A dietary supplement is a manufactured product intended to supplement a person's diet in the form of a pill, capsule, tablet, powder, or liquid. A supplement can provide either extracted from food sources, or that are synthetic (to increase the quantity of their consumption). The classes of nutrient compounds in supplements include , Dietary mineral, Dietary fiber, , and . Dietary supplements can also contain substances that have not been confirmed as being essential to life, and so are not nutrients per se, but are marketed as having a beneficial biological effect, such as plant or . Animals can also be a source of supplement ingredients, such as collagen from chickens or fish for example. These are also sold individually and in combination, and may be combined with nutrient ingredients. The European Commission has also established harmonized rules to help insure that food supplements are safe and appropriately labeled.
Creating an industry estimated to have a value of $151.9 billion in 2021, there are more than 50,000 dietary supplement products marketed in the United States, where about 50% of the American adult population consumes dietary supplements. are the most commonly used product among types of dietary supplements. The United States National Institutes of Health states that some supplements may help provide essential nutrients or support overall health and performance for those with limited dietary variety.
In the United States, it is against federal regulations for supplement manufacturers to health claim that these products prevent or treat any disease. Companies are allowed to use what is referred to as "Structure/Function" wording if there is substantiation of scientific evidence for a supplement providing a potential health effect. An example would be "_____ helps maintain healthy joints", but the label must bear a disclaimer that the Food and Drug Administration (FDA) "has not evaluated the claim" and that the dietary supplement product is not intended to "diagnose, treat, cure or prevent any disease", because only a Medication can legally make such a claim. The FDA enforces these regulations and also prohibits the sale of supplements and supplement ingredients that are dangerous, or supplements not made according to standardized good manufacturing practices (GMPs).
Per DSHEA, dietary supplements are consumed orally, and are mainly defined by what they are not: conventional foods (including ), , or pharmaceutical drugs. Products intended for use as a nasal spray, or topically, as a lotion applied to the skin, do not qualify. FDA-approved drugs cannot be ingredients in dietary supplements. Supplement products are or contain vitamins, nutritionally essential minerals, , essential fatty acids and non-nutrient substances extracted from plants or animals or Fungus or bacteria, or in the instance of , are live bacteria. Dietary supplement ingredients may also be synthetic copies of naturally occurring substances (for example: melatonin). All products with these ingredients are required to be labeled as dietary supplements.
The U.S. Institute of Medicine sets tolerable upper intake levels (ULs) for some of the vitamins. This does not prevent dietary supplement companies from selling products with content per serving higher than the ULs. For example, the UL for vitamin D is 100 μg (4,000 IU), but products are available without prescription at 10,000 IU.
The essential nutrient minerals for humans, listed in order by weight needed to be at the Recommended Dietary Allowance or Adequate Intake are potassium, chlorine, sodium, calcium, phosphorus, magnesium, iron, zinc, manganese, copper, iodine, chromium, molybdenum, selenium and cobalt (the last as a component of vitamin B12). There are other minerals which are essential for some plants and animals, but may or may not be essential for humans, such as boron and silicon. Essential and purportedly essential minerals are marketed as dietary supplements, individually and in combination with vitamins and other minerals.
Although as a general rule, dietary supplement labeling and marketing are not allowed to make disease prevention or treatment claims, the U.S. FDA has for some foods and dietary supplements reviewed the science, concluded that there is significant scientific agreement, and published specifically worded allowed health claims. An initial ruling allowing a health claim for calcium dietary supplements and osteoporosis was later amended to include calcium supplements with or without vitamin D, effective January 1, 2010. Examples of allowed wording are shown below. To qualify for the calcium health claim, a dietary supplement must contain at least 20% of the Reference Dietary Intake, which for calcium means at least 260 mg/serving.
In the same year, the European Food Safety Authority also approved a dietary supplement health claim for calcium and vitamin D and the reduction of the risk of osteoporotic fractures by reducing bone loss.
The U.S. FDA also approved Qualified Health Claims (QHCs) for various health conditions for calcium, selenium and chromium picolinate. QHCs are supported by scientific evidence, but do not meet the more rigorous "significant scientific agreement" standard required for an authorized health claim. If dietary supplement companies choose to make such a claim then the FDA stipulates the exact wording of the QHC to be used on labels and in marketing materials. The wording can be onerous: "One study suggests that selenium intake may reduce the risk of bladder cancer in women. However, one smaller study showed no reduction in risk. Based on these studies, FDA concludes that it is highly uncertain that selenium supplements reduce the risk of bladder cancer in women."
According to US and Canadian Dietary Reference Intake guidelines, the protein Recommended Dietary Allowance (RDA) for adults is based on 0.8 grams protein per kilogram body weight. The recommendation is for sedentary and lightly active people. Scientific reviews can conclude that a high protein diet, when combined with exercise, will increase muscle mass and strength, or conclude the opposite. The International Olympic Committee recommends protein intake targets for both strength and endurance athletes at about 1.2–1.8 g/kg body mass per day. One review proposed a maximum daily protein intake of approximately 25% of energy requirements, i.e., approximately 2.0 to 2.5 g/kg.
