There is no evidence to support claims recently made online that vitamin D is “the most effective medicine against cancer” or that taking the vitamin prevents cancer or lowers the odds of dying from the disease, according to scientific analyses.
A tweet posted on Oct. 6 by @thehealthb0t claims, without citing any evidence that Vitamin D is “the single most effective medicine against cancer, far outpacing the benefits of any cancer drug known to modern science.” The post has received over 1,600 likes and more than 450 retweets at the time of writing(here) .
However, a 2022 evidence review by the U.S. Preventive Services Task Force, an independent group of scientists, found that taking Vitamin D has no effect on cancer incidence or deaths in the general population (here) (here) .
The large, rigorous analysis looked at the body of existing research on multivitamins and single vitamins, and their effects on the incidence of cancers or heart disease. For Vitamin D, it found that “use was not significantly associated with all-cause mortality, cardiovascular, or cancer outcomes.”
Jeffrey Linder, chief of general internal medicine at Northwestern’s Feinberg School of Medicine, who co-wrote an editorial accompanying the study (here) , told Reuters Fact Check that “those who have low vitamin D levels have other factors that lead them to a higher risk for cancer.” He added: “It’s never been shown, among healthy adults, that supplementation with vitamin D reduces the risk of cancer.”
A U.S. clinical trial that tested vitamin D supplementation in more than 25,000 adults also found no effect in reducing cancer incidence. But the researchers noted a possible “signal” of reduced cancer deaths that needed further study (here) . In a follow-up analysis of the data (here ) , the same team found that taking vitamin D was associated with lower incidence of advanced cancers, but only among normal-weight individuals.
The researchers concluded that more study was needed to understand the apparent effect. If it can be confirmed, they said vitamin D might help slow cancer progression at lower cost than current cancer drugs,
“Even if vitamin D effects were modest, vitamin D supplementation at the studied levels is much less toxic and lower cost than many current cancer therapies.”
The researchers, however, did not suggest it would be more effective than existing cancer treatments.
Misleading. There is no evidence that vitamin D prevents cancer, or treats cancer more effectively than existing medicines. A large research review found no effect on cancer incidence or mortality from taking vitamin D. A large clinical trial found a possible slowing of cancer progression in people who do develop tumors, and concluded that if the effect could be confirmed, vitamin D might provide a “modest” benefit.
This article was produced by the Reuters Fact Check team. Read more about our fact-checking work (here) .