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A multivitamin is a preparation intended to serve as a
dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
with vitamins, dietary minerals, and other nutritional elements. Such preparations are available in the form of tablets, capsules, pastilles, powders, liquids, or injectable formulations. Other than injectable formulations, which are only available and administered under medical supervision, multivitamins are recognized by the Codex Alimentarius Commission (the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoni ...
' authority on food standards) as a category of
food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is in ...
. In healthy people, most scientific evidence indicates that multivitamin supplements do not prevent
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, heart disease, or other ailments, and regular supplementation is not necessary. However, specific groups of people may benefit from multivitamin supplements, for example, people with poor nutrition or those at high risk of
macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, so ...
. There is no standardized scientific definition for multivitamin. In the United States, a multivitamin/mineral supplement is defined as a supplement containing three or more vitamins and minerals that does not include
herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicina ...
s,
hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
s, or
drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhala ...
s, where each vitamin and mineral is included at a dose below the tolerable upper intake level as determined by the Food and Drug Board, and does not present a risk of adverse health effects.


Products and components

Many multivitamin ''formulas'' contain
vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) ...
, B1, B2, B3, B5, B6, B7, B9, B12, A, E, D2 (or D3), K,
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
,
iodine Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , ...
, selenium, borate,
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
,
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
,
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
,
manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...
, molybdenum, beta carotene, and/or
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
. Multivitamins are typically available in a variety of formulas based on age and sex, or (as in prenatal vitamins) based on more specific nutritional needs; a multivitamin for men might include less iron, while a multivitamin for seniors might include extra vitamin D. Some formulas make a point of including extra antioxidants. Some nutrients, such as calcium and magnesium, are rarely included at 100% of the recommended allowance because the pill would become too large. Most multivitamins come in capsule form; tablets, powders, liquids, and injectable formulations also exist. In the United States, the FDA requires any product marketed as a "multivitamin" to contain at least three vitamins and minerals; furthermore, the dosages must be below a "tolerable upper limit", and a multivitamin may not include herbs, hormones, or drugs.


Uses

For certain people, particularly for older people, supplementing the diet with additional vitamins and minerals can have health impacts; however, the majority will not benefit. People with dietary imbalances may include those on restrictive diets and those who cannot or will not eat a nutritious diet. Pregnant women and elderly adults have different nutritional needs than other adults, and a multivitamin may be indicated by a physician. Generally, medical advice is to avoid multivitamins during pregnancy, particularly those containing vitamin A, unless they are recommended by a health care professional. However, the NHS recommends 10μg of Vitamin D per day throughout the pregnancy and whilst breastfeeding, as well as 400μg of folic acid during the first trimester (first 12 weeks of pregnancy). Some women may need to take iron, vitamin C, or calcium supplements during pregnancy, but only on the advice of a doctor. In the 1999–2000
National Health and Nutrition Examination Survey The National Health and Nutrition Examination Survey (NHANES) is a survey research program conducted by the National Center for Health Statistics (NCHS) to assess the health and nutritional status of adults and children in the United States, a ...
, 52% of adults in the United States reported taking at least one dietary supplement in the last month and 35% reported regular use of multivitamin-multimineral supplements. Women versus men, older adults versus younger adults, non-Hispanic whites versus non-Hispanic blacks, and those with higher education levels versus lower education levels (among other categories) were more likely to take multivitamins. Individuals who use dietary supplements (including multivitamins) generally report higher dietary nutrient intakes and healthier diets. Additionally, adults with a history of prostate and breast cancers were more likely to use dietary and multivitamin supplements.


