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.
Key
Points
- 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
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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 tissue).
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 scientific
testing.
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.
Safety
Considerations
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Jupiterimages
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.
Selected
References
- 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, 2008.
- Dietary supplements: background
information. Office of Dietary Supplements Web site.
Accessed at
ods.od.nih.gov/factsheets/DietarySupplements_pf.asp
on November 18,
2008.
- 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, 2008.
- Natural Medicines Comprehensive
Database. Product monographs. Accessed at
www.naturaldatabase.com on May 13, 2008.
- Radimer K, Bindewald B, Hughes J,
et al.
Dietary
supplement use by US adults: data from the National Health
and Nutrition Examination Survey,
1999–2000.
American Journal
of Epidemiology. 2004;160(4):339–349.
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