Are vitamins a complete waste of money?

Happy new year! How are those new year’s resolutions coming along? If you are anything like the majority of Canadians,[1] your commitment has already lapsed, but that doesn’t mean you should give up. Many of us are striving to be better in 2023. Taking vitamins can be an appealing option—no starving, chopping vegetables, or sweating at the gym; just purchase, pop, and improve. But is it really that simple?

In 2022, JAMA published a study conducted by the US Preventive Services Task Force to assess vitamin, mineral, and multivitamin supplementation to prevent cardiovascular disease and cancer.[2] It represents the most thorough meta-analysis to date of every randomized controlled trial of vitamin supplements in adults. The data did not provide a compelling endorsement for vitamins. In fact, an article on Medscape summarizing the research was titled “It’s official. Vitamins don’t do much for health.”[3] So, which is it? Are vitamins helpful or not? It turns out that the data are not as clear as we might hope for.

Let’s dig into the specifics a bit more. The JAMA study recommended against vitamin E and beta-carotene to prevent cardiovascular disease and cancer, with beta-carotene possibly increasing lung cancer risk in people who smoke or are exposed to asbestos. Regarding single agents (vitamin D, vitamin A, calcium, folic acid, vitamin B12, vitamin C, selenium, vitamin B3, and vitamin B6) and multivitamin supplements, it concluded that current evidence is insufficient to assess the benefits versus the harms of use. Pooled analyses did not show an effect on all-cause mortality, cardiovascular disease, or cancer, but the authors acknowledged the limited generalizability and heterogeneity of the data. Importantly, they also specified that their conclusions do not apply to children, hospitalized people, or those with a chronic illness or nutritional deficiency and reminded us that those who could become pregnant should take at least 0.4 mg of folic acid daily.

I am cognizant that there are many other determinants of health and the JAMA publication was looking only at prevention of cardiovascular disease and cancer. However, because these are Canada’s two leading causes of death,[4] they are appealing targets for any intervention intended to improve people’s lives. Canadians spend over $4 billion[5] annually on vitamins, minerals, and supplements, with the most commonly stated reason being “overall wellness.” Is their money going to waste?

What we can say is that vitamins are not universally beneficial. In some cases they can cause harm, such as vitamin A with reduced bone mineral density, toxicity, or teratogenicity, and vitamin D–associated hypercalcemia and kidney stones. In terms of other products, we may not yet know which supplements are preventive of what, or in whom. Although taking a daily vitamin is low-risk, I am concerned that some people do not read beyond the Google summary before clicking to purchase. Furthermore, it’s common to be taking more than one product and overlapping, thereby exceeding dose recommendations. Vitamin companies are clearly aware of consumers’ short attention spans and desire for a quick fix. Some products even list the “benefits” right in their names. Perhaps the clever intention behind the Medscape article’s oversimplified title was to elicit a pause; a concise interpretation of the data makes it easier to convey. But, as in many facets of medicine, more evidence and critical appraisal will be essential to inform our patients and help them navigate a potentially predatory market of unfounded promises.

As doctors we are often presented with a long list (or bag of bottles) of vitamins, supplements, tinctures, etc., which patients want us to review. “Are these pills worth taking, doctor?” they ask. How do you reply? It seems that, in many cases, the truth is that we really don’t know.
—Caitlin Dunne, MD, FRCSC

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References

1.    McGinn D. Set a new year’s resolution. When every day feels the same, having a goal to work towards will make a difference. The Globe and Mail. 1 January 2021. Accessed 7 December 2022. www.theglobeandmail.com/life/article-set-a-new-years-resolution-when-every-day-feels-the-same-having-a-goal.

2.    US Preventive Services Task Force. Vitamin, mineral, and multivitamin supplementation to prevent cardiovascular disease and cancer. US Preventive Services Task Force recommendation statement. JAMA 2022;327:2326-2333.

3.    Wilson FP. It’s official. Vitamins don’t do much for health. Medscape. 22 June 2022. Accessed 7 December 2022. www.medscape.com/viewarticle/975852.

4.    Statistics Canada. Leading causes of death, total population, by age group. 24 January 2022. Accessed 7 December 2022. www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=1310039401.

5.    Statista. Quarterly retail sales of vitamins, minerals and other health supplements in Canada from 1st quarter of 2014 to 4th quarter of 2021. Accessed 7 December 2022. www.statista.com/statistics/471444/quarterly-retail-sales-of-drugs-vitamins-and-supplements-canada (log in required).