Dietary supplement users: demographics, product use, and medical system interaction

Dietary supplements-defined as vitamins and minerals, herbal products, tissue extracts, proteins and amino acids, and other products-are purchased to improve health and prevent disease. Little has been published, however, about the characteristics of either the products or the people who use them.

Consecutive customers visiting two health food stores during a 15-day period were interviewed by telephone. They were asked about their use of dietary supplements, demographics, and their use of the established health care system.

Of the 194 customers contacted, 136 (70.1 percent) completed the survey. Respondents took a total of 805 supplements, most often to prevent a health problem (84.3 percent). Herbal products were most commonly used. Garlic, ginseng, and Ginkgo biloba were the herbs most frequently used. Fifty products were found to have previously reported toxicities, including vitamin A, which 9 customers were taking in megadoses. Most customers were white (94.1 percent), female (75.7 percent), had at least 1 year of college education (70.6 percent), had health insurance (95.6 percent), and had a regular physician (85.3 percent).

Most of the dietary supplements consumed appear to be safe, but 50 of 805 had previously reported toxicities including megadoses of vitamin A. Garlic, ginseng, and Ginkgo biloba were the most commonly ingested herbs, and the medical literature supports their effectiveness for some conditions in humans. Customers of two health food stores had average to above-average education and took dietary supplements to stay healthy. They used the conventional health care system but did not typically consult their physician about dietary supplements. The pattern of use suggests that physicians might not be adequately addressing preventive and wellness issues in discussions with their patients. Furthermore, physicians might need to learn about dietary supplements so they can communicate with patients about them.