Informationen über Nahrungsergänzungsmittel

Ein Nahrungsergänzungsmittel ist ein hergestelltes Produkt, das dazu gedacht ist, die Ernährung einer Person in Form einer Pille, Kapsel, Tablette, Pulver oder Flüssigkeit zu ergänzen. ^[2] Ein Nahrungsergänzungsmittel kann Nährstoffe liefern, die entweder aus Nahrungsquellen extrahiert oder synthetisiert werden (um die Menge zu erhöhen). Die Klassen der Nährstoffverbindungen in Nahrungsergänzungsmitteln umfassen Vitamine, Mineralstoffe, Ballaststoffe, Fettsäuren und Aminosäuren. Nahrungsergänzungsmittel können auch Substanzen enthalten, die nicht als lebensnotwendig bestätigt wurden, wie Pflanzenpigmente oder Polyphenole, und sind daher per Definition nicht unbedingt Nährstoffe. Sie können jedoch weiterhin als positiv biologisch wirksam vermarktet werden. Tiere können auch eine Quelle von Nahrungsergänzungsmitteln sein; Zum Beispiel kann Kollagen aus Hühnern oder Fischen extrahiert werden. Nahrungsergänzungsmittel werden in mehreren Dosen verkauft, von einmaliger Anwendung bis hin zu ganzen Gängen. Sie können auch mit nährstoffreichen Inhaltsstoffen angereichert werden.

In den Vereinigten Staaten wurde die Nahrungsergänzungsmittelbranche im Jahr 2021 auf einen Wert von 151,9 Milliarden US-Dollar geschätzt. ^[3] In den Vereinigten Staaten werden mehr als 95.000 Nahrungsergänzungsmittel vermarktet, und etwa 60 % der erwachsenen amerikanischen Bevölkerung konsumieren Nahrungsergänzungsmittel, 74 % bei Amerikanern über 60 Jahren. ^{[4]: 30} Multivitamine sind das am häufigsten verwendete Produkt unter den Arten von Nahrungsergänzungsmitteln. ^[5] Die National Institutes of Health der Vereinigten Staaten (NIH) gibt an, dass einige Nahrungsergänzungsmittel dazu beitragen können, essentielle Nährstoffe bereitzustellen oder die allgemeine Gesundheit und Leistung für Menschen mit begrenzter Ernährungsvielfalt zu unterstützen. ^[6]

In den Vereinigten Staaten verstößt es gegen Bundesvorschriften, wenn Hersteller von Nahrungsergänzungsmitteln behaupten, ihre Produkte würden Krankheiten verhindern oder behandeln. Unternehmen dürfen die sogenannte "Struktur/Funktion"-Formulierung verwenden, wenn wissenschaftliche Belege für ein Nahrungsergänzungsmittel mit potenziellen gesundheitlichen Auswirkungen vorliegen. ^[7] Ein Beispiel wäre "_____ hilft, gesunde Gelenke zu erhalten", aber auf dem Etikett muss ein Hinweis darauf verweisen, dass die Food and Drug Administration (FDA) "die Behauptung nicht bewertet hat" und dass das Nahrungsergänzungsprodukt nicht dazu gedacht ist, "eine Krankheit zu diagnostizieren, zu behandeln, zu heilen oder zu verhindern", da nur ein Medikament eine solche Behauptung rechtlich aufstellen kann. ^[7] Die FDA setzt diese Vorschriften durch und verbietet zudem den Verkauf von Nahrungsergänzungsmitteln und Nahrungsergänzungsmitteln, die gefährlich sind, oder von Nahrungsergänzungsmitteln, die nicht nach standardisierten guten Herstellungspraktiken (GMPs) hergestellt werden.

