Echinacea to prevent colds. Ginkgo to improve memory. Flaxseed to lower cholesterol. The list of herbal remedies goes on and on.

Herbal supplements, sometimes called botanicals, are one type of dietary supplement available for purchase. Herbal supplements aren't new — plants have been used for medicinal purposes for thousands of years.

People commonly take them for health-related reasons. Common dietary supplements include vitamins and minerals (such as vitamin C or a multivitamin), botanicals (herbs and plant products, such as St. John's wort), and substances that come from a natural source (such as omega-3 fatty acids).

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.