What are dietary supplements?
In the United States, dietary supplements are substances you eat or
drink. They can be vitamins, minerals, herbs or other plants,
amino acids (the individual building blocks of
protein), or parts of these substances. They can be in pill, capsule, tablet,
or liquid form. They supplement (add to) the diet and should not be considered
a substitute for food.
Dietary supplements 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 (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 glucosamine).
Makers of dietary supplements cannot legally say that dietary
supplements can diagnose, cure, treat, or prevent disease. But they can say
that they contribute to health maintenance and well-being.
People have used 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 control fever. Pharmaceutical companies eventually identified the
chemical in willow bark that reduces fever and used that knowledge to produce
aspirin.
The U.S. Food and Drug Administration (FDA) does not regulate
dietary supplements in the same way that it regulates medicine. A dietary
supplement can be sold without research on how well it works.
What are dietary supplements used for?
People use dietary supplements for many health conditions.
- People often use vitamins and minerals to
supplement diet and treat disease. For example, echinacea may keep you from
getting a cold and may help you get better faster.1
High doses of vitamin C may also help you get better faster.
-
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. Research on some
herbs and plant products has shown that they may have some of the same effects
that conventional medicines do, while others may have no effect or may be
harmful.
- Researchers have studied some natural products and have found
them to be useful. Glucosamine, for example, is often used in the treatment of
osteoarthritis.
Are dietary supplements 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 dietician.
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. It may not be safe to forgo your conventional medical
treatment and rely only on a dietary supplement. This is especially important
for women who are pregnant or breast-feeding.
When using dietary supplements, keep in mind the following.
- Like conventional medicines, dietary
supplements may cause side effects, trigger allergic reactions, or interact
with prescription and nonprescription medicines or other supplements you might
be taking. A side effect or interaction with another medicine 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.