Precautions

The amounts of each vitamin type in multivitamin formulations are generally adapted to correlate with what is believed to result in optimal health effects in large population groups. However, these standard amounts may not correlate what is optimal in certain subpopulations, such as in children, pregnant women and people with certain medical conditions and medication. The health benefit of vitamins generally follows a biphasic dose-response curve, taking the shape of a bell curve, with the area in the middle being the safe-intake range and the edges representing deficiency and
toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
. For example, the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
recommends that adults on a 2,000 calorie diet get between 60 and 90 milligrams of vitamin C per day. This is the middle of the bell curve. The upper limit is 2,000 milligrams per day for adults, which is considered potentially dangerous. In particular, pregnant women should generally consult their doctors before taking any multivitamins: for example, either an excess or deficiency of vitamin A can cause birth defects. Long-term use of beta-carotene, vitamin A, and vitamin E supplements may shorten life, and increase the risk of lung cancer in people who smoke (especially those smoking more than 20 cigarettes per day), former smokers, people exposed to asbestos, and those who use alcohol. Many common brand supplements in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
contain levels above the DRI/RDA amounts for some vitamins or minerals. Severe vitamin and mineral deficiencies require medical treatment and can be very difficult to treat with common over-the-counter multivitamins. In such situations, special vitamin or mineral forms with much higher potencies are available, either as individual components or as specialized formulations. Multivitamins in large quantities may pose a risk of an acute overdose due to the toxicity of some components, principally
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
. However, in contrast to iron tablets, which can be lethal to children, toxicity from overdoses of multivitamins are very rare. There appears to be little risk to supplement users of experiencing acute side effects due to excessive intakes of micronutrients. There also are strict limits on the retinol content for vitamin A during pregnancies that are specifically addressed by prenatal formulas. As noted in dietary guidelines from Harvard School of Public Health in 2008, multivitamins should not replace healthy eating, or make up for unhealthy eating. In 2015, the
U.S. Preventive Services Task Force The United States Preventive Services Task Force (USPSTF) is "an independent panel of experts in primary care and prevention that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventive services". ...
analyzed studies that included data for about 450,000 people. The analysis found no clear evidence that multivitamins prevent cancer or heart disease, helped people live longer, or "made them healthier in any way."


Research

Provided that precautions are taken (such as adjusting the vitamin amounts to what is believed to be appropriate for children, pregnant women or people with certain medical conditions), multivitamin intake is generally safe, but research is still ongoing with regard to what health effects multivitamins have. Evidence of health effects of multivitamins comes largely from
prospective cohort studies A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome. F ...
which evaluate health differences between groups that take multivitamins and groups that do not. Correlations between multivitamin intake and health found by such studies may not result from multivitamins themselves, but may reflect underlying characteristics of multivitamin-takers. For example, it has been suggested that multivitamin-takers may, overall, have more underlying diseases (making multivitamins appear as less beneficial in prospective cohort studies). On the other hand, it has also been suggested that multivitamin users may, overall, be more health-conscious (making multivitamins appear as more beneficial in prospective cohort studies). Randomized controlled studies have been encouraged to address this uncertainty.


