Orthomolecular Medicine News Service, October 12, 2011
What Kind of Medical Study Would Have Grandma Believe that Her Daily Multivitamin is Dangerous?
by Robert G. Smith, PhD
(OMNS, Oct 12, 2011) A newly released study suggests that multivitamin and nutrient supplements can increase the mortality rate in older women [1]. However, there are several concerns about the study's methods and significance.
- The study was observational, in which participants filled out a survey about their eating habits and their use of supplements. It reports only a small increase in overall mortality (1%) from those taking multivitamins. This is a small effect, not much larger than would be expected by chance. Generalizing from such a small effect is not scientific.
- The study actually reported that taking supplements of B-complex, vitamins C, D, E, and calcium and magnesium were associated with a lower risk of mortality. But this was not emphasized in the abstract, leading the non-specialist to think that all supplements were associated with mortality. The report did not determine the amounts of vitamin and nutrient supplements taken, nor whether they were artificial or natural. Further, most of the association with mortality came from the use of iron and copper supplements, which are known to be potentially inflammatory and toxic when taken by older people, because they tend to accumulate in the body [2,3,4]. The risk from taking iron supplements should not be generalized to imply that all vitamin and nutrient supplements are harmful.
- The study lacks scientific plausibility for several reasons. It tabulated results from surveys of 38,000 older women, based on their recall of what they ate over an 18-year period. But they were only surveyed 3 times during that period, relying only on their memory of what foods and supplements they took. This factor alone causes the study to be unreliable.
- Some of these women smoked (~15%) or had previously (~35%), some drank alcohol (~45%), some had high blood pressure (~40%), and many of them developed heart disease and/or cancer. Some preexisting medical conditions were taken into account by adjusting the risk factors, but this caused the study to contradict what we already know about efficacy of supplements. For example, the study reports an increase in mortality from taking vitamin D, when adjusted for several health-relevant factors. However, vitamin D has recently been clearly shown to be helpful in preventing heart disease [5] and many types of cancer [6], which are major causes of death. Furthermore, supplement users were twice as likely to be on hormone replacement therapy, which is a more plausible explanation for increased mortality than taking supplements.
- The effect of doctor recommendations was not taken into account. By their own repeated admissions, medical doctors and hospital nutritionists are more likely to recommend a daily multivitamin, and only a multivitamin, for their sicker patients. The study did not take this into account. All it did was tabulate deaths and attempt to correct the numbers for some prior health conditions. The numbers reported do not reflect other factors such as developing disease, side effects of pharmaceutical prescriptions, or other possible causes for the mortality. The study only reports statistical correlations, and gives no plausible cause for a claimed increase in mortality from multivitamin supplements.
- The effect of education was not taken into account. When a doctor gives advice about illnesses, well-educated people will often respond by trying to be proactive. Some will take drugs prescribed by the doctor, and some will try to eat a better diet, including supplements of vitamins and nutrients. This is suggested by the study itself: the supplement users in the survey had more education than those who did not take supplements. It seems likely, therefore, the participants who got sick were more likely to have taken supplements. Because those who got sick are also more likely to die, it stands to reason that they would also be more likely to have taken supplements. This effect is purely statistical; it does not represent an increase in risk that taking supplements of vitamins and essential nutrients will cause disease or death. This type of statistical correlation is very common in observational health studies and those who are health-conscious should not be confounded by it.
- The known safety of vitamin and nutrient supplements when taken at appropriate doses was not taken into account. The participants most likely took a simple multivitamin tablet, which contains low doses. Much higher doses are also safe [4,7], implying that the low doses in common multivitamin tablets are very safe. Further, because each individual requires different amounts of vitamins and nutrients, some people must take much higher doses for best health [8].
Summary: In an observational study of older women in good health, it was said that those who died were more likely to have taken multivitamin and nutrient supplements than those who did not. The effect was small, and does not indicate any reason for disease or death. Instead, the study's methods suggest that people who have serious health conditions take vitamin and mineral supplements because they know that supplements can help. Indeed, the study showed a benefit from taking B-complex, C, D, and E vitamins, and calcium and magnesium. Therefore, if those wanting better health would take appropriate doses of supplements regularly, they would likely continue to achieve better health and longer life.
(Robert G. Smith is Research Associate Professor, University of Pennsylvania Department of Neuroscience. He is a member of the Institute for Neurological Sciences and the author of several dozen scientific papers and reviews.)
References:
[1] Mursu J, Robien K, Harnack LJ, Park K, Jacobs DR Jr (2011) Dietary supplements and mortality rate in older women. The Iowa Women's Health Study. Arch Intern Med. 171(18):1625-1633.
[2] Emery, T. F. Iron and your Health: Facts and Fallacies. Boca Raton, FL: CRC Press, 1991.
[3] Fairbanks, V. F. "Iron in Medicine and Nutrition." Chapter 10 in Modern Nutrition in Health and Disease, editors M. E. Shils, J. A. Olson, M. Shike, et al., 9th ed. Baltimore, MD: Williams & Wilkins, 1999.
[4] Hoffer, A., A. W. Saul. Orthomolecular Medicine for Everyone: Megavitamin Therapeutics for Families and Physicians. Laguna Beach, CA: Basic Health Publications, 2008.