Die Europäische Kommission hat harmonisierte Regeln festgelegt, um sicherzustellen, dass Nahrungsergänzungsmittel in der Europäischen Union sicher und angemessen gekennzeichnet sind. ^[8]

Laut US-Gesetzgebung entschied der Dietary Supplement Health and Education Act von 1994 folgende Definition von Nahrungsergänzungsmitteln: "Der Dietary Supplement Health and Education Act von 1994 (DSHEA) definiert den Begriff "Nahrungsergänzungsmittel" als ein Produkt ... Sie soll die Ernährung ergänzen, die einen oder mehrere der folgenden Zutaten enthält oder enthält: ein Vitamin, ein Mineralstoff, ein Kraut oder ein anderes botanisches Mittel, eine Aminosäure, eine vom Menschen verwendete Substanz zur Ergänzung der Gesamtnahrungsaufnahme oder ein Konzentrat, Metabolit, Bestandteil, Extrakt oder Kombination einer der genannten Zutaten. Darüber hinaus muss ein Nahrungsergänzungsmittel als Nahrungsergänzungsmittel gekennzeichnet und für die Einnahme bestimmt sein und darf nicht als konventionelles Lebensmittel oder als alleiniges Nahrungsmittel oder Nahrungsmittel dargestellt werden. Außerdem kann ein Nahrungsergänzungsmittel nicht als neues Medikament, Antibiotikum oder Biologika zugelassen oder zugelassen werden, es sei denn, es wurde vor der Zulassung als Lebensmittel oder Nahrungsergänzungsmittel vermarktet. Nach DSHEA gelten Nahrungsergänzungsmittel als Lebensmittel, außer für die Zwecke der Arzneimitteldefinition." ^[9]

Laut DSHEA werden Nahrungsergänzungsmittel oral eingenommen und werden hauptsächlich dadurch definiert, was sie nicht sind: herkömmliche Lebensmittel (einschließlich Mahlzeitenersatz), medizinische Lebensmittel,^[10] Konservierungsstoffe oder pharmazeutische Medikamente. Produkte, die als Nasenspray oder topische Anwendung gedacht sind, wie etwa eine Lotion auf die Haut, qualifizieren nicht. FDA-zugelassene Medikamente dürfen nicht als Inhaltsstoffe in Nahrungsergänzungsmitteln verwendet werden. Nahrungsergänzungsprodukte sind oder enthalten Vitamine, ernährungsphysiologisch wichtige Mineralstoffe, Aminosäuren, essentielle Fettsäuren, nicht-nährstoffreiche Substanzen, die aus Pflanzen, Tieren, Pilzen oder Bakterien gewonnen werden, und im Fall von Probiotika lebende Mikroorganismen. Zutaten von Nahrungsergänzungsmitteln können auch synthetische Kopien natürlich vorkommender Substanzen sein (zum Beispiel Melatonin). Alle Produkte mit diesen Inhaltsstoffen müssen in den Vereinigten Staaten als Nahrungsergänzungsmittel gekennzeichnet sein. ^[11] Wie bei Lebensmitteln, aber im Gegensatz zu Medikamenten, ist keine staatliche Genehmigung erforderlich, um Nahrungsergänzungsmittel herzustellen oder zu verkaufen; Stattdessen bestätigt der Hersteller selbst die Sicherheit von Nahrungsergänzungsmitteln. Anstatt eine Risiko-Nutzen-Analyse zu verlangen, um zu beweisen, dass das Produkt wie ein Medikament verkauft werden kann, wird diese Bewertung von der FDA nur verwendet, um zu entscheiden, dass ein Nahrungsergänzungsmittel unsicher ist und vom Markt genommen werden sollte. ^[11]