The same protein ingredients marketed as dietary supplements can be incorporated into meal replacement and medical food products, but those are regulated and labeled differently from supplements. In the United States, "meal replacement" products are foods and are labeled as such. These typically contain protein, carbohydrates, fats, vitamins and minerals. There may be content claims such as "good source of protein", "low fat" or "lactose free". Medical foods, also nutritionally complete, are designed to be used while a person is under the care of a physician or other licensed healthcare professional. Liquid medical food products – for example, Ensure – are available in regular and high protein versions.
Proteins are chains of . Nine of these proteinogenic amino acids are considered essential for humans because they cannot be produced from other compounds by the human body and so must be taken in as food. Recommended intakes, expressed as milligrams per kilogram of body weight per day, have been established. Other amino acids may be conditionally essential for certain ages or medical conditions. Amino acids, individually and in combinations, are sold as dietary supplements. The claim for supplementing with the branched-chain amino acids leucine, valine and isoleucine is for stimulating muscle protein synthesis. A review of the literature concluded this claim was unwarranted. In elderly people, supplementation with just leucine resulted in a modest (0.99 kg) increase in lean body mass. The non-essential amino acid arginine, consumed in sufficient amounts, is thought to act as a donor for the synthesis of nitric oxide, a vasodilator. A review confirmed blood pressure lowering. Taurine, a popular dietary supplement ingredient with claims made for sports performance, is technically not an amino acid. It is synthesized in the body from the amino acid cysteine.
Plant oils, particularly seed and nut oils, contain ALA. Food sources of EPA and DHA are oceanic fish, whereas dietary supplement sources include fish oil, krill oil and marine algae extracts. The European Food Safety Authority (EFSA) identifies 250 mg/day for a combined total of EPA and DHA as Adequate Intake, with a recommendation that women pregnant or lactating consume an additional 100 to 200 mg/day of DHA. In the United States and Canada are for ALA and LA over various stages of life, but there are no intake levels specified for EPA and/or DHA.
Supplementation with EPA and/or DHA does not appear to affect the risk of death, cancer or heart disease. Furthermore, studies of fish oil supplements have failed to support claims of preventing heart attacks or strokes. In 2017, the American Heart Association issued a science advisory stating that it could not recommend use of omega-3 fish oil supplements for primary prevention of cardiovascular disease or stroke, although it reaffirmed supplementation for people who have a history of coronary heart disease.
Manufacturers have begun to include long chain polyunsaturated fatty acids DHA and arachidonic acid (AA) into their formula milk for newborns, however, a 2017 review found that supplementation with DHA and AA does not appear to be harmful or beneficial to formula-fed infants.
In 2019, sales of herbal supplements just in the United States alone were $9.6 billion, with the market growing at approximately 8.6% per year, with cannabidiol and mushroom product sales as the highest. Italy, Germany, and Eastern European countries were leading consumers of botanical supplements in 2016, with European Union market growth forecast to be $8.7 billion by 2020.
There is low quality and insufficient evidence for the use of oral antioxidant supplements as a viable treatment for subfertile woman. A review provided evidence that taking dehydroepiandrosterone before starting an in vitro fertilization series may increase pregnancy rates and decrease miscarriage likelihood.
Sufficient intake of vitamin B6 can lower the risk of early pregnancy loss and relieve symptoms of morning sickness. Folate is also an essential nutrient for pregnant women to prevent neural tube defects. In 2006, the World Health Organization endorsed the recommendation for women of child-bearing age to consume 400 of folate through the diet daily if planning a pregnancy. A 2013 review found folic acid supplementation during pregnancy did not affect the mother's health other than a risk reduction on low pre-delivery serum folate and megaloblastic anemia. There is little evidence to suggest that vitamin D supplementation improves prenatal outcomes in hypertensive disorders and gestational diabetes. Evidence does not support the routine use of vitamin E supplementation during pregnancy to prevent adverse events, such as preterm birth, fetal or neonatal death, or maternal hypertensive disorders.
Iron supplementation can lower the risk of iron deficiency anemia for pregnant women. In 2020, the World Health Organization updated recommendations for adequate calcium levels during pregnancy to prevent hypertensive disorders.
In some botanical products, undeclared ingredients were used to increase the bulk of the product and reduce its cost of manufacturing, while potentially violating certain religious and/or cultural limitations on consuming animal ingredients, such as cow, buffalo or deer. In 2015, the New York Attorney General (NY-AG) identified four major retailers with dietary supplement products that contained fraudulent and potentially dangerous ingredients, requiring the companies to remove the products from retail stores. According to the NY-AG, only about 20% of the herbal supplements tested contained the plants claimed. The methodology used by the NY-AG was disputed. The test involves looking for DNA fragments from the plants named as the dietary supplement ingredients in the products. One scientist said that it was possible that the extraction process used to create the supplements removed or destroyed all DNA. This, however, would not explain the presence of DNA from plants such as rice or wheat, that were not listed as ingredients.
