What are Vitamins?
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.
How are Vitamins Consumed?
Most individuals can get all of the necessary vitamins and minerals through a healthy eating pattern of nutrient-dense foods. Multivitamins/multiminerals (MVMs) are the most frequently used dietary supplements, with close to half of American adults taking them. Taking an MVM increases overall nutrient intake and helps some people get the recommended amounts of vitamins and minerals when they can’t or don’t get them from food alone. But taking an MVM can also raise the chances of getting too much of some nutrients, like iron, vitamin A, zinc, niacin, and folate/folic acid, especially when a person takes more than a basic, once-daily product that provides 100 percent of the daily value (DV) of nutrients.
Do Vitamins Pose Health Risks?
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.
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.
There’s no standard or regulatory definition for MVMs, or any dietary supplement, as to what nutrients they must contain or at what levels. Manufacturers choose which vitamins, minerals, and other ingredients, as well as their amounts, to include in their products. Simply stated, dietary supplements aren’t required to be standardized in the United States. However, they are required to bear a Supplement Facts label and ingredient list describing what’s in the product.