Cohort studies

In February 2009, a study conducted in 161,808 postmenopausal women from the Women's Health Initiative clinical trials concluded that after eight years of follow-up "multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease, or total mortality". Another 2010 study in the '' Journal of Clinical Oncology'' suggested that multivitamin use during
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemother ...
for stage III colon cancer had no effect on the outcomes of treatment. A very large prospective cohort study published in 2011, including more than 180,000 participants, found no significant association between multivitamin use and mortality from all causes. The study also found no impact of multivitamin use on the risk of cardiovascular disease or cancer. A cohort study that received widespread media attention is the Physicians' Health Study II (PHS-II). PHS-II was a double-blind study of 14,641 male U.S. physicians initially aged 50 years or older (mean age of 64.3) that ran from 1997 to June 1, 2011. The mean time that the men were followed was 11 years. The study compared total cancer (excluding non-melanoma skin cancer) for participants taking a daily multivitamin ( Centrum Silver by
Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation headquartered on 42nd Street in Manhattan, New York City. The company was established in 1849 in New York by two German entrepreneurs, Charles Pfize ...
) versus a
placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general ...
. Compared with the placebo, men taking a daily multivitamin had a small but
statistically significant In statistical hypothesis testing, a result has statistical significance when it is very unlikely to have occurred given the null hypothesis (simply by chance alone). More precisely, a study's defined significance level, denoted by \alpha, is the p ...
reduction in their total incidence of cancer. In absolute terms the difference was just 1.3 cancer diagnoses per 1000 years of life. The hazard ratio for cancer diagnosis was 0.92 with a 95%
confidence interval In frequentist statistics, a confidence interval (CI) is a range of estimates for an unknown parameter. A confidence interval is computed at a designated ''confidence level''; the 95% confidence level is most common, but other levels, such as 9 ...
spanning 0.86–0.998 (P = .04), this implies a benefit of between 14% and .2% over placebo in the confidence interval. No statistically significant effects were found for any specific cancers or for cancer mortality. As pointed out in an editorial in the same issue of the '' Journal of the American Medical Association'', the investigators observed no difference in the effect whether the study participants were or were not adherent to the multivitamin intervention, which diminishes the dose–response relationship. The same editorial argued that the study did not properly address the
multiple comparisons problem In statistics, the multiple comparisons, multiplicity or multiple testing problem occurs when one considers a set of statistical inferences simultaneously or infers a subset of parameters selected based on the observed values. The more inferences ...
, in that the authors neglected to fully analyze all 28 possible associations in the study—they argue if this had been done the statistical significance of the results would be lost. Using the same PHS-II study researchers concluded that taking a daily multivitamin did not have any effect in reducing
heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...
s and other major cardiovascular events, MI, stroke, and CVD mortality.


Systematic reviews and meta-analyses

One major
meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting m ...
published in 2011, including previous cohort and case-control studies, concluded that multivitamin use was not significantly associated with the risk of
breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or ...
. It noted that one Swedish cohort study has indicated such an effect, but with all studies taken together, the association was not statistically significant. A 2012 meta-analysis of ten randomized, placebo-controlled trials published in the ''Journal of Alzheimer's Disease'' found that a daily multivitamin may improve immediate recall memory, but did not affect any other measure of cognitive function. Another meta-analysis, published in 2013, found that multivitamin-multimineral treatment "has no effect on mortality risk", and a 2013
systematic review A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on t ...
found that multivitamin supplementation did not increase mortality and might slightly decrease it. A 2014 meta-analysis reported that there was "sufficient evidence to support the role of dietary multivitamin/mineral supplements for the decreasing the risk of age-related cataracts." A 2015 meta-analysis argued that the positive result regarding the effect of vitamins on cancer incidence found in Physicians' Health Study II (discussed above) should not be overlooked despite the neutral results found in other studies. Looking at 2012 data, a study published in 2018 presented meta-analyses on cardiovascular disease outcomes and all-cause mortality. It found that "conclusive evidence for the benefit of any supplement across all dietary backgrounds (including deficiency and sufficiency) was not demonstrated; therefore, any benefits seen must be balanced against possible risks." The study dismissed the benefits of routinely taking supplements of vitamins C and D, beta-carotene, calcium, and selenium. Results indicated taking niacin may actually be harmful. In July 2019, another meta-analysis of 24 interventions in 277 trials was conducted and published in ''
Annals of Internal Medicine ''Annals of Internal Medicine'' is an academic medical journal published by the American College of Physicians (ACP). It is one of the most widely cited and influential specialty medical journals in the world. ''Annals'' publishes content relevan ...
'', including a total of almost 1,000,000 participants. The study generally concluded that the vast majority of multivitamins had no significant effect on survival or heart attack risk. The study found a significant effect on heart health in a low-salt diet, and a small effect due to omega-3 and
folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing a ...
supplements. This analysis supports the results of two early 2018 studies that found no conclusive benefits from multivitamins for healthy adults.