[5] Parker J, Hashmi O, Dutton D, Mavrodaris A, Stranges S, Kandala NB, Clarke A, Franco OH. Levels of vitamin D and cardiometabolic disorders: systematic review and meta-analysis. Maturitas. 2010 Mar;65(3):225-36.
[6] Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007 Jun;85(6):1586-91.
[7] Padayatty SJ, Sun AY, Chen Q, Espey MG, Drisko J, Levine M. Vitamin C: intravenous use by complementary and alternative medicine practitioners and adverse effects. PLoS One. 2010 Jul 7;5(7):e11414.
[8] Williams RJ, Deason G. (1967) Individuality in vitamin C needs. Proc Natl Acad SciUSA.57:16381641.
Also of Interest: Orthomolecular Medicine News Service, April 29, 2010. Multivitamins Dangerous? Latest News from the World Headquarters Of Pharmaceutical Politicians, Educators and Reporters. http://orthomolecular.org/resources/omns/v06n15.shtml
JAMA Article Is No Reason Not to Take Your Multivitamins
WASHINGTON, D.C. – Statement from Natural Products Association (NPA) Vice President of Scientific and Regulatory Affairs Cara Welch, Ph.D., about recent concerns regarding the alleged risks of dietary supplements in the Archives of Internal Medicine:
"The Natural Products Association advocates that consumers use dietary supplements as part of a healthy lifestyle. Most vitamin and mineral supplements are taken to address or prevent deficiencies. While we would prefer that Americans get these nutrients from their diet, studies have consistently shown that they do not take in the essential compounds they need.I'm always pleased to see analysis on the long-term effects of supplementation. This study, however, is quite limited in scope; the data is observational and self-reported so contributing factors are not addressed. Subsequently, the authors cannot conclude any cause and effect and there is no reason why women should change what they're doing based on this report.There are plenty of studies published that demonstrate the benefit of supplementation and fortification. This specific study should not dissuade the general public from the benefits of addressing a vitamin or mineral deficiency with dietary supplements. As always, consumers should discuss their supplement usage with their health care professional."
And from the UK -
Multivitamin study is “classic example of scientific reductionism”
By Shane Starling, 12-Oct-2011
Related topics: Minerals, Vitamins & premixes, Research
A study published this week in the Archives of Internal Medicine that found multivitamins, and iron and copper supplements, may increase mortality rates in older women, has been slammed by industry groups.
“This study is a classic example of scientific reductionism being used to fulfil a particular need,”said Robert Verkerk PhD, the Alliance for Natural Health International (ANHI) executive and scientific director.
“In this case, it’s supplement bashing…Our view is that the self-reporting questionnaires, and lack of any supporting data on nutrient status of the study’s subjects, means that the majority of the trends emerging from the adjusted data on which the study’s conclusions were based are likely to be anomalous.”
Dr Verkerk pointed to the positive findings for calcium supplementation as, “findings from much more robust studies”.
Unanswered questions
The UK Health Food Manufacturers' Association (HFMA) scientific adviser, Dr Michèle Sadler questioned the causality highlighted by the researchers.
“This type of study only demonstrates an association and does not tell us whether taking supplements caused these particular effects,” said Dr Sadler.
“The study has many other limitations including the unknown, longer term health status of women taking the supplements, which is more likely to be linked to mortality than the supplements themselves.”
“It’s a case of which comes first, the chicken or the egg, and raises the question of how many women were taking the supplements because of ill health. How such a wide range of essential nutrients is supposed to have these effects is another unanswered question.”
Forms
Dr Verkerk said the research was flawed in design.
“Another very important point is that many factors were not controlled for, and these likely contributed to uncontrolled sources of variation and confounding that were simply ignored. Among these is the crucial issue of the forms of nutrients taken, none of which were recorded in questionnaires.”
“For example, there are several studies that suggest that long-term use of high doses of synthetic vitamin E, beta-carotene and folic acid may increase the risk of death, these generally having at least some plausible mechanisms. But, where the natural forms are consumed, especially where these nutrients are obtained from dietary sources, quite the reverse is found.”
He said the researchers had, “knowingly, or unknowingly, played into the hands of the pharmaceutical industry, the single biggest contributor to, and controller of, medical research.”
The University of Minnesota researchers led by Jaakko Mursu, PhD, found, “several commonly used dietary vitamin and mineral supplements, including multivitamins, vitamins B6, and folic acid, as well as minerals iron, magnesium, zinc, and copper, were associated with a higher risk of total mortality.”
See NutraIngredients-USA.com coverage of the research here.
Source: Archive of Internal Medicine
2011, Volume 171, Issue 18, Pages 1625-1633
“Dietary Supplements and Mortality Rate in Older Women: The Iowa Women's Health Study”
Authors: J. Mursu, K. Robien, L.J. Harnack, K. Park, D.R. Jacobs Jr
Editorial: Archive of Internal Medicine
2011, Volume 171, Issue 18, Pages 1633-1634
Vitamin and Mineral Supplement Use in Relation to All-Cause Mortality in the Iowa Women's Health Study:
Comment on "Dietary Supplements and Mortality Rate in Older Women"
Authors: G. Bjelakovic, C. Gluu
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