Issues in Nutrition: Dietary Supplements.

The majority of American adults report use of one or more dietary supplements every day or occasionally. The Dietary Supplement Health and Education Act of 1994 defines dietary supplements and regulates their manufacture and distribution. One of the most commonly used supplements is vitamin D. Measurement of serum levels of vitamin D must be undertaken with the caveats that different laboratories define normal levels differently, and that there is rarely a clinical correlation with the actual level. Patients should understand that supplements should not be used to excess, as there are toxicities and other adverse effects associated with most of them. There currently is considerable research being performed on probiotics and how the gut microbiome affects health and disease states. Protein supplements may be useful in reducing mortality rates in elderly patients but they do not appear to increase quality of life. If used, protein supplements should contain essential amino acids. Casein and whey supplements, derived from dairy sources, help transport essential amino acids to tissues. Although there have been many studies investigating the role of vitamin supplements in disease prevention, there have been few conclusive positive results.