A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet. Some countries define dietary supplements as foods, while in others they are defined as drugs or natural health products.
Supplements containing vitamins or dietary minerals are included as a category of food in the Codex Alimentarius, a collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. These texts are drawn up by the Codex Alimentarius Commission, an organization that is sponsored by the Food and Agriculture Organization (FAO) of the United Nations and the World Health Organization (WHO).
European Union 
The European Union's Food Supplements Directive of 2002 requires that supplements be demonstrated to be safe, both in dosages and in purity. Only those supplements that have been proven to be safe may be sold in the bloc without prescription. As a category of food, food supplements cannot be labeled with drug claims but can bear health claims and nutrition claims.
The dietary supplements industry in the United Kingdom (UK), one of the 27 countries in the bloc, strongly opposed the Directive. In addition, a large number of consumers throughout Europe, including over one million in the UK, and various doctors and scientists, had signed petitions by 2005 against what are viewed by the petitioners as unjustified restrictions of consumer choice. In 2004, along with two British trade associations, the Alliance for Natural Health had a legal challenge to the Food Supplements Directive referred to the European Court of Justice by the High Court in London. Although the European Court of Justice's Advocate General subsequently said that the bloc's plan to tighten rules on the sale of vitamins and food supplements should be scrapped, he was eventually overruled by the European Court, which decided that the measures in question were necessary and appropriate for the purpose of protecting public health. ANH, however, interpreted the ban as applying only to synthetically produced supplements—and not to vitamins and minerals normally found in or consumed as part of the diet. Nevertheless, the European judges did acknowledge the Advocate General's concerns, stating that there must be clear procedures to allow substances to be added to the permitted list based on scientific evidence. They also said that any refusal to add a product to the list must be open to challenge in the courts.
Studies have linked supplements, such as vitamins A and E, to various diseases and conditions, sometimes ones that they are supposed to prevent.
United States 
In the United States, a dietary supplement is defined under the Dietary Supplement Health and Education Act of 1994 (DSHEA) as a product that is intended to supplement the diet and contains any of the following dietary ingredients:
- a vitamin
- a mineral
- an herb or other botanical (excluding tobacco)
- an amino acid
- a concentrate, metabolite, constituent, extract, or combination of any of the above
- a substance historically used by humans to supplement the diet
Furthermore, it must also conform to the following criteria:
- intended for ingestion in pill, capsule, tablet, powder or liquid form
- not represented for use as a conventional food or as the sole item of a meal or diet
- labeled as a "dietary supplement"
Examples of dietary ingredients 
Because of the Dietary Supplement Health And Education Act of 1994 (DSHEA), the Food and Drug Administration (FDA) regulates dietary supplements as a category of foods, and not as drugs. While pharmaceutical companies are required to obtain FDA approval, which involves assessing the risks and benefits prior to their entry into the market, dietary supplements do not need to be pre-approved by FDA before they can enter the market. Instead, manufacturers and distributors who wish to market dietary supplements that contain a "new dietary ingredient" (defined as "a vitamin; a mineral; a herb or other botanical; an amino acid; a dietary substance for use by man to supplement the diet by increasing total dietary intake; or a concentrate, metabolite, constituent, extract, or combination of any of the above dietary ingredients" not marketed before October 15, 1994) must notify the FDA beforehand. The notification requires information indicating the ingredient is safe, and the ingredient can not be marketed (sold or delivered for sale) for seventy-five days following filing the information. During this time, the agency reviews the information for adequacy and safety concerns; fifteen days after this period (ninety days after the information was filed), the FDA posts nonproprietary information on their website. Listing the information means the ingredient can be marketed, but does not mean it is necessarily safe. On September 24, 2007 the FDA has implemented a "current good manufacturing practices" (GMP) policy to ensure dietary supplements "are produced in a quality manner, do not contain contaminants or impurities, and are accurately labeled" and covers the manufacturing, packaging, labelling, and storing of supplements, with requirements for quality control, design and construction of manufacturing plants, testing of ingredients and final products, record keeping, and complaints processes. And, in that same year, FDA implemented the “Dietary Supplement and Nonprescription Drug Consumer Protection Act” passed by Congress in 2006. This law established requirements for manufacturers to submit to the FDA reports of serious adverse events involving their products. These laws establishing requirements for GMP’s and adverse event reporting increased FDA’s oversight of dietary supplements.
However, in an April 25, 2012 presentation to the Natural Products Association (NPA), Dan Fabricant, Director of the FDA’s Dietary Supplements Program, called the level of non-compliance with cGMP’s “astonishing”. Based on audits completed by the FDA’s compliance division in 2011 and 2012, it was estimated that nearly 70% of dietary supplement manufacturers are currently not compliant with cGMP. Fabricant also indicated that FDA had concerns regarding under-reporting of adverse events.
