Using Dietary Supplements Wisely
Many people take dietary supplements in an effort to be well and stay healthy. With so many
dietary supplements available and so many claims made about their health benefits, how can a
consumer decide what's safe and effective? This fact sheet provides a general overview of dietary
supplements, discusses safety considerations, and suggests sources for additional information.
- Federal regulations for dietary supplements are very different from those for prescription and
over-the-counter drugs. For example, a dietary supplement manufacturer does not have to prove a product's
safety and effectiveness before it is marketed.
- If you are thinking about using a dietary supplement, first get information on it from reliable sources.
Keep in mind that dietary supplements may interact with medications or other dietary supplements and may
contain ingredients not listed on the label.
- Tell your health care providers about any complementary and alternative practices you use, including
dietary supplements. Give them a full picture of what you do to manage your health. This will help ensure
coordinated and safe care.
About Dietary Supplements
Dietary supplements were defined in a law passed by Congress in 1994 called the Dietary Supplement Health and
Education Act (DSHEA). According to DSHEA, a dietary supplement is a product that:
- Is intended to supplement the diet
- Contains one or more dietary ingredients (including vitamins, minerals, herbs or other botanicals, amino
acids, and certain other substances) or their constituents
- Is intended to be taken by mouth, in forms such as tablet, capsule, powder, softgel, gelcap, or liquid
- Is labeled as being a dietary supplement.
Herbal supplements are one type of dietary supplement. An herb is a plant or plant part (such as leaves,
flowers, or seeds) that is used for its flavor, scent, and/or therapeutic properties. "Botanical" is often used as
a synonym for "herb." An herbal supplement may contain a single herb or mixtures of herbs.
Research has shown that some uses of dietary supplements are effective in preventing or treating diseases. For
example, scientists have found that folic acid (a vitamin) prevents certain birth defects, and a regimen of
vitamins and zinc can slow the progression of the age- related eye disease macular degeneration. Also, calcium and
vitamin D supplements can be helpful in preventing and treating bone loss and osteoporosis (thinning of bone
Research has also produced some promising results suggesting that other dietary supplements may be helpful for
other health conditions (e.g., omega-3 fatty acids for coronary disease), but in
most cases, additional research is needed before firm conclusions can be drawn.
Dietary Supplement Use in the United States
A national survey conducted in 2007 found that 17.7 percent of American adults had used "natural products" (i.e.,
dietary supplements other than vitamins and minerals) in the past 12 months. The most popular products used by
adults for health reasons in the past 30 days were fish oil/omega 3/DHA (37.4%), glucosamine (19.9%), echinacea
(19.8%), flaxseed oil or pills (15.9%), and ginseng (14.1%). In another, earlier national survey covering all types
of dietary supplements, approximately 52 percent of adult respondents said they had used some type of supplement in
the last 30 days; the most commonly reported were multivitamins/multiminerals (35 percent), vitamins E and C (12-13
percent), calcium (10 percent), and B-complex vitamins (5 percent).
Federal Regulation of Dietary Supplements
The Federal Government regulates dietary supplements through the U.S. Food and Drug Administration (FDA). The
regulations for dietary supplements are not the same as those for prescription or over-the-counter drugs. In
general, the regulations for dietary supplements are less strict.
- A manufacturer does not have to prove the safety and effectiveness of a dietary supplement before it is
marketed. A manufacturer is permitted to say that a dietary supplement addresses a nutrient deficiency,
supports health, or is linked to a particular body function (e.g., immunity), if there is research to support
the claim. Such a claim must be followed by the words "This statement has not been evaluated by the Food and
Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease."
- Manufacturers are expected to follow certain "good manufacturing practices" (GMPs) to ensure that dietary
supplements are processed consistently and meet quality standards. Requirements for GMPs went into effect in
2008 for large manufacturers and are being phased in for small manufacturers through 2010.
- Once a dietary supplement is on the market, the FDA monitors safety. If it finds a product to be unsafe, it
can take action against the manufacturer and/or distributor, and may issue a warning or require that the
product be removed from the marketplace.
Also, once a dietary supplement is on the market, the FDA monitors product information, such as label claims and
package inserts. The Federal Trade Commission (FTC) is responsible for regulating product advertising; it requires
that all information be truthful and not misleading.
The Federal Government has taken legal action against a number of dietary supplement promoters or Web sites that
promote or sell dietary supplements because they have made false or deceptive statements about their products or
because marketed products have proven to be unsafe.
Sources of Science-Based Information
It's important to look for reliable sources of information on dietary supplements so you can evaluate the claims
that are made about them. The most reliable information on dietary supplements is based on the results of rigorous
To get reliable information on a particular dietary supplement:
- Ask your health care providers. Even if they do not know about a specific dietary supplement, they may be
able to access the latest medical guidance about its uses and risks.
