Dietary supplements (vitamins, minerals, botanicals, and probiotics) are more popular than ever: More than three-quarters of the U.S. population takes at least one, according to the Food and Drug Administration (FDA).
But are any of them worth it to improve our health? The researchers’ conclusions are mixed. Some vitamins, including multivitamins, have been shown to be beneficial in large randomized clinical trials. Others have been proven to cause harm. And many are somewhere in between.
The FDA estimates that up to 100,000 different supplements are sold in stores and online in the United States, ranging from multivitamin products to herbs and concoctions that promise weight loss, including some that may be toxic or falsely claim to improve brain activity.
Robert F. Kennedy Jr., President-elect Donald Trump’s nominee for Secretary of Health, said in a 2023 interview that he takes “a ton of vitamins and nutrients,” to the point that he couldn’t list them because “I couldn’t remember them all.” And in an October message on the X network, he accused the FDA of “aggressive suppression” of vitamins and nutraceuticals, among other things.
The FDA has limited oversight power 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 placed dietary supplements in the same category as foods. The FDA regulates them as food products rather than pharmaceuticals. As a result, oversight of 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,” says Dr. Cara Welch, director of the federal agency’s Office of Dietary Supplement Programs at the Center for Food Safety and Nutrition. Applied. “In fact, most products can be legally placed on the market without the FDA knowing,” he adds in an interview on the agency’s website.
If a company wants to sell a dietary supplement that contains an ingredient that is not present in foods sold in the United States, it must submit to the FDA a “new dietary ingredient” notification with a “history of use or other evidence of safety.” that proves that the ingredient, when used under the conditions recommended or suggested in the dietary supplement labeling, is reasonably expected to be safe.”
The FDA then reviews those notifications for safety concerns, but does not approve or reject the supplement based on the effectiveness of the ingredient.
“Only a small fraction of the dietary supplements on the market have been rigorously tested for effectiveness or safety,” says Dr. JoAnn Manson, chief of the division of preventive medicine at Brigham and Women’s Hospital.
Companies can also use a loophole known as “generally recognized as secure” (GRAS). This designation allows the use of substances considered safe based on scientific research or because they are already used in foods, without the need to notify the FDA.
“Companies can simply declare a supplement as GRAS and then add it, and the FDA will never know unless there is a major problem,” says Jensen Jose, regulatory counsel at the Center for Science in the Public Interest, an advocacy group. non-profit consumer.
Limits to research
Many of the vitamins and similar products on the market are typically safe, although not always effective, and the FDA has the authority to recall a product if it causes adverse effects when consumers first start using it or if the company selling it makes false promises about it. its effectiveness.
Some companies often voluntarily self-regulate. “What we do goes above and beyond what federal regulations require,” says 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 needs to behave responsibly,” adds Mister.
When it comes to research, understanding the effects of supplements on human health is difficult, time-consuming and expensive, says Dr. David Seres, director of medical nutrition at the Institute of Human Nutrition at the University of California Medical Center. Columbia.
“Most nutrition research tends to be observational studies: two things are correlated but the cause-effect relationship cannot be established based on them,” he points out.
“There are clearly supplements with established benefits,” says Christopher Gardner, a nutrition professor at Stanford University. He adds: “There are also many supplements that are probably not beneficial, but not harmful either.”
More is not better
JoAnn Manson, who led the COSMOS-Mind clinical trial on multivitamins, says people should be careful about vitamins that contain “a megadose.”
“You need to look at the level and see what it says as far as percentage of daily intake. It will usually say 400% or 500%, much more than the daily intake value,” he explains.
Doses this high can be dangerous or a waste of money.
The Preventive Services Task Force, an independent group of medical experts who make recommendations on preventive and primary care, just wrote a new opinion that advises against taking vitamin D to prevent falls or fractures in older people, based on evidence showing that It offers no benefits unless someone has been diagnosed with a deficiency.
There is evidence that daily multivitamins can protect against memory loss; However, various studies have been unable to demonstrate that supplements have miraculous effects on health. A diet like the Mediterranean, of plants, vegetables and fatty fish, can reduce the risks of dementia and heart problems, but supplements usually do not guarantee the same benefits, according to research.
“We can generally get all the nutrients we need from food, but the reality is that many people do not always have access to a reasonable variety of healthy foods,” says Gardner, and those who cannot consume them could benefit from supplements.
For everyone else, more doesn’t mean better.
“Most Americans get all their vitamin, mineral and nutritional needs. If intake is adequate, help is rarely needed,” he added.
There is no single answer as to why people take supplements that may be giving them little or no benefit, but it may be due to a strong desire to have control over their health, Seres said. “The hint of a benefit is a strong temptation when it is assumed that it will not be harmful and the waves are filled with ‘supports the health of XYZ,’” he concludes.