The DSHEA, passed in 1994, was the subject of lobbying efforts by the manufacturers of dietary supplements and restricted the ability of the FDA to exert authority over supplements as long as manufacturers made no claims about their products treating, preventing, or curing diseases. According to Consumer Reports, "The law has left consumers without the protections surrounding the manufacture and marketing of over-the-counter or prescription medications" and it became the FDA's responsibility to prove that a supplement is not safe. While pharmaceutical manufacturers must demonstrate their products are effective as well as being safe, supplement manufacturers are not required to demonstrate efficacy. The FDA has ever found only one dietary supplement to be unsafe, the weight loss/energy supplement ephedra. Discussing the legislation, Time referred to the DSHEA as "ill-conceived and reprehensible", that "gives the industry virtually free reign [sic] to market products defined as dietary supplements, while severely limiting the FDA's ability to regulate them". The DSHEA was heavily lobbied for by the supplement industry, and was criticized for exposing the public to worthless compounds that bilked consumers out of money to no benefit. Because of the requirements put into place by the DSHEA, the FDA must demonstrate that individual supplements are unsafe using their adverse events reporting system, which is estimated to capture only 1 to 10 percent of all adverse events linked to supplements. The FDA has also lacked the funding to undertake the rigorous tests to meet the standards for a supplement to be considered "hazardous" and, thus, removed from the market; in the one situation where this standard was reached (ephedra), the agency faced significant opposition from the supplement industry and the United States Congress, instead limiting themselves to making announcements about problematic supplement safety records on their website.
A 2001 study, published in Archives of Internal Medicine, found broad public support for greater governmental regulation of dietary supplements than was currently permitted by DSHEA. The researchers found that a majority of Americans support pre-marketing approval by the FDA, increased oversight of harmful supplements, and greater scrutiny of the truthfulness of supplement label claims.
Under the FDA's final rule on good manufacturing practices, quality is defined as meaning "that the dietary supplement consistently meets the established specifications for identity, purity, strength, and composition and has been manufactured, packaged, labeled, and held under conditions to prevent adulteration under section 402(a)(1), (a)(2), (a)(3), and (a)(4) of the Federal Food, Drug, and Cosmetic Act". The new regulations allow FDA inspectors to look at a company's records upon request. However, enforcement is difficult given the number of supplement manufacturers and the 16% decline in FDA investigators from 2003 to 2006. Much of the contamination is due to poor raw ingredients. Suppliers provide certificates of analysis stating that they have tested the material. Under the 2003 proposed rule, manufacturers would have been required to retest the supplied ingredients. Under the final rule, testing for identity is always required. Other retesting is not required if the manufacturer has verified the reliability of the ingredient supplier.
In the U.S., contamination and false labeling are "not uncommon". Independent certification programs exist, but these may have problems as well. United States Pharmacopeia manages the Dietary Supplement Verification Program (DSVP). Its USP Verified Mark seal indicates that the product has been tested for integrity, purity, dissolution, and safe manufacturing, and it is the only certification program that conducts random off-the-shelf testing. The USP program will not certify products that contain ingredients that the USP's Dietary Supplement Information Expert Committee determines have a safety risk. ConsumerLab.com randomly tests some dietary supplements and makes the results available to subscribers. It has reported that 25% of the supplements it tests have problems, and for multivitamins about half had problems. In 2008 ConsumerLab criticized the USP for proposing a 10 microgram perdaily serving limit on lead in dietary supplements and drugs. It noted that under the FDA's 2006 guidance on lead in candy, only 0.2 micrograms of lead per serving are allowed. NSF International, HFL Sport Science, and the Natural Products Association (NPA) also have dietary supplement certification programs.
Permissible claims 
If a dietary supplement claims to cure, mitigate, or treat a disease, it would be considered an unauthorized new drug and in violation of the applicable regulations and statutes. As the FDA states, in a response to this question, in a FAQ:
Is it legal to market a dietary supplement product as a treatment or cure for a specific disease or condition?
No, a product sold as a dietary supplement and promoted on its label or in labeling* as a treatment, prevention or cure for a specific disease or condition would be considered an unapproved--and thus illegal--drug. To maintain the product's status as a dietary supplement, the label and labeling must be consistent with the provisions in the Dietary Supplement Health and Education Act (DSHEA) of 1994.
*Labeling refers to the label as well as accompanying material that is used by a manufacturer to promote and market a specific product.
