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Multivitamin is the term applied to preparations intended to supplement the diet with vitamins, dietary minerals and other nutritional elements. Such preparations are available in the form of tablets, capsules, pastilles, powders, liquids and injectable formulations. Other than injectable formulations, which are only available and administered under medical supervision, multivitamins are recognised by the Codex Alimentarius Commission (the United Nations' highest authority on food standards) as a category of food. 
By supplementing the diet with additional vitamins and minerals, multivitamins can be a valuable tool for those with dietary imbalances or different nutritional needs . People with dietary imbalances may include those on restrictive diets and those who can't or won't eat a nutritious diet. Pregnant women and elderly adults have different nutritional needs than other adults, and a multivitamin may be indicated by their physicians.
Orthomolecular medicine proponents generally recommend individually optimized, often higher, vitamin intakes. They also recommend more absorbable forms of vitamins and minerals, in inexpensive but higher potency formulas, spread across the day. Iron-free formulas, and sometimes copper-free formulas, are sometimes preferred.
While multivitamins can be a valuable tool to correct dietary imbalances, it is worth exercising basic caution before taking them, especially if any medical conditions exist.
In particular, pregnant women should generally consult their doctors before taking any multivitamins. Because high doses of vitamin A are believed to cause birth defects, for example, special multivitamin formulations exist for pregnant women that do not contain this nutrient.
Severe vitamin and mineral deficiencies require medical treatment and can be very difficult to treat with common over-the-counter multivitamins. In such situations, special vitamin or mineral forms with much higher potencies are available, either as individual components or as specialized formulations, sometimes requiring a prescription.
Multivitamins may be dangerous if taken in large amounts, due to the toxicity of certain components, principally iron. In particular, other components at extraordinary levels in high potency forms include (but are not limited to) vitamin A, vitamin D, vitamin B6, time release niacin, and potassium. Total iron content of the whole bottle is the primary concern for child safety. There also are strict limits on the retinol content for vitamin A during pregnancies that are specifically addressed by prenatal formulas. Additionally, various medical conditions and medications may adversely interact with multivitamins.
For normal adults taking a multivitamin for general health purposes, conventional medicine and government authorities recommend that a multivitamin should contain 100% DRI or less for each ingredient. However, many common brand supplements in the United States contain above-DRI amounts for some vitamins or minerals. Many brands offer low iron or iron-free versions of their multivitamin supplements.
Recent research published in the Journal of the National Cancer Institute suggests that taking multivitamins more than seven times a week can increase the risk of advanced and fatal prostate cancer. Some analyses have suggested that beta-carotene, vitamin A and vitamin E supplements may shorten life rather than extend it. Other analyses, however, suggest that there appears to be little risk to supplement users of experiencing adverse side effects due to excessive intakes of micronutrients. 
Scientific evidence in favour of multivitamin supplements
In 2002, the Journal of the American Medical Association acknowledged that "it appears prudent for all adults to take vitamin supplements." In this article, which examined the clinical applications of vitamins for the prevention of chronic diseases in adults, the authors, Robert H. Fletcher and Kathleen M. Fairfield from the Harvard School of Medicine, examined English-language articles about vitamins in relation to chronic diseases published between 1966 and 2002, and concluded that inadequate intake of several vitamins has been linked to the development of diseases including coronary heart disease, cancer, and osteoporosis.  Similarly, the April 9, 1998 issue of the New England Journal of Medicine featured an editorial entitled "Eat Right and Take a Multivitamin" that was based on a succession of positive studies showing the disease-prevention benefits resulting from the consumption of nutritional supplements. 
Regulations by governmental agencies
The United States of America
Because of their categorization as a dietary supplement by the Food and Drug Administration (FDA), most multivitamins sold in the U.S. are not required to undergo the rigorous testing procedures typical of pharmaceutical drugs.
However, some multivitamins contain very high doses of one or several vitamins or minerals, or are specifically intended to treat, cure, or prevent disease, and therefore require a prescription or medicinal license in the U.S. Since such drugs contain no new substances, they do not require the same testing as would be required by a New Drug Application, but were allowed on the market as drugs due to the FDA's Drug Efficacy Study Implementation program. See 36 Fed. Reg. 6843 (Apr. 9, 1971).
Multivitamin product components
Basic commercial multivitamin supplement products often contain the following ingredients: vitamin C, B1, B2, B3, B6, folic acid (B9),B12, B5(pantothenate), H (biotin), A, E, D3, K1, potassium iodide, cupric (sulfate anhydrous, picolinate, sulfate monohydrate, trioxide), selenomethionine, borax, zinc, calcium, magnesium, chromium, manganese, molybdenum, betacarotene, and iron. Other formulas may include additional ingredients such as other carotenes (e.g. lutein, lycopene), higher than RDA amounts of B, C or E vitamins, "near" B vitamins (inositol, choline, PAPA), betaine hydrochloride, lecithin, citrus bioflavinoids or forms variously described as more easily absorbable.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Multivitamin". A list of authors is available in Wikipedia.|