It is worth taking vitamins and supplements? For most people, probably not

The US Preventive Services Task Force says there isn’t good evidence that supplements protect against cancer or heart disease in most people

By Grace Wade

It is unclear whether dietary supplements help protect against cancer or cardiovascular disease in most adults, and one kind of supplement may actually increase cancer risk, according to updated recommendations from the US Preventive Services Task Force. 

More than half of US adults take supplements. Many perceive them as beneficial to their health and as a way to fill nutrient gaps in their diet.  

The new guidelines challenge this widely held perception. The task force is made up of 16 independent medical experts and provides guidance on preventive health measures such as screenings, counselling services and medication. To develop the latest recommendations, it reviewed 84 studies on supplement use, 54 of which were published after the group last issued advice on supplements in 2014.  

“For most vitamin and mineral supplements, including combinations like multivitamins, we couldn’t find enough evidence to recommend for or against their use in preventing cardiovascular disease and cancer with some exceptions,” the organisation’s vice chair Michael Barry told New Scientist.  

The task force specifically recommended against vitamin E and beta-carotene supplements. It found vitamin E supplements had no beneficial effect in preventing premature death, cardiovascular disease or cancer. The evidence also indicates beta-carotene — a pigment converted to vitamin A in the body — may increase the risk of lung cancer in people who smoke or were exposed to asbestos, says Barry.  

The task force clarified that these new recommendations don’t apply to those with vitamin and mineral deficiencies or people who are or may soon become pregnant. “In that case, we have a separate recommendation on the use of folic acid supplements to prevent neural tube defects in the developing baby,” says Barry.  

But for most people, dietary supplements are probably a waste of time and money, according to a commentary written by researchers at Northwestern University in Illinois to coincide with the publication of the new recommendations. “We’re seeing that vitamins and supplements, unfortunately, are not a silver bullet for healthy Americans,” says lead author Jenny Jia. “Most people do assume that vitamins are completely benign, but we can see, in some cases, that they can be harmful.”   

Taking supplements may also provide people with a false sense of security, says Barry. As a result, they may forgo other, more effective, measures for preventing cancer and cardiovascular disease like eating a healthy diet high in fruits and vegetables, exercising and following recommendations for cancer screenings.   

Journal reference: JAMA, DOI: 10.1001/jama.2022.9167