Ein Vitamin ist eine organische Verbindung, die ein Organismus als lebenswichtiger Nährstoff in begrenzten Mengen benötigt. ^[12] Eine organische chemische Verbindung (oder verwandte Verbindungen) wird als Vitamin bezeichnet, wenn sie von einem Organismus nicht in ausreichender Menge synthetisiert werden kann und aus der Ernährung gewonnen werden muss. Der Begriff ist sowohl von den Umständen als auch von dem jeweiligen Organismus abhängig. Zum Beispiel ist Ascorbinsäure (Vitamin C) ein Vitamin für anthropoide Primaten, Menschen, Meerschweinchen und Fledermäuse, aber nicht für andere Säugetiere. Vitamin D ist kein essentieller Nährstoff für Menschen, die ausreichend UV-Licht ausgesetzt sind – sei es von der Sonne oder einer künstlichen Quelle –, da sie Vitamin D in der Haut synthetisieren. ^[13] Menschen benötigen dreizehn Vitamine in ihrer Ernährung, von denen die meisten tatsächlich Gruppen verwandter Moleküle, sogenannte "Vitamere", sind (z. B. enthält Vitamin E Tocopherole und Tocotrienole, Vitamin K enthält Vitamin K₁ und K₂). Die Liste: die Vitamine A, C, D, E, K, Thiamin (B₁), Riboflavin (B₂), Niacin (B₃), Pantothensäure (B₅), Vitamin B₆, Biotin (B₇), Folsäure (B₉) und Vitamin B₁₂. Die Vitaminzufuhr unter den empfohlenen Mengen kann zu Anzeichen und Symptomen führen, die mit einem Vitaminmangel verbunden sind. Es gibt kaum Hinweise auf einen Nutzen, wenn Vitamine als Nahrungsergänzungsmittel von gesunden Menschen eingenommen werden, die eine ausreichende Ernährung haben. ^[14]

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),^[15] but products are available without prescription at 10,000 IU.

Minerals are the exogenous chemical elements indispensable for life. Four minerals – carbon, hydrogen, oxygen, and nitrogen – are essential for life but are so ubiquitous in food and drink that these are not considered nutrients and there are no recommended intakes for these as minerals. The need for nitrogen is addressed by requirements set for protein, which is composed of nitrogen-containing amino acids. Sulfur is essential, but for humans, not identified as having a recommended intake per se. Instead, recommended intakes are identified for the sulfur-containing amino acids methionine and cysteine. There are dietary supplements that provide sulfur, such as taurine and methylsulfonylmethane.

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.^[16]

• "Adequate calcium throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis."
• "Adequate calcium as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life."
• "Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis."
• "Adequate calcium and vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life."

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.^[17] The U.S. FDA also approved Qualified Health Claims (QHCs) for various health conditions for calcium, selenium and chromium picolinate.^[18] 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."^[19]

Individuals with hypokalemic sensory overstimulation are sometimes diagnosed as having attention deficit hyperactivity disorder (ADHD), raising the possibility that a subtype of ADHD has a cause that can be understood mechanistically and treated in a novel way. The sensory overload is treatable with oral potassium gluconate.

Protein-containing supplements, either ready-to-drink or as powders to be mixed into water, are marketed as aids to people recovering from illness or injury, those hoping to thwart the sarcopenia of old age,^[20][21] to athletes who believe that strenuous physical activity increases protein requirements,^[22] to people hoping to lose weight while minimizing muscle loss, i.e., conducting a protein-sparing modified fast,^[23] and to people who want to increase muscle size for performance and appearance. Whey protein is a popular ingredient,^[21][24][25] but products may also incorporate casein, soy, pea, hemp or rice protein. A meta-analysis found a moderate degree of evidence in favor of whey protein supplements use as a safe and effective adjunct to an athlete's training and recovery, including benefits for endurance, average power, muscle mass, and reduced perceived exercise intensity.^[26]

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.^[27][28][29] Scientific reviews can conclude that a high protein diet, when combined with exercise, will increase muscle mass and strength,^[30][31][32] or conclude the opposite.^[33] 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.^[22] One review proposed a maximum daily protein intake of approximately 25% of energy requirements, i.e., approximately 2.0 to 2.5 g/kg.^[28]

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".^[34] 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.^[35][10] Liquid medical food products – for example, Ensure – are available in regular and high protein versions.

Proteins are chains of amino acids. 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.^[27] 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.^[36] In elderly people, supplementation with just leucine resulted in a modest (0.99 kg) increase in lean body mass.^[37] 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.^[38] 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.^[39]

Beauty supplements, particularly those aimed at improving the health of skin, hair, and nails, are commonly marketed within the wellness and supplement markets. These products typically include ingredients, such as collagen, which is reputed to improve the appearance and condition of skin, hair, and nails.^{[medical citation needed]} Other typical ingredients include biotin, keratin, and omega-3 fatty acids, which are promoted for their alleged benefits to skin and hair health. Demand for these beauty supplements has risen markedly in the 21st century.^{[citation needed]} Despite the apparent rise in demand, scientific evidence supporting the efficacy of ingredients like biotin for the purpose of hair growth remains unproven.^[42]

