What Kind of Medical Study Would Have Grandma Believe that Her Daily Multivitamin is Dangerous?

FOR IMMEDIATE RELEASE
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


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Consumer Labs just emailed this key points summary:

Women-Vitamin Study - Key Points -- You may have heard this week about a new study which found a higher risk of death among women who used certain supplements. It's a complicated study, but we've summarized some key findings. Bear in mind that only white women ages 55 to 69 were enrolled in the study and they were followed for 22 years.

Those taking calcium supplements had a 3.8% reduced risk of death. The calcium benefit ended, however, when taking more than 900 mg per day from supplements. It's worth noting that experts suggest many older women who take calcium supplements may not need to -- see the Calcium Supplement Review for more.

The mineral most strongly associated with an increased risk of death was iron, which showed a risk increase of 3.9% -- and the risk increased as the dose increased, particularly over 50 mg per day. However, the study grouped dosages of under 50 mg together, making it hard to determine the risk of low dosages of iron, such as those in many multivitamins. However, there is very little reason why a postmenopausal woman should be taking iron -- see the Iron Supplement Review for more.

Although not as statistically meaningful, other supplements were associated with the following increases in the risk of death during the study: multivitamins (2.4%), vitamin B6 (4.1%), folic acid (5.9%), magnesium (3.6%), zinc (3.0%), and copper (18.0%). An abstract of the study is online.

The bottom line: Don't take a supplement you don't need. If you want to know how much of each vitamin and mineral you need from your total diet and how much is too much, see our chart at www.consumerlab.com/RDAs

The multivitamin study did surprise me a little, but didn't make me question my protocol since I'm using very specific supplements. However, another study showing the harmful effects of Selenium and Vitamin E in men does have me concerned:

http://well.blogs.nytimes.com/2011/10/11/more-evidence-against-vitamin-use/

Thoughts? Does anyone know if the supplements tested were food-based or synthetic? I would think this would make a difference, no?

Maybe you're right. I skimmed the study looking for poor statistics or poor reasoning (like you often see in statin studies) but I didn't see any glaring flaws. Then I checked if anything had been said about this study on curezone, and I found this article.

http://www.naturalnews.com/024650_selenium_cancer_vitamin_E.html

...two previous even larger studies showed that taking vitamin E resulted in a 32% lower rate of prostate cancer and taking selenium resulted in a 60% lower incidence of prostate cancer...

(no citation provided for this)

Instead of using the natural form of Vitamin E considered most beneficial for health, d-alpha-tocopherol acetate, they used dl-alpha-tocopherol acetate. The "d" designation in front of the "alpha" indicates that the products are derived from natural sources such as vegetable oils or wheat germ. A prefix of "dl", such as in dl-alpha- tocopherol, shows that the vitamin has been synthesized from a petroleum base.