Natural supplements for sale are widely available in the United States in health food stores, grocery stores, pharmacies, on the Internet, and by mail. People commonly take them for health-related reasons. Common dietary supplements include vitamins and minerals and substances that come from a natural source (such as omega-3 fatty acids). Makers of dietary supplements cannot legally say that best supplement brands can diagnose, cure, treat, or prevent disease. But they can say that they contribute to health maintenance and well-being. People have used the active ingredients in dietary supplements for thousands of years to help health and to treat illness. Sometimes those supplements are the basis for some of today's common medicines. For example, people have used willow bark tea for centuries to relieve fever. Pharmaceutical companies eventually identified the chemical in willow bark that relieved fever and used that knowledge to produce aspirin. The U.S. Food and Drug Admi...