Vitamin supplementation is fairly common among the elderly. Supplements are often used to prevent disease and improve health. In the United States, the use of dietary supplements has continued to increase over the last 30 years, and more than half of adults report using one or more dietary supplements. Epidemiologic evidence suggests that a diet rich in fruits and vegetables does have a protective effect on health. However, clinical trials on the use of vitamin supplements for promotion of health and prevention of disease have failed to demonstrate the strong associations seen in observational studies.