There is a widespread perception that dietary supplements are necessary for everyone because our diets are generally thought to be unable to provide everything we need to meet the demands of everyday life. It is also commonly assumed that taking various dietary supplements will help us live longer. Unfortunately, rigorous scientific evidence does not support these beliefs.
Myth: Everyone needs multivitamin supplements.
At the end of 2013, a systematic review (Fortmann, Burda et al., 2013) was published, evaluating all available studies on the role of vitamins and minerals in preventing cancer and cardiovascular disease. Altogether, these studies included more than 400,000 participants. What did the researchers find?
Two large-scale studies involving 27,658 participants suggested a modest reduction in cancer risk among men who took multivitamin supplements. One of the two studies also included women, but no benefit was observed in the female participants. Meanwhile, an analysis of methodologically robust studies involving nearly 325,000 participants found that vitamins A, C, D, and E, beta-carotene, folic acid, selenium, and calcium neither reduced nor increased the risk of cancer or cardiovascular disease.
Beta-carotene, however, was associated with an increased risk of death from lung cancer among smokers. This finding has been known for some time and is considered paradoxical because beta-carotene’s antioxidant properties were once thought to reduce the risk of lung cancer in smokers by neutralising the free radicals generated by tobacco smoke.
In 2022, the U.S. Preventive Services Taskforce conducted a meta-analysis (essentially a rigorous analysis of previously published studies) based on 84 trials involving data from more than 730,000 participants (O’Connor, Evans et al., 2022). Based on this evidence, the researchers found a slight reduction in the overall risk of cancer (about 7%) and lung cancer (about 25%). However, these findings were subject to multiple methodological limitations, making the potential benefits uncertain. Beta-carotene, with or without vitamin A, was associated with an increased risk of cancer and cardiovascular mortality. There was no evidence that vitamin D or vitamin E supplementation affected all-cause mortality, cardiovascular mortality, or cancer-related mortality. The evidence supporting the benefits of other dietary supplements was described as “equivocal, minimal, or absent.” The same meta-analysis also found that some dietary supplements were associated with increased health risks, including fractures (vitamin A), hemorrhagic stroke (vitamin E), and kidney stones (calcium and vitamin C).
There are certain groups of people for whom one or more dietary supplements are necessary: iron supplements for premenopausal women, folic acid or multivitamin and mineral supplements during pregnancy, vitamin B12 supplements for those following a strict vegetarian (vegan) diet, and so on. However, there is little evidence to suggest that everyone should routinely take such supplements. In a healthy, well-functioning world, a healthy person should be able to obtain the necessary nutrients from fruits, vegetables, and other foods—not from artificially manufactured supplements, even those derived from natural ingredients.
Should we take supplements every day?
In November 2013, The Wall Street Journal posed this question to a number of leading figures in the medical field (WSJ, 2013). The only respondent who gave an unequivocal, one-word answer—”yes”—was Fred Hassan, a chemist by training and former head of several pharmaceutical companies. Four others were more cautious, recommending at most a daily multivitamin, vitamin D for certain individuals, or supplement use only on a physician’s recommendation.
The remaining six respondents were generally skeptical:
With one exception—folic acid for women planning a pregnancy—healthy people who take vitamin supplements should be told that they are paying good money for a placebo effect (Gurpreet Dhaliwal, Professor of Medicine, University of California).
A balanced diet is all you need (Murali Doraiswamy, Professor of Psychiatry and Medicine, Duke University Medical Center).
People would benefit far more from focusing on healthy eating—a balanced diet can provide all the nutrients a person needs (David Blumenthal, president of a New York-based nonprofit organisation that supports philanthropic efforts to improve access to healthcare nationwide).
Stop buying vitamin supplements. Instead, use the money you save each month on something that will actually make you feel better—buy yourself a massage (Rita Redberg, Professor of Medicine and cardiologist at the University of California).
Perhaps we should spend less money on bottled supplements and more in the produce section of our grocery stores—or, better yet, in our own gardens (Carol Cassella, physician and author).
This text is based in part on a longer article published in the 2014 edition of Signs of the Times Romania.
Bibliography
- Fortmann, S. P., Burda, B. U., et al. (2013), “Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: An updated systematic evidence review for the U.S. Preventive Services Task Force”, in Annals of Internal Medicine, vol. 159, no. 12, pp. 824–834.
- O’Connor, E. A., Evans, C. V., et al. (2022), “Vitamin and mineral supplements for the primary prevention of cardiovascular disease and cancer: Updated evidence report and systematic review for the US Preventive Services Task Force”, in JAMA Internal Medicine, vol. 327, no. 23, pp. 2334–2347.
- Ubel, P. A. (2022), “Why too many vitamins feels just about right”, in JAMA Internal Medicine, vol. 182, no. 8, pp. 791–792.
- WSJ (2013) – “Should healthy people take vitamin supplements?”, in The Wall Street Journal (online), 24 November 2013, available at https://www.wsj.com/articles/SB10001424052702303653004579212241399057838 [accessed on 29 October 2023].