From Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Warwick Medical School, University of Warwick, Coventry, England, United Kingdom; Annals of Internal Medicine, American College of Physicians, Philadelphia, Pennsylvania; and Johns Hopkins School of Medicine, Baltimore, Maryland.Three articles in this issue address the role of vitamin and mineral supplements for preventing the occurrence or progression of chronic diseases.
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.
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 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.
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.
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. supplement industry continues to grow, reaching billion in annual sales in 2010.