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Analysis Food for Thought 2020

Health effects of vitamin and mineral supplements

BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m2511 (Published 29 June 2020) Cite this as: BMJ 2020;369:m2511

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  1. Fang Fang Zhang, associate professor1,
  2. Susan I Barr, professor2,
  3. Helene McNulty, professor3,
  4. Duo Li, professor4,
  5. Jeffrey B Blumberg, professor1
  1. 1Friedman School of Nutrition Science and Policy, Tufts University, Boston, USA
  2. 2University of British Columbia, Vancouver, Canada
  3. 3Nutrition Innovation Centre for Food and Health, Ulster University, Coleraine, UK
  4. 4Institute of Nutrition and Health, Qingdao University, Qingdao, China
  1. Correspondence to: F F Zhang fang_fang.zhang{at}tufts.edu

Growing numbers of healthy people are taking dietary supplements but there is little evidence that they protect against non-communicable diseases, say Fang Fang Zhang and colleagues

Vitamin and mineral supplements are the most commonly used dietary supplements by populations worldwide.1234 The amount of micronutrients they provide ranges from less than recommended intakes to much more, making them important contributors to total intakes. While supplements can be used to correct micronutrient deficiency or maintain an adequate intake, over-the-counter supplements are most often taken by people with no clinical signs or symptoms of deficiency. However, the effect of vitamin and mineral supplements on the risk of non-communicable diseases in “generally healthy” populations is controversial. We examine patterns of supplement use and the evidence on their effects from randomised trials.

Who uses supplements?

Vitamin and mineral supplements have a large worldwide market, but we will focus on their use in North America and Europe, where there is most evidence on patterns of use and health outcomes. The use of vitamin, mineral, and fish oil supplements5 is common among adults in North America (fig 1).6 The prevalence of use has increased for some individual nutrients—for example, there was a fourfold increase in use of vitamin D supplements among US adults from 1999 to 2012, excluding intake obtained from multivitamin and mineral.7 The use of omega-3 fatty acid supplements also increased sevenfold.7

Fig 1

Proportion of US adults taking commonly vitamin, mineral, and fish oil supplements, National Health and Nutrition Examination Survey 1999-20146

Supplement use is generally less prevalent in other countries than in the US and Canada but varies widely (eg, Denmark 51%, South Korea 34%, Australia 43%, UK 36%, Spain 6%, Greece 2%).234 Different methods for assessing supplement use may contribute to the different prevalence …

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