Fish oil is a commonly used fatty acid supplement because it is a source of omega-3 fatty acids.^[43] Fatty acids are strings of carbon atoms, having a range of lengths. If links are all single (C−C), then the fatty acid is called saturated; with one double bond (C=C), it is called monounsaturated; if there are two or more double bonds (C=C=C), it is called polyunsaturated. Only two fatty acids, both polyunsaturated, are considered essential to be obtained from the diet, as the others are synthesized in the body. The "essential" fatty acids are alpha-linolenic acid (ALA), an omega-3 fatty acid, and linoleic acid (LA), an omega-6 fatty acid.^[43][44] ALA can be elongated in the body to create other omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Plant oils, particularly seed and nut oils, contain ALA.^[43] 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.^[45] In the United States and Canada are Adequate Intakes for ALA and LA over various stages of life, but there are no intake levels specified for EPA and/or DHA.^[46]

Supplementation with EPA and/or DHA does not appear to affect the risk of death, cancer or heart disease.^[47][48] Furthermore, studies of fish oil supplements have failed to support claims of preventing heart attacks or strokes.^[49] 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.^[50]

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.^[51]

Dietary supplements can be manufactured using intact sources or extracts from plants, animals, algae, fungi or lichens, including such examples as ginkgo biloba, curcumin, cranberry, St. John's wort, ginseng, resveratrol, glucosamine and collagen.^[52][53][54] Products bearing promotional claims of health benefits are sold without requiring a prescription in pharmacies, supermarkets, specialist shops, military commissaries, buyers clubs, direct selling organizations, and the internet.^[53] While most of these products have a long history of use in herbalism and various forms of traditional medicine, concerns exist about their actual efficacy, safety and consistency of quality.^[55][56][57] Canada has published a manufacturer and consumer guide describing quality, licensing, standards, identities, and common contaminants of natural products.^[58]

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,^[59] with cannabidiol and mushroom product sales as the highest.^[60] 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.^[61]

Claimed benefits of using probiotic supplements are not supported by sufficient clinical evidence.^[62][63][64] Meta-analysis studies have reported a modest reduction of antibiotic-associated diarrhea and acute diarrhea in children taking probiotics.^[65] There is limited evidence in support of adults using mono-strain and multi-strain containing probiotics for the alleviation of symptoms associated with irritable bowel syndrome.^[66] Probiotic supplements are generally regarded as safe.^[67]

A meta-analysis provided preliminary evidence that men treated with supplements containing selenium, zinc, omega-3 fatty acids, coenzyme Q₁₀ or carnitines reported improvements in total sperm count, concentration, motility, and morphology.^[68] A review concluded that omega-3 taken through supplements and diet might improve semen quality in infertile men.^[69] A 2021 review also supported selenium, zinc, omega-3 fatty acids, coenzyme Q₁₀ or carnitines, but warned that "excessive use of antioxidants may be detrimental to the spermatic function and many of the over-the-counter supplements are not scientifically proven to improve fertility."^[70]

There is low quality and insufficient evidence for the use of oral antioxidant supplements as a viable treatment for subfertile woman.^[71] A review provided evidence that taking dehydroepiandrosterone before starting an in vitro fertilization series may increase pregnancy rates and decrease miscarriage likelihood.^[72]

Prenatal vitamins are dietary supplements commonly given to pregnant women to supply nutrients that may reduce health complications for the mother and fetus. Although prenatal vitamins are not meant to substitute for dietary nutrition, prenatal supplementation may be beneficial for pregnant women at risk of nutrient deficiencies because of diet limitations or restrictions. The most common components in prenatal vitamins include vitamins B₆, folate, B₁₂, C, D, E, iron and calcium.^[73]

Sufficient intake of vitamin B₆ can lower the risk of early pregnancy loss and relieve symptoms of morning sickness.^[74][75] Folate is also an essential nutrient for pregnant women to prevent neural tube defects.^[74] In 2006, the World Health Organization endorsed the recommendation for women of child-bearing age to consume 400 micrograms of folate through the diet daily if planning a pregnancy.^[76] 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.^[77] There is little evidence to suggest that vitamin D supplementation improves prenatal outcomes in hypertensive disorders and gestational diabetes.^[78][79] 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.^[80][81]

