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Get the Facts
What's in the Bottle? An Introduction to Dietary Supplements

February 2007


Introduction

Dietary supplements are a topic of great public interest. Whether you are in a store, using the Internet, or talking to people you know, you may hear about supplements and claims of benefits for health. How do you find out whether "what's in the bottle" is safe to take, and whether science has proven that the product does what it claims? This fact sheet provides some answers. To find out more about topics and resources mentioned in this fact sheet, see "For More Information."


Questions and Answers

  1. What are dietary supplements?
  2. Why do people take supplements?
  3. Is using supplements considered conventional medicine or complementary and alternative medicine (CAM)?
  4. How can I get science-based information on a supplement?
  5. If I am interested in using a supplement as CAM, how can I do so most safely?
  6. I see the word "natural" on a lot of supplement labels. Does "natural" always mean "safe"?
  7. Does the Federal Government regulate supplements?
  8. Is NCCAM supporting research on supplements?

1. What are dietary supplements?

Dietary supplements (also called nutritional supplements, or supplements for short) were defined in a law passed by Congress in 1994 (see the box below).1, 2

About Dietary Supplements

A dietary supplement must meet all of the following conditions:

  • It is a product (other than tobacco) that is intended to supplement the diet and that contains one or more of the following: vitamins, minerals, *herbs or other botanicals, amino acids, or any combination of the above ingredients.
  • It is intended to be taken in tablet, capsule, powder, softgel, gelcap, or liquid form.
  • It is not represented for use as a conventional food or as a sole item of a meal or the diet.
  • It is labeled as being a dietary supplement.
  • * Linked terms are defined at the end of this fact sheet.

Dietary supplements are sold in grocery, health food, drug, and discount stores, as well as through mail-order catalogs, TV programs, the Internet, and direct sales.

2. Why do people take supplements?

People take supplements for many reasons. A scientific study on this topic was published in 2002.3 In it, over 2,500 Americans reported on supplements they used (given the categories of vitamins/minerals and herbal products/natural supplements) and for what reasons. Their responses are summarized in the table below.

Supplements: Why Taken?

Vitamins/ Minerals% of ResponsesHerbals/ Supplements% of Responses
Health/ good for you35Health/ good for you16
Dietary supplement11Arthritis7
Vitamin/mineral supplement8Memory improvement6
Prevent osteoporosis6Energy5
Physician recommended6Immune booster5
Prevent colds/influenza3Joint4
Don't know/ no reason specified3Supplement diet4
Immune booster2Sleep aid3
Recommended by friend/ family/ media2Prostate3
Energy2Don't know/ no reason specified2
All others22All others45

3. Is using supplements considered conventional medicine or complementary and alternative medicine (CAM)?

Some uses of dietary supplements have become part of conventional medicine (see box below). For example, scientists have found that the vitamin folic acid prevents certain birth defects, and a regimen of vitamins and zinc can slow the progression of the eye disease age-related macular degeneration.

On the other hand, some supplements are considered to be CAM--either the supplement itself or one or more of its uses. An example of a CAM supplement would be an herbal formula that claims to relieve arthritis pain, but has not been proven to do so through scientific studies. An example of a CAM use of a supplement would be taking 1,000 milligrams of vitamin C per day to prevent or treat a cold, as the use of large amounts of vitamin C for these purposes has not been proven.

Conventional Medicine

Conventional medicine is medicine as practiced by holders of M.D. (medical doctor) or D.O. (doctor of osteopathy) degrees and by their allied health professionals, such as physical therapists, psychologists, and registered nurses. Other terms for conventional medicine include allopathy; Western, mainstream, orthodox, and regular medicine; and biomedicine.

Complementary and Alternative Medicine (CAM)

CAM is a group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine. Complementary medicine is used together with conventional medicine, and alternative medicine is used in place of conventional medicine. Some health care providers practice both CAM and conventional medicine. There is scientific evidence for the effectiveness of some CAM treatments. But for most, there are key questions yet to be answered through well-designed scientific studies, such as whether they are safe and work for the diseases or conditions for which they are used. The National Center for Complementary and Alternative Medicine (NCCAM), part of the National Institutes of Health (NIH), is the Federal Government's lead agency for scientific research on CAM.

4. How can I get science-based information on a supplement?

There are several ways to get information on supplements that is based on the results of rigorous scientific testing, rather than on testimonials and other unscientific information.

5. If I am interested in using a supplement as CAM, how can I do so most safely?

Here are some points to keep in mind:

Supplements and Drugs Can Interact

  • St. John's wort can increase the effects of prescription drugs used to treat depression. It can also interfere with drugs used to treat HIV infection, to treat cancer, for birth control, or to prevent the body from rejecting transplanted organs.5
  • Ginseng can increase the stimulant effects of caffeine (as in coffee, tea, and cola). It can also lower blood sugar levels, creating the possibility of problems when used with diabetes drugs.5
  • Ginkgo, taken with anticoagulant or antiplatelet drugs, can increase the risk of bleeding. It is also possible that ginkgo might interact with certain psychiatric drugs and with certain drugs that affect blood sugar levels.5

6. I see the word "natural" on a lot of supplement labels. Does "natural" always mean "safe"?

There are many supplements, as well as many prescription drugs, that come from natural sources and are both useful and safe. However, "natural" does not always mean "safe" or "without harmful effects." For example, consider mushrooms that grow in the wild--some are safe to eat, while others are poisonous.

