Usually taken once per day, MVM's contain most or all of the recommended vitamins and minerals in a percentage specifically related to the Daily Value (DV), which is the amount of the nutrient you need each day. The Supplement Facts panel will show the %DV provided of each nutrient by one serving of the product. You may also want to check the serving size of the supplement, as occasionally a serving size may be more than one capsule or tablet! Read on if you are wondering if you should take one.
MVM's can't take the place of eating a variety of foods included in a healthy diet. Foods also have phytochemicals, antioxidants, protein, healthy fats, fiber and other ingredients with positive health effects. Most Americans consume all the nutrients needed through a balanced and varied diet of healthy food choices. The 2010 US Dietary Guidelines identified the following as nutrients of possible concern in American diets: vitamin B-12, vitamin D, folic acid, iron, calcium, potassium and fiber. A daily supplement may help ensure adequate intake of all but calcium, potassium and fiber (these are bulky nutrients, and will not easily fit into a MVM). People in certain life stage categories may also benefit from specific supplementation (infancy, pregnancy, breastfeeding or older adult).
Some who may benefit from vitamin/mineral supplements include:
- Vegetarians and vegans: This population should ensure adequate intake of vitamin B12, vitamin D, calcium, iron, and zinc, which are limited in plant foods.
- Pregnant women and women of child-bearing age who might become pregnant should get 400 mcg/day of folic acid from fortified foods and/or dietary supplements to reduce the risk of birth defects of the brain and spine in their newborn babies. Some women have problems absorbing adequate folate from food sources and need the pre-formed vitamin. A prenatal vitamin may contain folic acid and iron, as well as other important nutrients needed for mother and baby. Some nutrients may be harmful to babies, such as vitamin A, where too much can cause birth defects. A prenatal supplement contains part of the vitamin A as a precursor (beta carotene) and ensures that both mother and child are receiving healthy doses of all nutrients.
- In postmenopausal women, calcium and vitamin D supplements may increase bone density and reduce the risk of fractures. MVM's may not contain adequate amounts of these nutrients, so additional supplements may be needed.
- People over age 50 and menopausal or post-menopausal women should get recommended amounts of vitamin B12 from fortified foods and/or dietary supplements because they might not absorb enough of the B12 that is naturally found in food.
- Breastfed and partially breastfed infants should receive vitamin D supplements of 400 IU/day, as should non-breastfed infants who drink less than about 1 quart per day of vitamin D-fortified formula or milk. This would be a single vitamin supplement ordered by a physician.
- Those with a calorie-restricted diet (1,600 calories per day or less) may need a MVM, as a diet supplying less than 1,600 calories per day may not supply all of the necessary nutrients.
- Consult a medical professional regarding type and recommended amount of vitamin/mineral supplementation.
- Examine the Supplement Facts panel of all vitamin/mineral supplements you take, as well as fortified cereals and beverages you regularly consume (those that have added vitamins and minerals). Even some anti-immunity preparations may contain vitamins as part of the formula. You may be getting much more than you think from all sources. Make sure all important nutrients are contained in the product. Use the online DRI tool to make sure you are not exceeding upper safe limits for Dietary Reference Intakes (DRI's).
- Choose a MVM that contains no more than100% of the Daily Value (DV), rather than high potency supplements. Avoid those with large (mega) doses of any nutrient or that have other ingredients whose properties are unknown. For those without increased needs, take the MVM every other day for a more cost effective approach.
- Taking a MVM can raise the chances of getting too much of some nutrients, like iron, vitamin A, zinc, niacin, and folic acid, especially when a person uses more than a basic, once-daily product. Excess folic acid can mask B12 deficiency in older adults.
- For smokers and former smokers, avoid MVM's with large amounts of beta-carotene and vitamin A as studies link these with a higher risk of developing lung cancer.
- Adult men and postmenopausal women should avoid taking MVMs with 18 mg or more of iron unless their doctor has told them that they have iron deficiency. Also, remember that Iron supplements are a leading cause of poisoning in children under age 6, so keep any MVM's or iron tablets out of children's reach.
- If you take medicine to reduce blood clotting, talk to your health care provider before taking any MVM or dietary supplement with vitamin K. Vitamin K lowers the drug's effectiveness and doctors base the medicine dose partly on the amount of vitamin K you usually consume in foods and supplements.
- Office of Dietary Supplements Vitamin and Mineral Supplement Fact Sheet, Office of Dietary Supplements, National Institutes of Health.
- Dietary Supplements: Vitamins and Minerals, Colorado State University Extension, Fact Sheet No. 9.338, 9/2013.