Vitamin and mineral supplements
Dietary supplements are widely used and offer the potential to improve health if appropriately targeted to those in need. Inadequate nutrition and micronutrient deficiencies are prevalent conditions that adversely affect global health. Although improvements in diet quality are essential to address these issues, dietary supplements and/or food fortification could help meet requirements for individuals at risk of deficiencies. For example, supplementation with vitamin A and iron in developing countries, where women of reproductive age, infants and children often have deficiencies; with folic acid among women of reproductive age and during pregnancy; with vitamin D among infants and children; and with calcium and vitamin D to ensure bone health among adults aged ≥65 years.
Intense debate surrounds the benefits of individual high-dose micronutrient supplementation among well-nourished individuals because the alleged beneficial effects on chronic diseases are not consistently supported. Daily low-dose multivitamin supplementation has been linked to reductions in the incidence of cancer and cataracts, especially among men. Baseline nutrition is an important consideration in supplementation that is likely to modify its effects. [1]
More women than men use supplements.[2]
Are supplements needed?
Despite the high use of supplements, inadequate intakes of micronutrients are still common in high income countries, where dietary patterns are typically energy rich but nutrient poor.
Prevalence of inadequate and excess nutrient intake among US Adults, National Health and Nutrition Examination Survey 1999-2014.2
In low and middle income countries, where specific micronutrient deficiencies are prevalent (eg, of iodine, iron, zinc, and vitamin A), supplementation is recommended when food based approaches such as dietary modification, fortification, or food provision are unable to achieve inadequate intake.[3] In the US and other countries, food fortification and enrichment such as the addition of iodine to salt, vitamin D to milk, and B1 and B3 vitamins to refined flour have contributed to the virtual elimination of their syndromes of deficiency (goitre, rickets, beriberi, and pellagra, respectively).[4] [5]
The widespread use of vitamin and mineral supplements in high income countries seems to contribute to an increase in population prevalence of intake above the upper tolerable level.2 Although the overall proportion of US adults with intakes above the upper level is below 5% for most nutrients, some population subgroups may have high rates of excess intake. For example, in a Canadian national survey, over 80% of children aged 1-3 years who took dietary supplements consumed vitamin A and niacin at levels above the upper limit.[6] In the US, excessive intake was noted for vitamin A (97%) and zinc (68%) among toddlers who were given supplements.[7] High quality evidence is lacking on the long term adverse effects of excess intake for several nutrients so it is unclear whether this is a cause for concern.
It remains controversial whether supplements are effective in reducing the risk of non-communicable diseases. In contrast to results of observational studies, the accumulated evidence from randomised controlled trials does not support benefits of supplements in reducing risks of cardiovascular disease, cancer, or type 2 diabetes in healthy people with no clinical nutritional deficiencies.1
[1] Susanne Rautiainen , JoAnn E Manson , Alice H Lichtenstein , Howard D Sesso : Dietary supplements and disease prevention - a global overview, https://pubmed.ncbi.nlm.nih.gov/27150288/
[2] Chen F, Du M, Blumberg JB, et al. Association among dietary supplement use, nutrient intake, and mortality among US adults: a cohort study. Ann Intern Med 2019;170:604-13. 10.7326/M18-2478 [PMC free article] [PubMed] [CrossRef] [Google Scholar]
[3] Bailey RL, West KP, Jr, Black RE. The epidemiology of global micronutrient deficiencies. Ann Nutr Metab 2015;66(Suppl 2):22-33. 10.1159/000371618 [PubMed] [CrossRef] [Google Scholar]
[4][4] Bishai D, Nalubola R. The history of food fortification in the United States: its relevance for current fortification efforts in developing countries. Econ Dev Cult Change 2002;51:37-53 10.1086/345361 [CrossRef] [Google Scholar
[5] Institute of Medicine Committee on Use of Dietary Reference Intakes in Nutrition Labeling Dietary reference intakes: guiding principles for nutrition labeling and fortification. National Academies Press, 2003. [Google Scholar]
[6] Shakur YA, Tarasuk V, Corey P, O’Connor DL. A comparison of micronutrient inadequacy and risk of high micronutrient intakes among vitamin and mineral supplement users and nonusers in Canada. J Nutr 2012;142:534-40. 10.3945/jn.111.149450 [PubMed] [CrossRef] [Google Scholar]
[7] Briefel R, Hanson C, Fox MK, Novak T, Ziegler P. Feeding Infants and Toddlers Study: do vitamin and mineral supplements contribute to nutrient adequacy or excess among US infants and toddlers? J Am Diet Assoc 2006;106(Suppl 1):S52-65. 10.1016/j.jada.2005.09.041 [PubMed] [CrossRef] [Google Scholar]
Buyer's guide
Also check out other topics