A dietary supplement is a product taken by mouth that contains a "dietary ingredient" intended to supplement the diet. The "dietary ingredients" in these products may include: vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites.Dietary supplements can also be extracts or concentrates, and may be found in many forms such as tablets, capsules, softgels, gelcaps, liquids, or powders. They can also be in other forms, such as a bar, but if they are, information on their label must not represent the product as a conventional food or a sole item of a meal or diet.

What are They For?

People use dietary supplements for many health conditions. People often use vitamins and minerals to supplement diet and treat disease. Historically, people have used herbal medicines to prevent illness, cure infection, reduce fever, and heal wounds. Herbal medicines can also treat constipation, ease pain, or act as relaxants or stimulants.

  Are They Safe?

Not all herbs and supplements are safe. If you are unsure about the safety of a supplement or herb, talk to your doctor or dietitian. Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medications or other supplements you might be taking. A side effect or interaction with another medication or supplement may make other health conditions worse.

The way dietary supplements are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of supplement that you buy in health food or grocery stores may not be the same as the form used in research. Other than for vitamins and minerals, the long-term effects of most dietary supplements are not known.