Iron supplementation can lower the risk of iron deficiency anemia for pregnant women.^[82] In 2020, the World Health Organization updated recommendations for adequate calcium levels during pregnancy to prevent hypertensive disorders.^{[83][needs update][84]}

In 2020, the American market for dietary supplements was valued at $140.3 billion,^[3] with the economic impact in the United States for 2016 estimated at $122 billion, including employment wages and taxes.^[85] A 2020 analysis projected that the global market for vitamins and dietary supplement products would reach $196.6 billion by 2028, where the growth in market size is largely attributed to recent technological advancements in product manufacturing, increased demand for products advertised as healthy, increased product availability, and population aging.^[86]

Over the period 2008 to 2011, the Government Accountability Office (GAO) of the United States received 6,307 reports of health problems (identified as adverse events) from use of dietary supplements containing a combination of ingredients in manufactured vitamins, minerals or other supplement products,^[87] with 92% of tested herbal supplements containing lead and 80% containing other chemical contaminants.^[88] Using undercover staff, the GAO also found that supplement retailers intentionally engaged in "unequivocal deception" to sell products advertised with baseless health claims, particularly to elderly consumers.^[88] Consumer Reports also reported unsafe levels of arsenic, cadmium, lead and mercury in several protein powder products.^[89] The Canadian Broadcasting Corporation (CBC) reported that protein spiking, i.e., the addition of amino acids to manipulate protein content analysis, was common.^[90] Many of the companies involved challenged CBC's claim.^[91]

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.^[56] 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.^[92] According to the NY-AG, only about 20% of the herbal supplements tested contained the plants claimed.^[92] 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.^[92]

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.^[93] 86% of the adulterated supplements were marketed for weight loss and sexual performance, with many containing prescription erectile dysfunction medication. Muscle building supplements were contaminated with anabolic steroids that can lead to health complications affecting the kidney, the heart, and cause gynecomastia.^[94] Multiple bodybuilding products also contained antidepressants and antihistamines. Despite these findings, fewer than half of the adulterated supplements were recalled.^[93]

The European Commission has published harmonized rules on supplement products to assure consumers have minimal health risks from using dietary supplements and are not misled by advertising.^[95]

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 food products subject to compliance with current Good Manufacturing Practices (CGMP) and labeling with science-based ingredient descriptions and advertising.^[96][97] 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.^[98] 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.^{[99][100][101]}

The U.S. Federal Trade Commission, which litigates against deceptive advertising in marketed products,^[102] established a consumer center to assist reports of false health claims in product advertising for dietary supplements.^[103] In 2017, the FTC successfully sued nine manufacturers for deceptive advertising of dietary supplements.^[104]

In the United States, manufacturers of dietary supplements are required to demonstrate safety of their products before approval is granted for commerce.^[105] Despite this caution, numerous adverse effects have been reported,^[87] including muscle cramps, hair loss, joint pain, liver disease, and allergic reactions, with 29% of the adverse effects resulting in hospitalization, and 20% in serious injuries or illnesses.^[87] The potential for adverse effects also occurs when individuals consume more than the necessary daily amount of vitamins or minerals that are needed to maintain normal body processes and functions.^[106] The incidence of adverse effects reported to the FDA were due to "combination products" that contain multiple ingredients, whereas dietary supplements containing a single vitamin, mineral, lipid product, and herbal product were less likely to cause adverse effects related to excess supplementation.^[87]

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.^[57] The incidence of liver injury 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.^[107] The most common liver injuries from weight loss and bodybuilding supplements involve hepatocellular damage with resulting jaundice, and the most common supplement ingredients attributed to these injuries are green tea catechins, anabolic steroids, and the herbal extract, aegeline.^[107] Weight loss supplements have also had adverse psychiatric effects.^[108] Some dietary supplements may also have adverse interactions with prescription medications that may enhance side effects or decrease therapeutic effects of medications.^[109]

