he clarified.
More does not mean better
Manson, who led the COSMOS-Mind clinical trial on multivitamins, said people should be cautious about vitamins that contain "megadoses."
"You need to look at the packaging and see what it says in terms of a percentage of daily intake. Often it will say 400% or 500%, well above the value," she said.
Such high doses can be dangerous or just a waste of money.
There is some evidence that daily multivitamin intake may protect against memory loss; however, numerous studies have failed to show that supplements have miraculous health effects. A diet such as the Mediterranean diet, which is full of plants, vegetables and oily fish, may reduce the risks of dementia or heart disease, but supplements generally do not offer the same benefits, research has found.
I don't have an answer for why people take supplements that may provide little or no benefit, but it may be due to a strong desire to control their health, Ceres explained. | BGNES, AFP
