Multivitamin
[11] In the United States, a multivitamin/mineral supplement is defined as a supplement containing three or more vitamins and minerals that does not include herbs, hormones, or drugs, 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.
[12] Many multivitamin formulas contain vitamin C, B1, B2, B3, B5, B6, B7, B9, B12, A, E, D2 (or D3), K, potassium, iodine, selenium, borate, zinc, calcium, magnesium, manganese, molybdenum, beta carotene, and/or iron.
[16] 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.
Severe vitamin and mineral deficiencies require medical treatment and can be very difficult to treat with common over-the-counter multivitamins.
[23] There appears to be little risk to supplement users of experiencing acute side effects due to excessive intakes of micronutrients.
The analysis found no clear evidence that multivitamins prevent cancer or heart disease, helped people live longer, or "made them healthier in any way.
[29] Another 2010 study in the Journal of Clinical Oncology suggested that multivitamin use during chemotherapy for stage III colon cancer had no effect on the outcomes of treatment.
Compared with the placebo, men taking a daily multivitamin had a small but statistically significant reduction in their total incidence of cancer.
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.
[36] Using the same PHS-II study, researchers concluded that taking a daily multivitamin did not have any effect in reducing heart attacks and other major cardiovascular events, MI, stroke, and CVD mortality.
[37] One major meta-analysis published in 2011, including previous cohort and case-control studies, concluded that multivitamin use was not significantly associated with the risk of breast cancer.
[30] 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.
[40] 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.
[48] The history of multivitamins begins in the early 20th century when advancements in nutritional science led to the discovery of essential vitamins and minerals.
[49] These supplements were seen as a practical solution to combat malnutrition, improving public health by providing vital nutrients that were otherwise scarce.
However, as marketing strategies evolved, the emphasis shifted from necessity to preventative health and general well-being,[51] often without sound scientific backing.
[56] Ethnographic research has investigated possible reasons behind the widespread use of multivitamins in societies where scientific knowledge is dominant, despite the limited empirical evidence supporting new products.
[57][58] In 2019, a systematic review and meta-analysis examining the relationship between ‘maternal multivitamin supplementation’ and children being diagnosed with autism spectrum disorder (ASD) was published in Nutritional Research.
The research was conducted in the previous year and involved using the ‘random effects’ model on 9 independent trials consisting of 231,163 children across 4459 cases.
The results of this study indicated that pregnant women using multivitamin supplements during the prenatal period reduced the risk of their children being diagnosed with autism compared to their counterparts.
[59] In 2021, a similar systematic review and meta-analysis examining the relationship between prenatal multivitamins and children being diagnosed with autism spectrum disorder (ASD) was published in Nutrients.
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.
[63] 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.
The TGA, however, has been criticized, by people such as Allan Asher, 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".