Work done by scientists in the early 20th century on identifying individual nutrients in food and developing ways to manufacture them raised hopes that optimal health could be achieved and diseases prevented by adding them to food and providing people with dietary supplements; while there were successes in preventing vitamin deficiencies, and preventing conditions like neural tube defects by supplementation and food fortification with folic acid, no targeted supplementation or fortification strategies to prevent major diseases like cancer or cardiovascular diseases have proved successful.^[110]

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.^[111][112] 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.^[113][114]

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.^{[115][116]: 10}

The regulation of food and dietary supplements by the U.S. Food and Drug Administration (FDA) is governed by various statutes enacted by the United States Congress. Pursuant to the Federal Food, Drug, and Cosmetic Act and accompanying legislation, the FDA has authority to oversee the quality of substances sold as food in the United States, and to monitor claims made in the labeling about both the composition and the health benefits of foods.

Substances which the FDA regulates as food are subdivided into various categories, including foods, food additives, 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^[100] if not in compliance with GMPs, stop production, and if there is a health risk, require that the company conduct a recall.^[117] 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.^[118]

The European Union's (EU) Food Supplements Directive of 2002 requires that supplements be demonstrated to be safe, both in dosages and in purity.^[119] Only those supplements that have been proven to be safe may be sold in the EU without prescription. As a category of food, food supplements cannot be labeled with drug claims but can bear health claims and nutrition claims.^[120]

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.^[121] In 2004, along with two British trade associations, the Alliance for Natural Health (ANH) had a legal challenge to the Food Supplements Directive^[122] referred to the European Court of Justice by the High Court in London.^[123]

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,^[124] 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.^[125] 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.^[126]

During the COVID-19 pandemic in the United States, the FDA and Federal Trade Commission (FTC) warned consumers about marketing scams of fraudulent supplement products, including homeopathic remedies, cannabidiol products, teas, essential oils, tinctures and colloidal silver, among others.^[127][128] By August 2020, the FDA and FTC had issued warning letters to dozens of companies advertising scam products, which were purported "to be drugs, medical devices or vaccines. Products that claim to cure, mitigate, treat, diagnose or prevent disease, but are not proven safe and effective for those purposes, defraud consumers of money and can place consumers at risk for serious harm"^{[127][129][130]}

Examples of ongoing government research organizations to better understand the potential health properties and safety of dietary supplements are the European Food Safety Authority,^[8] the Office of Dietary Supplements of the United States National Institutes of Health,^[6][131] the Natural and Non-prescription Health Products Directorate of Canada,^[132] and the Therapeutic Goods Administration of Australia.^[133] Together with public and private research groups, these agencies construct databases on supplement properties, perform research on quality, safety, and population trends of supplement use, and evaluate the potential clinical efficacy of supplements for maintaining health or lowering disease risk.^[131]

As continual research on the properties of supplements accumulates, databases or fact sheets for various supplements are updated regularly, including the Dietary Supplement Label Database,^[134] Dietary Supplement Ingredient Database,^[135] and Dietary Supplement Facts Sheets of the United States.^[136] In Canada where a license is issued when a supplement product has been proven by the manufacturer and government to be safe, effective and of sufficient quality for its recommended use, an eight-digit Natural Product Number is assigned and recorded in a Licensed Natural Health Products Database.^[137] The European Food Safety Authority maintains a compendium of botanical ingredients used in manufacturing of dietary supplements.^[138]

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.^[139] 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.^[140] 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.^[141]

Um sicherzustellen, dass Nahrungsergänzungsmittel ausreichend qualitativ, standardisiert und sicher für den öffentlichen Konsum sind, konzentrierten sich die Forschungsbestrebungen auf die Entwicklung von Referenzmaterialien für die Herstellung und Überwachung von Nahrungsergänzungsmitteln. ^[138][142] Hochdosierte Produkte haben Forschungsaufmerksamkeit erhalten,^[131][143] insbesondere in Notfällen wie Vitamin-A-Mangel bei Mangelernährung bei Kindern,^[144] und für Frauen, die Folsäurepräparate einnehmen, um das Brustkrebsrisiko zu senken. ^[145]

