Dietary supplement

Template:TOC-right Dietary supplements are supplements used to restore or maintain health when the diet does not meet the needs of an individual. In some cases, there is strong evidence for their use, although conventional foods, such as milk, may routinely be supplemented with, for example, vitamin D. Persons at risk for osteoporosis must be sure they have adequate calcium and vitamin D intake, with supplements as necessary.

Regulation

In many countries, there is considerable freedom to advertise substances as dietary supplements, as opposed to drugs. Substances marketed as dietary supplements, however, may not have undergone safety and efficacy testing.

Health policy considerations

While it is sufficiently widespread that it is not considered a dietary supplement, addition of fluoride ion to drinking water is common throughout the industrialized world. It was quite controversial when first proposed, but there is clear evidence of efficacy in preventing tooth decay. Adequate fluoride intake causes a higher concentration of more decay-resistant calcium fluoride in tooth enamel.

Some specific supplementation has been required by governments, although not always in a completely rational manner. For example, folic acid deficiency is strongly correlated with neural tube birth defects. There is general acceptance that all women, who might become pregnant, must ensure they have adequate folic acid intake. The U.S. requires that it be added to commercial baked goods, but, since woman does not live by bread alone, folic acid in uneaten bread benefits no one.

Although it is not standard practice, some researchers suggest widespread vitamin use may drastically cut public health spendings.

Vitamin supplements

There are recommended daily requirement (MDR) of many vitamins, but these are agreed to be minimum requirements. Mild supplementation, as, for example, a daily moderate-strength multivitamin, is widely accepted as potentially beneficial. A dose of a vitamin that greatly exceeds the MDR may be called a megadose, or a pharmacologic dose.

Moderate supplementation

As mentioned, there are some widely accepted reasons to supplement specific vitamins:

• Folic acid in women that may become pregnant
• Vitamin D in growing children, or for those at risk for osteoporosis

High-dose vitamins

Pharmacologic doses of vitamins are used in conventional medicine, but should be used with the care used for more mainstream drugs. Vitamins divide into two broad classes, water-soluble and fat-soluble; toxicity is much more likely with high doses of fat-soluble vitamins.

Water-soluble vitamins

Niacin

For example, niacin in pharmacologic doses can be an effective treatment for some dyslipedimias, or disorders of fat and cholesterol metabolism. It is available without a prescription. Such doses of niacin, however, have other physiologic effects. It is extremely common to experience skin flushing, which some patients regard as intolerable burning, shortly after taking a large oral dose of niacin. There are ways to reduce the flushing. Pharmacologic doses of niacin, however, also requires blood chemistry monitoring, as it can increase blood sugar levels, and rarely can damage cause hepatotoxicity (i.e., liver damages), muscle tissue breakdown (i.e., myolysis) or cause serious skin disease.

Fat-soluble vitamins

Vitamin A

Toxicity is most commonly found with high doses of Vitamin A. Indeed, certain cold-weather animals, such as the polar bear, concentrate such high levels in their liver that the meat is actually toxic to humans.

Hypervitaminosis A is not uncommon with overzealous parents giving babies large doses of prescribed A and D supplements.

Vitamin A deficiency (hypovitaminosis A) is a serious problem in the developing world.

Mineral supplementation

• osteoporosis
• trace elements

Other supplements

• chondroitin
• glucosamine