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More than half of American adults and about 30% of American children report taking vitamins or other dietary supplements, fueling a $40 billion a year industry that the Food and Drug Administration (FDA) estimates has put 80,000 or more products on the market. Vitamin and mineral supplements are recommended by doctors for the elderly, pregnant women, and other populations at risk of specific nutrient deficiencies. However, there is little evidence that supplements benefit generally healthy people, and some studies have identified potential harms. Variations in how individuals absorb nutrients, and the routine addition of vitamins and minerals to several common foods, complicate assessments of supplements’ potential benefits and risks. Further, supplement manufacturers do not have to demonstrate safety or efficacy of their products, or get FDA approval for the claims, ingredient lists, or dosages on their labels, before they are marketed. All of these factors create a challenging environment for consumers to make informed decisions about their personal health.

What are supplements?

  • In the United States, a dietary supplement is defined by federal law as a product taken to supplement a person’s diet that contains one or more dietary ingredients and is intended to be taken by mouth, such as a pill, capsule, tablet, or liquid. Supplements are required by law to be labeled on their front panels as being a dietary supplement.
  • The dietary ingredients in supplement products can include vitamins, minerals, herbs, botanicals, and dietary fiber, among other substances.
  • Vitamins are sourced from animal or plant products or synthesized in a laboratory.
  • Minerals such as calcium, sodium, iron, and zinc are elements found in nature.
  • Both vitamins and minerals are required for the body to perform crucial tasks, including vision, bone growth, immune response, and wound healing.

How much is enough?

  • Dietary reference intakes (DRIs) are the recommended amounts of vitamins and minerals for people to consume daily. They are updated periodically by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine, an independent nonprofit that provides evidence-based advice on science, health, and engineering issues.
    • DRI values are different for individual nutrients and many of them vary widely based on age, sex, and whether a person is pregnant or lactating.
    • DRIs may inform regulations that govern food assistance programs at schools and elsewhere and provide a frame of reference for nutrition research and clinical practice.
  • Daily values are established by the FDA using DRIs. They lack DRIs’ specificity for age, gender, etc., but are recommended daily intakes of key ingredients for a typical diet.
  • Percent daily value is a metric found on the labels of packaged foods as well as supplements. For each nutrient, they reveal how much of a day’s requirement is in a single serving of that product.

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Creative Commons LicenseThe text and video on this page are licensed as Creative Commons CC BY-SA 4.0. Journalists are free to use any text or video on this page with or without attribution to SciLine.