An influential group of experts is recommending that people not take beta carotene or vitamin E supplements in hopes of preventing cancer or cardiovascular disease, arguing that they provide no clear benefits and may actually raise the risk of these health problems. They’ve also concluded that there’s not enough evidence to recommend taking multivitamin supplements for preventing either condition.
The new guidance, released Tuesday, comes from the U.S. Preventive Services Task Force (USPSTF) — a government-funded but independent organisation staffed by outside experts on a voluntary basis. The task force routinely produces and updates recommendations on topics related to preventing illness, such as the need for cancer screening among the general public. Their advice is widely followed by doctors and can even affect insurance coverage.
In 2014, the USPSTF looked at the evidence for using supplements as a way to reduce the risk of cancer and cardiovascular disease. The theory goes that inflammation and oxidative stress can be major drivers in causing these conditions, and that taking supplements might provide enough of an anti-inflammatory or antioxidant effect to lower the average person’s odds of developing them. But back then, the experts found insufficient data to back up these claims, with the exceptions of beta carotene or vitamin E. For vitamin E, they found no strong evidence of a protective effect, and for beta carotene (the precursor to vitamin A), they actually found some evidence that taking these supplements regularly could raise the risk of cardiovascular disease and cancer.
Despite dozens of new relevant studies published since 2014 (84 in total were analysed by the task force), their latest recommendations haven’t changed. With moderate certainty, they found that the “harms of beta carotene supplementation outweigh the benefits for the prevention of cardiovascular disease or cancer.” They also found with moderate certainty that there is no “net benefit” of taking vitamin E. And they found insufficient evidence to recommend taking multivitamin or multimineral supplements for either condition.
In an accompanying editorial published today in JAMA by researchers from Northwestern Medicine, the authors go even further, arguing that supplements are effectively “wasted money” for the general public. They note that if these supplements do anything to reduce mortality for the average person, the benefit is probably very small. But even that benefit isn’t certain, since the field is cluttered with poorly done or non-standardised studies, while the products themselves aren’t regulated to anywhere near the same extent that drugs are. They also argue that the perception of supplements as a cure-all — fuelled by advertising from the billion-dollar supplement industry — is a potentially harmful distraction from activities that are more likely to improve people’s health, such as exercise or eating a more balanced diet.
There are certain groups who definitely do benefit from supplementation. Prenatal vitamins, for example, are recommended during pregnancy to ensure the growing foetus gets enough folic acid. Many people also tend to have lower, possibly insufficient levels of certain nutrients, such as vitamin D, so supplements on a case-by-case basis could help fill these gaps. But right now, about 52% of Americans are estimated to take supplements regularly, while about a third take a multivitamin. For most people, these updated recommendations indicate, that extra boost isn’t needed and could very well be harmful.