Are nutritional supplements really effective? What to know about their popularity and limited regulation

Food supplements – vitamins, minerals, herbs and probiotics – are more popular than ever. More than three-quarters of Americans take at least one, according to the Food and Drug Administration.

Are any of them worth it? The research is mixed. Some vitamins, including multivitamins, have been shown to be beneficial in large-scale randomized clinical trials. Others have been shown to potentially cause harm. Many fall somewhere in between.

According to FDA estimates, up to 100,000 different supplements are sold in stores and online in the United States. They range from multivitamins to herbs to concoctions that promise weight loss, including some that may be toxic or falsely claim to improve brain function.

Robert F. Kennedy Jr., President-elect Donald Trump’s pick for health secretary, told podcaster Lex Fridman in 2023 that he takes “a ton of vitamins and nutrients,” which he said not being able to list because he “didn’t remember.” all. » In an article on X in October, Kennedy accused the FDA of “aggressive suppression” of vitamins and nutraceuticals, among other things.

In fact, the FDA has limited oversight over supplements once they are on the market. In a study published in 2018, researchers from the California Department of Public Health raised concerns about products containing unapproved and potentially dangerous ingredients.

The Dietary Supplement Health and Education Act of 1994 places dietary supplements in the same category as foods according to the FDA. This framework means that the agency regulates dietary supplements as food products rather than pharmaceutical products. As a result, monitoring the safety and effectiveness of products is largely left to the companies that sell them.

“The FDA does not approve dietary supplements or the labeling of their products before they are sold to the public,” said Dr. Cara Welch, director of the FDA’s Office of Dietary Supplement Programs at the Center for Health. food safety and applied nutrition, in an interview on the agency’s website. “In fact, most products can be legally placed on the market without the FDA even knowing. »

If a company wishes to sell a dietary supplement containing an ingredient that is not already present in foods sold in the United States, the company must submit a “new dietary ingredient” notification to the FDA, including a “prescription history.” use or other evidence of safety”. establishing that the dietary ingredient, when used under the conditions recommended or suggested on the labeling of the dietary supplement, is reasonably likely to be safe.

The FDA reviews notifications regarding safety concerns, but does not approve or reject the supplement based on the effectiveness of the ingredient.

“Only a tiny fraction of dietary supplements on the market have been rigorously tested for effectiveness or safety,” said Dr. JoAnn Manson, chief of the division of preventive medicine at Brigham and Women’s Hospital.

Companies can also use a loophole called generally recognized as secure, or GRAS. This designation allows the use in new products of substances deemed safe either because of research or because they are already used in food. No notification to the FDA is required.

“Companies can just declare something as GRAS and then add it to supplements, and the FDA will never know about it unless there is a major problem,” said regulatory advisor Jensen Jose at the Center for Science in the Public Interest, a nonprofit consumer association. defense group.

Research limitations

Many vitamins and minerals on the market are generally safe, if not always effective, and the agency has the authority to request a recall if a product causes unwanted side effects once consumers begin using it or if the company is caught making misleading claims. about a supplement. Some companies also voluntarily self-regulate.

“What we are doing in self-regulation goes beyond what is required by federal regulations,” said Steve Mister, president and CEO of the Council for Responsible Nutrition, a trade association and lobbying group that represents companies that make supplements. “There is a collective mindset that the industry must behave responsibly. »

When it comes to research, understanding the effects of supplements on human health is difficult, time-consuming and expensive, said Dr. David Seres, director of medical nutrition at the Human Nutrition Institute at Columbia University Medical Center.

“The majority of research that we hear about is observational, where two things are correlated but cause and effect cannot be established based on that research,” Seres said. “The majority of nutrition research tends to be these kinds of studies.”

“There are clearly supplements with established benefits,” said Christopher Gardner, a professor of nutrition at Stanford University. “There are also many supplements that are probably not beneficial, but are also not harmful.”

More doesn’t mean better

Manson, who led the COSMOS-Mind clinical trial of multivitamins, said people should be cautious of vitamins containing “megadoses.”

“You have to look at the level and see what it says in terms of percentage of daily intake. Often it will say 400% or 500%, well above the daily intake value,” she said.

Doses this high can be dangerous or a waste of money.

The U.S. Preventive Services Task Force, an independent group of medical experts who make recommendations for preventive and primary care, has issued a new recommendation against taking vitamin D to prevent falls and fractures in older people, based on evidence that this is not the case. This is not beneficial – unless someone has a diagnosed impairment.

There is some evidence that a daily multivitamin may protect against memory loss; However, many studies have failed to demonstrate that supplements have miraculous health effects. A diet like the Mediterranean diet, rich in plants, vegetables and oily fish, may reduce the risk of dementia or heart disease, but supplements generally don’t provide the same benefits, research shows.

“In general, we should be able to get all the nutrients we need from food, but the reality is that many people don’t always have access to a reasonable variety of healthy foods,” Gardner said, adding that People who don’t have access to a variety of nutritious foods may benefit from certain supplements.

For everyone, more doesn’t mean better.

“Most Americans meet all of their vitamin, mineral and nutrient needs. If the intake is already sufficient, it is rare that additional intake is useful,” he added.

There’s no single answer to why people take supplements that provide little or no benefit, but it may be due to a strong desire to control their health, Seres said.

“The talk of benefit is a strong temptation when we assume it can’t be harmful and the airwaves are filled with ‘supports XYZ health,'” he said.