Several studies published in the January 2014 issue of the Annals of Internal Medicine cast some light on the the usefulness of popular vitamin supplements for specific uses. The end results were not positive.
A summary article that is very blunt on the topic.
Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements
Eliseo Guallar, MD, DrPH; Saverio Stranges, MD, PhD; Cynthia Mulrow, MD, MSc, Senior Deputy Editor; Lawrence J. Appel, MD, MPH; and Edgar R. Miller III, MD, PhD
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.
Here are the the specific research articles:
Vitamin and Mineral Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An Updated Systematic Evidence Review for the U.S. Preventive Services Task Force. Stephen P. Fortmann, MD; Brittany U. Burda, MPH; Caitlyn A. Senger, MPH; Jennifer S. Lin, MD, MCR; and Evelyn P. Whitlock, MD, MPH
Conclusion: Limited evidence supports any benefit from vitamin and mineral supplementation for the prevention of cancer or CVD. Two trials found a small, borderline-significant benefit from multivitamin supplements on cancer in men only and no effect on CVD.
Long-Term Multivitamin Supplementation and Cognitive Function in Men: A Randomized Trial Francine Grodstein, ScD*; Jacqueline O’Brien, ScD*; Jae Hee Kang, ScD; Rimma Dushkes, PhD; Nancy R. Cook, ScD; Olivia Okereke, MD; JoAnn E. Manson, MD, DrPH; Robert J. Glynn, PhD; Julie E. Buring, ScD; J. Michael Gaziano, MD, MPH; and Howard D. Sesso, ScD, MPH
Conclusion: In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits.
Oral High-Dose Multivitamins and Minerals After Myocardial Infarction: A Randomized Trial Gervasio A. Lamas, MD; Robin Boineau, MD, MA; Christine Goertz, DC, PhD; Daniel B. Mark, MD, MPH; Yves Rosenberg, MD; Mario Stylianou, PhD; Theodore Rozema, MD; Richard L. Nahin, PhD, MPH; Lauren Lindblad, MS; Eldrin F. Lewis, MD; Jeanne Drisko, MD; Kerry L. Lee, PhD, for the TACT (Trial to Assess Chelation Therapy)
Conclusion: High-dose oral multivitamins and multiminerals did not statistically significantly reduce cardiovascular events in patients after MI who received standard medications. However, this conclusion is tempered by the nonadherence rate.
Vitamins are big business worldwide, consisting of a major portion of the $68 Billion(USD) market. In the US,
Vitamins represent under $8.5 billion of the overall US vitamins and supplements market, over half of which is sales of multivitamins. Individual vitamins are showing faster market growth than multivitamins, with the former reaching 13% growth while the latter is closer to 2%, reports Euromontior. Individual vitamins showed the greatest increase at 13%, with B vitamins representing growth of more than 14%. According to Business Insights, vitamins and minerals market (but excluding other dietary supplements such as herbal pills, probiotics, etc.) will see compound annual growth of 4.5%, nearing $30 billion in 2015.
Following the publication of the report in the Annals of Internal Medicine Andre Picard, wrote in the Globe and Mail:
There are times when supplements are appropriate, essential even:
- Every woman of child-bearing age should take a prenatal vitamin or, at the very least, folic acid. If a woman becomes pregnant, the micronutrient supplementation can prevent such grave conditions as spina bifida and such cancers as neuroblastoma in her child;
- Newborns should get vitamin K injections to avoid potentially life-threatening bleeding;
- Babies should take vitamin D drops, especially if they are breastfeeding (formula and cow’s milk are already fortified with vitamin D);
- Iron pills are an effective and necessary treatment for anemia;
- People in northern climes can lack vitamin D (especially if they are darker-skinned), and supplements can be helpful if they don’t routinely get adequate sunshine;
- Vitamin B12 deficiency is common in older people, and many should take supplements, especially if they take medications like Nexium or Zantac for gastrointestinal ailments.
What people don’t need is a cupboard overflowing with vitamin supplements or megadoses of particular nutrients.
In other words, there is a time when vitamin supplements are important to the health of some people. Picard`s criticism is the sweeping statement that one should avoid vitamins at all costs.
There are several things to remember when considering purchasing vitamin supplements:
- There are no positive effects from taking daily vitamins unless recommended by an MD for a specific disorder
- Large doses often be harmful
- They have no effect in the prevention of disease
- The primary negative effect of taking a daily multi-vitamin every day is that it is an unnecessary expense.
Also remember, for the purposes of Canadian law, vitamins are regulated under Natural Health Products Regulations and as such, are under much less scrutiny than most other consumer products. A perfect example of caveat emptor.