Nutritional Medicine
Anti-Vitamin studies
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?
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