'Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements', the editorial in (2013) 159(12) Annals of Internal Medicine 850-851 comments
[S]upplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough.The journal notes that
Three articles in this issue address the role of vitamin and mineral supplements for preventing the occurrence or progression of chronic diseases. First, Fortmann and colleagues systematically reviewed trial evidence to update the U.S. Preventive Services Task Force recommendation on the efficacy of vitamin supplements for primary prevention in community-dwelling adults with no nutritional deficiencies. After reviewing 3 trials of multivitamin supplements and 24 trials of single or paired vitamins that randomly assigned more than 400 000 participants, the authors concluded that there was no clear evidence of a beneficial effect of supplements on all-cause mortality, cardiovascular disease, or cancer.
Second, Grodstein and coworkers evaluated the efficacy of a daily multivitamin to prevent cognitive decline among 5947 men aged 65 years or older participating in the Physicians’ Health Study II. After 12 years of follow-up, there were no differences between the multivitamin and placebo groups in overall cognitive performance or verbal memory. Adherence to the intervention was high, and the large sample size resulted in precise estimates showing that use of a multivitamin supplement in a well-nourished elderly population did not prevent cognitive decline. Grodstein and coworkers’ findings are compatible with a recent review of 12 fair- to good-quality trials that evaluated dietary supplements, including multivitamins, B vitamins, vitamins E and C, and omega-3 fatty acids, in persons with mild cognitive impairment or mild to moderate dementia. None of the supplements improved cognitive function.
Third, Lamas and associates assessed the potential benefits of a high-dose, 28-component multivitamin supplement in 1708 men and women with a previous myocardial infarction participating in TACT (Trial to Assess Chelation Therapy). After a median follow-up of 4.6 years, there was no significant difference in recurrent cardiovascular events with multivitamins compared with placebo (hazard ratio, 0.89 [95% CI, 0.75 to 1.07]). The trial was limited by high rates of nonadherence and dropouts.
Other reviews and guidelines that have appraised the role of vitamin and mineral supplements in primary or secondary prevention of chronic disease have consistently found null results or possible harms. Evidence involving tens of thousands of people randomly assigned in many clinical trials shows that β-carotene, vitamin E, and possibly high doses of vitamin A supplements increase mortality and that other antioxidants, folic acid and B vitamins, and multivitamin supplements have no clear benefit.The editorial precedes news last week that cash-strapped La Trobe University has entered into a controversial relationship with a vendor of 'supplements', despite that institution gaining international attention in preceding years for cogent critiques of some practice by what is now its new partner and recognition of exemplary work by consumer advocate Dr Ken Harvey. (Independent concerns are highlighted here and here.)
The Annals of Internal Medicine states that
Despite sobering evidence of no benefit or possible harm, use of multivitamin supplements increased among U.S. adults from 30% between 1988 to 1994 to 39% between 2003 to 2006, while overall use of dietary supplements increased from 42% to 53%. Longitudinal and secular trends show a steady increase in multivitamin supplement use and a decline in use of some individual supplements, such as β-carotene and vitamin E. The decline in use of β-carotene and vitamin E supplements followed reports of adverse outcomes in lung cancer and all-cause mortality, respectively. In contrast, sales of multivitamins and other supplements have not been affected by major studies with null results, and the U.S. supplement industry continues to grow, reaching $28 billion in annual sales in 2010. Similar trends have been observed in the United Kingdom and in other European countries.
The large body of accumulated evidence has important public health and clinical implications. Evidence is sufficient to advise against routine supplementation, and we should translate null and negative findings into action. The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries.
The evidence also has implications for research. Antioxidants, folic acid, and B vitamins are harmful or ineffective for chronic disease prevention, and further large prevention trials are no longer justified. Vitamin D supplementation, however, is an open area of investigation, particularly in deficient persons. Clinical trials have been equivocal and sometimes contradictory. For example, supplemental vitamin D, which might prevent falls in older persons, reduced the risk for falls in a few trials, had no effect in most trials, and increased falls in 1 trial. Although future studies are needed to clarify the appropriate use of vitamin D supplementation, current widespread use is not based on solid evidence that benefits outweigh harms.
With respect to multivitamins, the studies published in this issue and previous trials indicate no substantial health benefit. This evidence, combined with biological considerations, suggests that any effect, either beneficial or harmful, is probably small. As we learned from voluminous trial data on vitamin E, however, clinical trials are not well-suited to identify very small effects, and future trials of multivitamins for chronic disease prevention in well-nourished populations are likely to be futile.
In conclusion, β-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases. Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed— supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough.A comment by Jessica Fargnoli, Joyce Greenleaf and Melissa Hafner stated that
We share the authors’ concerns and have released two related reports that further highlight risks of dietary supplements based on our review of their labels. Manufacturers make claims on these labels that the Food and Drug Administration (FDA) has limited authority to review; however, consumers rely on those claims in purchasing supplements.
In the first report, we found that claims made on dietary supplement labels may be misleading. Specifically, we reviewed the substantiation for structure/function claims found in a sample of supplements marketed for weight loss and immune support. FDA requires that supplement manufacturers have substantiation to support such claims on their products’ labels. FDA has also issued guidance on the scientific support necessary to substantiate these claims. The substantiation for structure/function claims was not consistent with FDA recommendations that evidence be derived from high-quality human studies. Most studies we reviewed did not involve the actual supplement or test the supplement or its active ingredients in humans. Furthermore, 20% of the supplements’ labels bore claims that are prohibited by FDA, such as disease claims.
In the second report, we found that FDA may have difficulty locating dietary supplement companies in emergencies related to their products. We contacted the companies responsible for the supplements in our sample and found that 28% had facilities that failed to register with FDA as required. Of those that did register, 72% had incomplete or inaccurate contact information. And 20% of sample labels lacked the required contact information for adverse event reporting.
Based on our research, we share the authors’ view that consumers should be wary of dietary supplements’ claims of effectiveness and call on FDA to seek explicit authority to review those claims. Furthermore, FDA should improve the accuracy of its registry to ensure it can respond to a public health emergency related to dietary supplements.
