Vitamins and Minerals
Vitamins and Minerals
Vitamins and minerals are essential substances that our bodies need to develop and function normally. The known vitamins include A, C, D, E, and K, and the B vitamins: thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxal (B6), cobalamin (B12), biotin, and folate/folic acid. A number of minerals are essential for health: calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, sulfur, cobalt, copper, fluoride, manganese, and selenium. The Dietary Guidelines for Americans 2015–2020 recommends that people should aim to meet their nutrient requirements through a healthy eating pattern that includes nutrient-dense forms of foods.
Multivitamins/multiminerals (MVMs) are the most frequently used dietary supplements, with close to half of American adults taking them. MVMs cannot take the place of eating a variety of foods that are important to a healthy diet. Foods provide more than vitamins and minerals. Many foods also have fiber and other substances that can provide health benefits. However, some people who don’t get enough vitamins and minerals from food alone, or who have certain medical conditions, might benefit from taking one or more of these nutrients found in single-nutrient supplements or in MVMs. However, evidence to support their use for overall health or disease prevention in the general population remains limited.
- Taking a daily dose of a basic MVM is unlikely to pose a health risk for most people. However, if you consume fortified foods and beverages (such as cereals or drinks with added vitamins and minerals) along with dietary supplements, you should make sure that your total intake of vitamins and minerals is not more than the safe upper limits for any nutrients. Read the Nutrition Facts label on packaged foods or the Supplement Facts label of MVMs to see if the level far exceeds 100% DV. For more information on safe upper levels of nutrients, visit the NIH Office of Dietary Supplements at: ods.od.nih.gov/factsheets/list-all.
- Smokers, and possibly former smokers, should avoid MVM products that provide more than 100% DV for vitamin A (either as preformed retinol or beta-carotene or some combination of the two) because two studies have linked high supplemental doses of these nutrients with an increased risk of lung cancer in smokers.
- Taking excess amounts of vitamin A (preformed retinol form, not as beta-carotene) during pregnancy has been shown to increase the risk of birth defects.
- Except in cases of iron deficiency or inadequacy, or unless a physician recommends otherwise, adult males and postmenopausal women should avoid using iron supplements or MVMs containing more than their recommended daily allowance for iron (8 mg/day). Iron supplements may be recommended for women of childbearing age, pregnant women, preterm infants, older infants, and teenage girls because they are at greater risk of developing deficiency. Yet, iron supplements are a leading cause of poisoning in young children, so parents and guardians should keep iron-containing supplements out of the reach of children.
- MVMs providing nutrients at or up to 100% DV do not typically interact with medications. However, if you take a blood thinner, such as warfarin (Coumadin and other brand names), talk to your health care provider before taking any MVM or dietary supplement that contains vitamin K (this vitamin lowers the medicine’s effectiveness, and doctors base the medicine’s dose partly on the overall amount of vitamin K a person usually consumes in foods and supplements).
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