- Look for scientific research findings on the dietary supplement. The National Center for Complementary and
Alternative Medicine (NCCAM) and the NIH Office of Dietary Supplements, as well as other Federal agencies, have
free publications, clearinghouses, and information on their Web sites.
If you are thinking about or are using a dietary supplement, here are some points to keep in mind.
Tell your health care providers about any complementary and alternative practices you use, including dietary
supplements. Give them a full picture of what you do to manage your health. This will help ensure coordinated and
safe care. (For tips about talking with your health care providers about CAM, see NCCAM's Time to Talk campaign at
nccam.nih.gov/timetotalk.) It is especially important to talk to your health care provider if you are
- Thinking about replacing your regular medication with one or more dietary supplements.
- Taking any medications (whether prescription or over-the-counter), as some dietary supplements have been
found to interact with medications.
- Planning to have surgery. Certain dietary supplements may increase the risk of bleeding or affect the
response to anesthesia.
- Pregnant or nursing a baby, or are considering giving a child a dietary supplement. Most dietary
supplements have not been tested in pregnant women, nursing mothers, or children.
If you are taking a dietary supplement, read the label instructions. Talk to your health care provider if you
have any questions, particularly about the best dosage for you to take. If you experience any side effects that
concern you, stop taking the dietary supplement, and contact your health care provider. You can also report your
experience to the FDA's MedWatch program. Consumer safety reports on dietary supplements are an important source of
information for the FDA.
Keep in mind that although many dietary supplements (and some prescription drugs) come from natural sources,
"natural" does not always mean "safe." For example, the herbs comfrey and kava can cause serious harm to the liver.
Also, a manufacturer's use of the term "standardized" (or "verified" or "certified") does not necessarily guarantee
product quality or consistency.
Be aware that an herbal supplement may contain dozens of compounds and that its active ingredients may not be
known. Researchers are studying many of these products in an effort to identify active ingredients and understand
their effects in the body. Also consider the possibility that what's on the label may not be what's in the bottle.
Analyses of dietary supplements sometimes find differences between labeled and actual ingredients. For example:
- An herbal supplement may not contain the correct plant species.
- The amount of the active ingredient may be lower or higher than the label states. That means you may be
taking less—or more—of the dietary supplement than you realize.
- The dietary supplement may be contaminated with other herbs, pesticides, or metals, or even adulterated
with unlabeled ingredients such as prescription drugs.
For current information from the Federal Government on the safety of particular dietary supplements, check the
"Dietary Supplements: Warnings and Safety Information" section of the FDA Web site at www.fda.gov/Food/DietarySupplements/Alerts/default.htm or
the "Alerts and Advisories" section of the NCCAM Web site at nccam.nih.gov/news/alerts.
Dietary Supplements Research at the National Institutes of Health
NCCAM, which is part of the National Institutes of Health (NIH), is the Federal Government's lead agency for
studying all types of CAM. As part of that role, the Center sponsors a wide array of research to see how dietary
supplements might affect the body and tests their use in clinical trials. In fiscal year 2007, NCCAM supported more
than 200 research projects studying dietary supplements, including herbs and botanicals.
Also within NIH, the Office of Dietary Supplements (ODS) focuses specifically on dietary supplements, seeking to
strengthen knowledge by supporting and evaluating research, disseminating results, and educating the public.
NCCAM and ODS collaborate to fund dietary supplement research centers focused on botanicals, known collectively as
the NIH Botanical Research Centers Program. Scientists at the centers conduct basic research and other studies on
botanicals and help to select products to be tested in clinical trials. The centers are advancing the scientific
base of knowledge about botanicals, making it possible to better evaluate their safety and effectiveness.
NCCAM also sponsors a number of Centers of Excellence for Research on CAM, including centers studying antioxidant
therapies, botanicals for autoimmune and inflammatory diseases, grape-derived polyphenols for Alzheimer's disease,
and botanicals for pancreatic diseases and for colorectal cancer.
- Barnes PM, Bloom B, Nahin R. Complementary
and alternative medicine use among adults and children: United States, 2007. CDC National Health Statistics Report #12. 2008.
- Dietary Supplement Health and Education Act
of 1994. U.S. Food and Drug Administration Web site. Accessed at http://www.fda.gov/RegulatoryInformation/Legislation/default.htm
on May 12,
- Dietary supplements: background information.
Office of Dietary Supplements Web site. Accessed at ods.od.nih.gov/factsheets/DietarySupplements_pf.asp on November 18,
- Dietary supplements: overview. U.S. Food and
Drug Administration, Center for Food Safety and Applied Nutrition Web site. Accessed at
www.fda.gov/Food/DietarySupplements/default.htm on May 12,
- Natural Medicines Comprehensive Database.
Product monographs. Accessed at www.naturaldatabase.com on May 13,
- Radimer K, Bindewald B, Hughes J, et
Dietary supplement use by US adults: data from the National Health
and Nutrition Examination Survey, 1999–2000. American Journal of