The Act mandates that such products carry a warning in boldface type:
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
Companies that market dietary supplements are permitted to make structure/function claims about a given supplement in the marketing material. These are broad claims that the product can support the structure or function of the body (e.g., "glucosamine helps support healthy joints", "the hormone melatonin helps establish normal sleep patterns"). The FDA must be notified of these claims within 30 days of their first use, and there is a requirement that these claims be substantiated. In reality, misleading claims about supplements are common, in particular on poorly regulated commercial websites. For example, the compound hydrazine sulfate is sold as a dietary supplement in the USA and promoted as a treatment for cancer, despite little evidence that it is either safe or effective.
Other claims that require approval from FDA include health claims and qualified health claims. Health claims are permitted to be made if they meet the requirements for the claims found in the applicable regulations. Qualified health claims can be made through a petition process, including scientific information, if FDA has not approved a prior petition
Need for dietary supplements 
Most dietary supplements are unnecessary if one has a sufficiently healthy diet and the particular nutrients in these supplements are more easily absorbed by the body when they are eaten in the foods that naturally contain them. As such, only a small proportion of the total population has a real need for any supplement and then it is only those people who are unable to consume the food required to obtain the nutrient (such as those who are lactose intolerant taking a calcium supplement), despite the huge growth in the market.
Many such supplements have even been found to have no real effect, or at least not to have a large effect, particularly glucosamine and chondroitin which are taken to relieve joint pain. Relief reported for these supplements are confounded by the fact that many people taking them as recommended from a doctor are also taking other pain relievers. Another common supplement is omega-3 fatty acids which are naturally found in fatty fish, such as salmon, however no studies show that taking a supplement has any benefit for healthy individuals, so again only a small population has a need for this sort of addition to their diet. Some studies point out that dietary supplements can have harmful effects. The SELECT study, funded by the National Institute of Health, found that men who supplemented with 400UI/day of vitamin E had a higher rate of prostate cancer than men who did not. Also, it has been recently found that calcium supplementation puts people at a greater risk for heart attacks.
There may be several reasons why dietary supplements can harm. For those who take too many, or take too much, of a supplement—that taking more than the 100% recommended dose can pose health problems. This has the potential to lead to toxic effects as people get the vitamins or minerals present in these supplements from their diets already, particularly in the case of minerals and fat-soluble vitamins which can build up in the body. The other reasons why they can harm may be: a) absorption in a short time; b) quality and contaminations; and c) enhancing both positive and negative effects at the same time.
See also 
- Breast enlargement supplements
- Essential nutrient
- Food fortification
- Food processing
- Health freedom movement
- Medicinal mushrooms
- Megavitamin therapy
- Nutrients (journal)
- Nutritional genomics
- Nutrition Labeling and Education Act of 1990
- Orthomolecular medicine
- Snake oil
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- "Sleep Aids And Stimulants". MedicineNet.com. Retrieved 2008-06-25. "Melatonin is the only hormone available OTC for insomnia.... Melatonin is sold as a dietary supplement and is, therefore, not regulated by the FDA."
- Goldman, P. (2001). "Herbal medicines today and the roots of modern pharmacology". Annals of internal medicine 135 (8 Pt 1): 594–600. PMID 11601931.
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- NPA. Quality Assurance Programs
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- Questions and answers about hydrazine sulfate. National Cancer Institute. March 12, 2009.
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Further reading 
- Dietary Supplements: General Resources for Consumers (PDF|131 KB), Food and Nutrition Information Center, National Agricultural Library. List of resources that provides an overview of herbal and dietary supplements, including use, regulation, research, and cautionary information.
- Questions to Ask Before Taking Vitamin and Mineral Supplements, Nutrition.gov.
- Dietary Supplement Fact Sheets, NIH Office of Dietary Supplements.
- Dietary Supplements Labels Database, from the United States National Library of Medicine
- PubMed Dietary Supplement Subset from the U.S. National Institutes of Health Office of Dietary Supplements and United States National Library of Medicine
- Dietary Supplement Information from the U.S. Food and Drug Administration
- What's in the Bottle? An Introduction to Dietary Supplements, from the U.S. National Center for Complementary and Alternative Medicine
- Safety information on herbal supplements, from the U.S. National Institutes of Health
- Use of Complementary and Alternative Medicine (CAM) by the American Public: A report of the Institute of Medicine
- Marcus DM, Grollman AP (December 2002). "Botanical medicines--the need for new regulations". The New England Journal of Medicine 347 (25): 2073–6. doi:10.1056/NEJMsb022858. PMID 12490692.
- EPC Evidence Reports on Dietary Supplements