A study of dietary supplements sold between 2007 and 2016 identified 776 that contained unlisted pharmaceutical drugs, many of which could interact with other medications and lead to hospitalization. 86% of the adulterated supplements were marketed for weight loss and sexual performance, with many containing prescription erectile dysfunction medication. Bodybuilding supplements were contaminated with that can lead to health complications affecting the kidney, the heart, and cause gynecomastia. Multiple bodybuilding products also contained and . Despite these findings, fewer than half of the adulterated supplements were recalled.
In the United States and Canada, dietary supplements are considered a subset of foods, and are regulated accordingly. The U.S. Food and Drug Administration (FDA) monitors supplement products for accuracy in advertising and labeling. Dietary supplements are regulated by the FDA as subject to compliance with current Good Manufacturing Practices (CGMP) and labeling with science-based ingredient descriptions and advertising. When finding CGMP or advertising violations, FDA warning letters are used to notify manufacturers of impending enforcement action, including search and seizure, injunction, and financial penalties. Examples between 2016 and 2018 of CGMP and advertising violations by dietary supplement manufacturers included several with illegal compositions or advertising of vitamins and minerals.
The U.S. Federal Trade Commission, which litigates against deceptive advertising in marketed products, established a consumer center to assist reports of false health claims in product advertising for dietary supplements. In 2017, the FTC successfully sued nine manufacturers for deceptive advertising of dietary supplements.
Among general reasons for the possible harmful effects of dietary supplements are: a) absorption in a short time, b) manufacturing quality and contamination, and c) enhancing both positive and negative effects at the same time. The incidence of hepatotoxicity from herbal and dietary supplements is about 16–20% of all supplement products causing injury, with the occurrence growing globally over the early 21st century. The most common liver injuries from weight loss and bodybuilding supplements involve Hepatocyte damage with resulting jaundice, and the most common supplement ingredients attributed to these injuries are green tea , , and the herbal extract, Aegle marmelos. Weight loss supplements have also had adverse psychiatry. Some dietary supplements may also have adverse interactions with prescription medications that may enhance side effects or decrease therapeutic effects of medications.
For example, while increased consumption of fruits and vegetables are related to decreases in mortality, cardiovascular diseases and cancers, supplementation with key factors found in fruits and vegetable, like antioxidants, vitamins, or minerals, do not help and some have been found to be harmful in some cases. In general, as of 2016, robust clinical data is lacking, that shows that any kind of dietary supplementation does more good than harm for people who are healthy and eating a reasonable diet but there is clear data showing that dietary pattern and lifestyle choices are associated with health outcomes.
As a result of the lack of good data for supplementation and the strong data for dietary pattern, public health recommendations for healthy eating urge people to eat a plant-based diet of whole foods, minimizing ultra-processed food, salt and sugar and to get exercise daily, and to abandon Western pattern diets and a sedentary lifestyle.
Substances which the FDA regulates as food are subdivided into various categories, including foods, , added substances (man-made substances which are not intentionally introduced into food, but nevertheless end up in it), and dietary supplements. The specific standards which the FDA exercises differ from one category to the next. Furthermore, the FDA has been granted a variety of means by which it can address violations of the standards for a given category of substances.
Dietary supplement manufacture is required to comply with the good manufacturing practices established in 2007. The FDA can visit manufacturing facilities, send Warning Letters if not in compliance with GMPs, stop production, and if there is a health risk, require that the company conduct a recall. Only after a dietary supplement product is marketed, may the FDA's Center for Food Safety and Applied Nutrition (CFSAN) review the products for safety and effectiveness.
The dietary supplements industry in the United Kingdom (UK), one of the 28 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 (ANH) 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 acknowledged 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 the product to the list must be open to challenge in the courts.
In 2015, the Australian Government's Department of Health published the results of a review of herbal supplements to determine if any were suitable for coverage by health insurance. Establishing guidelines to assess safety and efficacy of botanical supplement products, the European Medicines Agency provided criteria for evaluating and grading the quality of clinical research in preparing monographs about herbal supplements. In the United States, the National Center for Complementary and Integrative Health of the National Institutes of Health provides fact sheets evaluating the safety, potential effectiveness and side effects of many botanical products.
A 2017 academic review indicated a rising incidence of liver injury from use of herbal and dietary supplements, particularly those with , green tea extract, or multiple ingredients.
Definition
Types
Vitamins
Minerals
Proteins and amino acids
Bodybuilding supplements
Beauty supplements
Essential fatty acids
Natural products
Probiotics
Fertility
Prenatal
Pharmacotherapy
Industry
Adulteration, contamination and mislabeling
Regulatory compliance
Adverse effects
Society and culture
Public health
Legal regulation
United States
European Union
Fraudulent products during the COVID-19 outbreak
Research
Databases
Quality and safety
Population monitoring
Clinical studies
Absence of benefit
Reporting bias
Future
See also
Further reading
External links
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