Supplements in the U.S. are listed as ingredients intended to supplement a diet that may not contain enough of that particular vitamin, mineral, amino or fatty acid. They may not be listed as a cure. The Food and Drug Administration do not regulate these as drugs, they are considered foods. Many people seek supplements as diet aids to increase metabolism, or to affect mood, as in herbs that have calming effects, or to take away symptoms of different diseases like arthritis, as sleep aids, or as ways to improve memory or the immune system. Many supplements are not based on hard scientific research.
Because food supplements (also known as dietary supplements) are not drugs, they are much more loosely regulated in the United States.
For example, a company that is marketing a dietary supplement can essentially make any claim that they want about their product. They do not have to show the Food and Drug Administration any evidence to back up their claims.
The FDA website (http://www.fda.gov/Food/DietarySupplements/ConsumerInformation/ucm110417.htm#what) says
there is no provision under any law or regulation that FDA enforces that requires a firm to disclose to FDA or consumers the information they have about the safety or purported benefits of their dietary supplement products.
Food supplements are not medicines, they are intended to improve health problems. They can be used before or during medical treatments, during the period of physical or mental distressed condition, such as exams period of time. The food supplements serve memory, strengthens the immune system, bring a boost of vitamins and minerals, prevent atherosclerosis and kidney stones, etc.
Doctors, before starting drug therapy, recommend cures of this type of natural supplements.