The FDA issues warnings about supplements that pose risks to consumers, including those used for CAM therapies. A sample list is in the box below6,7. The FDA found these products of concern because they:

Examples of Supplements That Have Carried FDA Cautions About Safety

  • Ephedra
  • Kava
  • Some "dieter's teas"
  • L-tryptophan
  • PC SPES and SPES
  • Aristolochic acid
  • Comfrey
  • St. John's wort
  • GHB (gamma hydroxybutyric acid), GBL (gamma butyrolactone), and BD (1,4-butanediol)

  • Certain products, marketed for sexual enhancement and claimed to be "natural" versions of the drug Viagra, which were found to contain an unlabeled drug (sildenafil or tadalafil)

7. Does the Federal Government regulate supplements?

Yes, the Federal Government regulates supplements through the FDA. Currently, the FDA regulates supplements as foods rather than drugs. In general, the laws about putting foods (including supplements) on the market and keeping them on the market are less strict than the laws for drugs. Specifically:

In March 2003, the FDA published proposed guidelines for supplements that would require manufacturers to avoid contaminating their products with other herbs, pesticides, heavy metals, or prescription drugs. The guidelines would also require supplement labels to be accurate.

The Federal Government also regulates supplement advertising, through the Federal Trade Commission. It requires that all information about supplements be truthful and not mislead consumers.

What's in the Bottle Does Not Always Match What's on the Label

A supplement might:

  • Not contain the correct ingredient (plant species). For example, one study that analyzed 59 preparations of echinacea found that about half did not contain the species listed on the label.8
  • Contain higher or lower amounts of the active ingredient. For example, an NCCAM-funded study of ginseng products found that most contained less than half the amount of ginseng listed on their labels.9
  • Be contaminated.

8. Is NCCAM supporting research on supplements?

Yes, NCCAM is funding most of the nation's current research aimed at increasing scientific knowledge about supplements--including whether they work; if so, how they work; and how purer and more standardized products could be developed. Among the substances that researchers are studying are:

Recent NCCAM-sponsored or cosponsored clinical trials include:


For More Information

NCCAM Clearinghouse

The NCCAM Clearinghouse provides information on CAM and NCCAM, including publications and searches of Federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.

Toll-free in the U.S.: 1-888-644-6226
TTY (for deaf and hard-of-hearing callers): 1-866-464-3615
Web site: nccam.nih.gov
E-mail: info@nccam.nih.gov

U.S. Food and Drug Administration (FDA)

The FDA oversees the safety of many products, such as foods (including dietary supplements), medicines, medical devices, and cosmetics.

Web site: fda.gov
Toll-free in the U.S.: 1-888-463-6332

Center for Food Safety and Applied Nutrition (CFSAN)

CFSAN oversees the safety and labeling of supplements, foods, and cosmetics. Publications include "Tips for the Savvy Supplement User: Making Informed Decisions and Evaluating Information."

Web site: cfsan.fda.gov
Toll-free in the U.S.: 1-888-723-3366

MedWatch

MedWatch, the FDA's safety information and adverse event reporting program, allows consumers and health care providers to file reports on serious problems suspected with dietary supplements.

Web site: fda.gov/medwatch/report/consumer/consumer.htm
Toll-free in the U.S.: 1-888-463-6332

Federal Trade Commission (FTC)

The FTC is the Federal agency charged with protecting the public against unfair and deceptive business practices. A key area of its work is the regulation of advertising (except for prescription drugs and medical devices).

Web site: ftc.gov
Toll-free in the U.S.: 1-877-382-4357

Office of Dietary Supplements (ODS), NIH

ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public. Its resources include publications and the International Bibliographic Information on Dietary Supplements (IBIDS) database.

Web site: ods.od.nih.gov
E-mail: ods@nih.gov

PubMed®

A service of the National Library of Medicine (NLM), PubMed contains publication information and (in most cases) brief summaries of articles from scientific and medical journals. CAM on PubMed, developed jointly by NCCAM and NLM, is a subset of the PubMed system and focuses on the topic of CAM.

Web site: ncbi.nlm.nih.gov/entrez
CAM on PubMed: nccam.nih.gov/camonpubmed/

The Cochrane Database of Systematic Reviews

The Cochrane Database of Systematic Reviews is a collection of evidence-based reviews produced by the Cochrane Library, an international nonprofit organization. The reviews summarize the results of clinical trials on health care interventions. Summaries are free; full-text reviews are by subscription only.

Web site: www.cochrane.org/reviews


References

  1. Dietary Supplement Health and Education Act of 1994. Food and Drug Administration Web site. Accessed at fda.gov/opacom/laws/dshea.html on April 14, 2003.
  2. Dietary supplements: overview. U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition Web site. Accessed at cfsan.fda.gov/~dms/supplmnt.html on August 20, 2003.
  3. Kaufman DW, Kelly JP, Rosenberg L, et al. Recent patterns of medication use in the ambulatory adult population of the United States: the Slone survey. Journal of the American Medical Association. 2002;287(3):337-344.
  4. Federal Trade Commission. Promotions for kids' dietary supplements leave sour taste. Federal Trade Commission Web site. Accessed at ftc.gov/opa/2004/06/kidsupp.htm on May 2, 2003.
  5. Natural Medicines Comprehensive Database. Natural Medicines Comprehensive Database Web site. Accessed on August 20, 2003.
  6. MedWatch: the FDA safety information and adverse event reporting program. U.S. Food and Drug Administration Web site. Accessed at fda.gov/medwatch on August 20, 2003.
  7. Dietary supplements: warnings and safety information. U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition Web site. Accessed at cfsan.fda.gov/~dms/ds-warn.html on April 14, 2003.
  8. Gilroy CM, Steiner JF, Byers T, et al. Echinacea and truth in labeling. Archives of Internal Medicine. 2003;163(6):699-704.
  9. Harkey MR, Henderson GL, Gershwin ME, et al. Variability in commercial ginseng products: an analysis of 25 preparations. American Journal of Clinical Nutrition. 2001;73(6):1101-1106.




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