Expert bodies

A 2006 report by the U.S. Agency for Healthcare Research and Quality concluded that "regular supplementation with a single nutrient or a mixture of nutrients for years has no significant benefits in the primary prevention of cancer, cardiovascular disease, cataract, age-related macular degeneration or cognitive decline." However, the report noted that multivitamins have beneficial effects for certain sub-populations, such as people with poor nutritional status, that vitamin D and calcium can help prevent fractures in older people, and that zinc and antioxidants can help prevent age-related
macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, so ...
in high-risk individuals. A 2017 Cochrane Systematic Review found that multivitamins including vitamin E or beta carotene will not delay the onset of macular degeneration or prevent the disease, however, some people with macular degeneration may benefit from multivitamin supplementation as there is evidence that it may delay the progression of the disease. Including lutein and zeaxanthin supplements in with a multivitamin does not improve progression of macular degeneration. The need for high-quality studies looking at the safety of taking multivitamins has been highlighted. According to the Harvard School of Public Health: "... many people don't eat the healthiest of diets. That's why a multivitamin can help fill in the gaps, and may have added health benefits." The U.S. Office of Dietary Supplements, a branch of the
National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the lat ...
, suggests that multivitamin supplements might be helpful for some people with specific health problems (for example,
macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, so ...
). However, the Office concluded that "most research shows that healthy people who take an MVM ultivitamindo not have a lower chance of diseases, such as cancer, heart disease, or diabetes. Based on current research, it's not possible to recommend for or against the use of MVMs to stay healthier longer."


Regulations


United States

The first person to formulate vitamins in the US was Dr. Forrest C. Shaklee. Shaklee introduced a product he dubbed "Shaklee's Vitalized Minerals" in 1915, which he sold until adopting the now ubiquitous term "vitamin" in 1929. Because of their categorization as a
dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
by the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
(FDA), most multivitamins sold in the U.S. are not required to undergo the testing procedures typical of pharmaceutical drugs. However, some multivitamins contain very high doses of one or several vitamins or minerals, or are specifically intended to treat, cure, or prevent disease, and therefore require a prescription or medicinal license in the U.S. Since such drugs contain no new substances, they do not require the same testing as would be required by a New Drug Application, but were allowed on the market as drugs due to the
Drug Efficacy Study Implementation Drug Efficacy Study Implementation (DESI) was a program begun by the Food and Drug Administration (FDA) in the 1960s after the requirement (in the Kefauver-Harris Drug Control Act) that all drugs be efficacious as well as safe, was made part of US ...
program.


Australia

Vitamins are classed as low-risk medications by the Therapeutic Goods Administration (TGA), and are therefore not assessed for efficacy, unlike most medicines sold in Australia. They require that the product is safe and that claims of efficacy can only be made in regards to minor ailments. No claims can be made about serious conditions. The TGA does not examine the contents of the product and whether it is what the label says it is, but they claim to carry out "targeted and random surveillance of products on the market." They encourage people to report any unsafe products to them. The TGA, however, has been criticized, by people such as
Allan Asher Allan James Asher is an Australian lawyer, consumer advocate and campaigner. Early life, education and personal life Asher was born in Sydney on 16 February 1951, one of eight children. He grew up in the western suburbs of Sydney at Eastern Cree ...
, a regulatory expert and former deputy chair of the Australian Competition & Consumer Commission, for allowing more than a thousand types of claim, 86% of which are not supported by scientific evidence, including "softens hardness", "replenishes gate of vitality" and "moistens dryness in the triple burner".


See also

*
Dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
* Essential nutrient * Food fortification * Megavitamin therapy * Prenatal vitamins


References

{{Reflist, 2


External links


Dietary Supplement Fact Sheet: Multivitamin/mineral Supplements
from the U.S.
National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the lat ...

Safe upper levels for vitamins and minerals
– Report of the UK Food Standards Agency Expert Group on Vitamins and Minerals Vitamins