NLM Director's Comments Transcript
Efficacy of Dietary Supplements?: 11/07/2011

URL of this page: http://www.nlm.nih.gov/medlineplus/podcast/transcript110411.html

Greetings from the National Library of Medicine and MedlinePlus.gov
Regards to all our listeners!
I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.
Here is what's new this week in MedlinePlus.

The results suggest the absolute death risk increased 5.9 percent when study participants took folic acid. The absolute death risk increased about four percent when participants took vitamin B6. Increases of three to four percent occurred if participants took iron, magnesium, and zinc. A 2.4 percent increase in absolute risk of death occurred when participants took multivitamins. Absolute risk provides comparatively rigorous and conservative statistical estimates of health risks.

The study of about 39,000 women (starting at age 62 and followed for up to 19 years) found no significant differences in the death rates comparing those who did and did not take vitamin A. Among the participants, taking calcium and Vitamin D supplements were associated with a comparatively significant decline in the risk of death. All participants were enrolled in the Iowa Women's Health Study, a comprehensive assessment of post-menopausal health that began in 1986.

About 85 percent of the participants in the Iowa Women's Health Study reported taking one dietary supplement in 2004. All study participants self-reported dietary supplement use.

The study's five authors explain the findings are not applicable to younger women, or men. The authors note the study was observational, or it compared groups of older women who did/did not take food supplements without exerting control about their use. As a result, the findings are not as clinically rigorous as a double blind, controlled clinical trial. The authors report the Iowa Women's Health Study does not assess some health and lifestyle variables, which could confound the statistical associations between some dietary supplements and ensuing death risks.

The authors report that more research is needed among diverse populations as well as more rigorous controls in order to confirm the study's suggested bidirectional associations for supplement use and the risk of death.

While a commentary accompanying the study notes (and we quote): 'the study is large, well designed, and well conducted' (end of quote), the study's authors acknowledge the study's conclusions are based on statistical associations rather than cause and effect.

Although the study's authors suggest the study's findings are not definitive, the authors of the accompanying commentary in the Archives of Internal Medicine counter there are parallels between the current study's results and other recent, research findings. In summarizing the current study's findings, the commentary's authors conclude (and we quote): 'We cannot recommend the use of vitamin and mineral supplements as a preventive measure, at least not in a well-nourished population. Those supplements do not replace or add to the benefits of eating fruits and vegetables and may cause unwanted health consequences' (end of quote).

A few days after the current study was released new research in the Journal of the American Medical Association reported men who took vitamin E experienced a slightly higher risk of developing prostate cancer. Paradoxically, the working hypothesis at the start of the JAMA study of 35,000 men was vitamin E would reduce the risk to develop prostate cancer.

The Archives of Internal Medicine estimates dietary supplements produce more than $20 billion in annual revenues.

Meanwhile, MedlinePlus.gov's dietary supplements health topic page provides comprehensive information about the use of diet supplements. Besides overviews about supplements [provided by the National Center for Complementary and Alternative Medicine (NCCAM) and the U.S. Food and Drug Administration (the FDA)], a link to a Harvard Medical School website called 'Who needs supplements,' directly addresses one of the pertinent questions raised by the current research.

The NCCAM and FDA overviews can be found in the 'start here' section of MedlinePlus.gov's dietary supplements health topic page. The Harvard Medical School link can be found in the 'related issues' section.
A link to specific information about the side effects (or adverse events) of taking dietary supplements also is provided by the FDA and is available within the 'related issues' section.

MedlinePlus.gov's dietary supplements health topic page additionally contains research summaries, which are available in the 'research' section. Links to the latest pertinent journal research articles are available in the 'journal articles' section. Links to related clinical trials that may be occurring in your area are available in the 'clinical trials' section.

Answers to basic questions about the use and safety of specific supplements are available within the 'drugs and supplements' section near the top of MedlinePlus.gov's home page. There is additional information about a pill's effectiveness as well as possible interactions with other medications, foods, and dietary supplements.
Information about many popular vitamins is provided within the same section. Other background information can be found by typing 'NIH's Office of Dietary Supplements' in Google, Bing, or other search engines.

To find MedlinePlus.gov's dietary supplements health topic page, type 'dietary supplements' in the search box on MedlinePlus.gov's home page, then, click on 'dietary supplements (National Library of Medicine).'

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Please email Dr. Lindberg anytime at: NLMDirector@nlm.nih.gov
That's NLMDirector (one word) @nlm.nih.gov
A written transcript of recent podcasts is available by typing 'Director's comments' in the search box on MedlinePlus.gov's home page.
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A disclaimer –the information presented in this program should not replace the medical advice of your physician. You should not use this information to diagnose or treat any disease without first consulting with your physician or other health care provider.
It was nice to be with you. I look forward to meeting you here next week.
NLM Director's Comments Transcript - Efficacy of Dietary Supplements?: MedlinePlus
Older women who took folic acid, iron, copper, magnesium, zinc, vitamin B6, and multivitamins for almost two decades had a higher risk of death compared to non-users of dietary supplements, finds an intriguing study recently published in the Archives of Internal Medicine.