In den Vereinigten Staaten hat die National Health and Nutrition Examination Survey (NHANES) die Gewohnheiten der Verwendung von Nahrungsergänzungsmitteln im Zusammenhang mit der Gesamtaufnahme von Nährstoffen bei Erwachsenen und Kindern untersucht. ^[131] Im Zeitraum von 1999 bis 2012 nahm der Einsatz von Multivitaminen ab, und es gab große Unterschiede in der Einnahme einzelner Nahrungsergänzungsmittel zwischen Untergruppen nach Alter, Geschlecht, Rasse/Ethnie und Bildungsstatus. ^[146] Besonderes Augenmerk wurde auf die Verwendung von Folatpräparaten durch junge Frauen gelegt, um das Risiko fetaler Neuralrohrdefekte zu senken. ^[147][148]

Es wurden nur begrenzte Forschungen am Menschen durchgeführt, um das Potenzial einer Nahrungsergänzung zu beeinflussen, das Krankheitsrisiko zu beeinflussen. Beispiele:

• Vitamin D – akute Atemwegsinfektionen^[149]
• Eisen – mütterliche Eisenmangelanämie und Nebenwirkungen auf den Fötus^[150]
• Mehrere Nahrungsergänzungsmittel – kein Hinweis auf einen Nutzen für eine geringere Todesrisiko, Herz-Kreislauf-Erkrankungen oder Krebs^[151]
• Magnesiumsupplementierung – zur Verringerung der Gesamtmortalität und der Krebssterblichkeit,^[152] sowie zur Verbesserung der Glukosewerte bei Menschen mit Diabetes und Insulinsensitivitätsparametern bei Menschen mit hohem Diabetesrisiko. ^[153]
• Folsäure allein oder mit B-Vitaminen – Schlaganfall^[154][155]

Eine akademische Übersicht aus dem Jahr 2017 zeigte eine steigende Häufigkeit von Leberschäden durch die Verwendung von pflanzlichen und Nahrungsergänzungsmitteln, insbesondere solchen mit Steroiden, grünem Tee-Extrakt oder mehreren Inhaltsstoffen. ^[107]

Der potenzielle Nutzen der Verwendung essentieller Nährstoffpräparate zur Senkung des Krankheitsrisikos wurde durch Ergebnisse ohne Wirkung oder schwache Evidenz in zahlreichen klinischen Übersichtsarbeiten, etwa bei HIV,^[156] oder Tuberkulose, widerlegt. ^[157]

Eine Überprüfung der bei clinicaltrials.gov registrierten klinischen Studien, die sowohl Medikamente als auch Nahrungsergänzungsmittel umfassen würden, berichtete, dass fast die Hälfte der abgeschlossenen Studien ganz oder teilweise von der Industrie gesponsert wurde. ^[158] Dies impliziert nicht automatisch eine Verzerrung, aber es gibt Hinweise darauf, dass aufgrund selektiver Nichtmeldung Ergebnisse zur Unterstützung eines potenziellen Medikaments oder Nahrungsergänzungsmittels eher veröffentlicht werden als Ergebnisse, die keinen statistisch signifikanten Nutzen nachweisen. ^[158][159] Ein Review berichtete, dass weniger als die Hälfte der registrierten klinischen Studien in peer-reviewten Fachzeitschriften veröffentlicht wurde. ^[160]

Die Verbesserung der öffentlichen Informationen über die Verwendung von Nahrungsergänzungsmitteln erfordert Investitionen in berufliche Ausbildungsprogramme, weitere Studien zu Bevölkerungs- und Nährstoffbedarf, die Erweiterung der Datenbank, die Förderung der Zusammenarbeit zwischen Regierungen und Universitäten sowie die Übersetzung der Forschung zu Nahrungsergänzungsmitteln in nützliche Informationen für Verbraucher, Gesundheitsfachkräfte, Wissenschaftler und politische Entscheidungsträger. ^[161] Ein zukünftiger Nachweis der Wirksamkeit durch die Verwendung von Nahrungsergänzungsmitteln erfordert hochwertige klinische Forschung mit streng qualifizierten Produkten und die Einhaltung etablierter Richtlinien für die Berichterstattung von Studienergebnissen (z. B. CONSORT-Leitlinien). ^[131]