Flawed Multivitamin Study?

Some of our patients have expressed concern regarding a recent study that makes a (fairly weak) association between post-menopausal women who take multivitamins and increased death rate. The short article below from Thorne Research addresses several flaws in the study and talks about why we should be careful about drawing conclusions from this study.

Some highlights include the fact that people who have a serious health condition are more likely to start or increase multivitamin intake. For instance, the fact that someone started taking vitamins after learning they had a heart condition does not mean that the vitamins caused eventual heart attack. There also was no effort made in the study to learn what quality the vitamins were or what form they were in how they were manufactured ect. I have found that there is a big difference in quality from one vitamin company to another. I have found for instance that one form of calcium (calcium carbonate) may actually cause joint problems whereas something like calcium citrate will be beneficial.

On the other hand, iron and copper can be toxic, especially if taken over a long period. That’s why I have one multivitamin with iron and copper for younger women and another without for post menopausal women and men of all ages. When I do use an iron supplement, for people who show anemia on blood tests, I test for low dose, organically cheleated forms like found in spirulina first.

Lastly, the researchers themselves cautioned against making causative conclusions based on their study (eg concluding that multivitamins were causing more deaths).

I think the upshot is that statistical studies need to be taken with a grain of salt and need to be looked at from a number of angles. Also perhaps certain vitamins are not good for everyone, especially in high doses. This illustrated benefit of being able to muscle test for the best supplements for each individual and *unique* patient in my practice!

The whole article rebutting the study is below for those who want more information.

Dr Hogg

October 17, 2011
To Thorne Research’s valued medical practitioners and their patients:
A recent study, “Dietary Supplements and Mortality Rate in Older Women,” published in the Archives of Internal Medicine, 2011, Volume 171(18):1625-1633, has caused some concern among the public about the safety of dietary supplements. We have thoroughly reviewed this study and share the following analysis in order to help you better understand the study’s design and its findings, and to help allay any concerns you may have.

The Study’s Design
This study is an analysis of data gleaned from 38,772 postmenopausal Caucasian women enrolled in the then-ongoing Iowa Women’s Health Study. The data for the study is based on the responses obtained through a self-administered questionnaire initially distributed in 1986, with two follow-up questionnaires distributed over the next 18 years, in 1997 and 2004. The questionnaires inquired about lifestyle practices, food intake, dietary supplement use, weight, smoking status, hormone replacement therapy, and the presence of diabetes or heart disease.

Although study participants were asked about their intake of dietary supplements, the study did not report how much of any specific nutrient was consumed. Nor was information elicited from the women regarding the chemical form of the supplement (e.g., picolinate versus sulfate) or the quality of the supplements that were taken. Furthermore, although the women were asked whether they took a “multivitamin,” the study does not define this term; i.e., the mineral, vitamin, and botanical content of the study’s universal “multivitamin” cannot be determined.

Finally, no attempt was made to verify the accuracy of the answers provided in the questionnaires, nor were any of the participating women asked why they were taking supplements, and no attempt was made to determine the impact of taking-or not taking-supplements on any specific individual.
One possible flaw to consider. It is well known that when an individual is diagnosed with a serious disease, such as cardiovascular disease or cancer, beginning or increasing the use of dietary supplements occurs commonly. If the new or increased supplement use were reported on a questionnaire, and then subsequent mortality resulted because of the underlying disease, the situation
could very possibly exist such that the individual’s death, while properly attributed
to the disease, would also be “associated” with the use of a dietary supplement.
Such an erroneous scenario is a highly likely flaw in the study’s design.

The Study’s Findings
The results of the study’s analysis claim to show a slightly higher risk of all-cause
mortality associated with the use of multivitamins, iron, and copper. In weighing
the study’s findings, however, it must be emphasized that the Iowa Women’s
Health Study is a retrospective study of already collected data. It is not a
prospective, controlled intervention study, i.e., it is not a “clinical trial,” in which
participants would be given a specific dietary supplement or a placebo and then
followed closely over time to observe not only the specific outcomes but also the
factors possibly contributing to those outcomes.

As can only be surmised retrospectively, individual circumstances change over
time, and a significant number of the women participants likely either changed or
began new dietary supplement regimens over the course of the 18 years they
were studied. And since there was no direct contact with the participants outside
of the mailed questionnaires, general information surrounding individual deaths
had to be obtained from public records; it was not ascertained by direct medical

With regard to iron and copper, it has been known for decades that both metals
can be potentially toxic, as exemplified by the multi-system disease states that
can result from hemochromatosis and Wilson’s disease, respectively. For this
reason, many postmenopausal women, like men, probably should not take an
iron supplement in the absence of anemia or a documented deficiency. At the
very least, iron and copper supplements should be taken concurrently with
antioxidants and/or antioxidant-rich foods to prevent a potential increase in
oxidative stress. Each of these circumstances points to the merits of dietary
supplements being recommended and overseen by medical professionals.

With regard to multivitamins, there is simply insufficient data that can be gleaned
from the study to make any serious conclusion about the impact of multivitamins
on mortality. This is due to the fact that there are literally thousands of different
combinations of vitamins, minerals, and botanicals that can be considered a
“multivitamin,” as well as a whole host of considerations such as quality, potency,
dosage, protocol, and indications for use, among others.

Practitioner and Patient Concerns
We believe there are serious flaws in the methodology, analysis, and findings on
which this study is based. Retrospective surveys such as this-in which people
are asked to recall years of dietary habits or supplement use-are notoriously
inaccurate. The only conclusion that can realistically be drawn is that a slight
statistical association was found based on a limited data set of questionable reliability-and a simple association does not reflect causation. The study’s authors do not disagree, stating the following in their commentary to the study: “It is not advisable to make a causal statement of excess risk based on these observational data…” We heartily agree with this advice.

When made by a quality manufacturer, when recommended by a knowledgeable health-care practitioner, and when taken for the appropriate indication, dietary supplements promote, enhance, support, and help maintain overall good health and well-being. The “results” of the recent study do not diminish this conclusion.

Alan Miller, ND Robert Rountree, MD
Director of Medical Education & Research Chief Medical Officer
Thorne Research, Inc.
For further commentary on this study:
The Alliance for Natural Health
The Council for Responsible Nutrition

Posted in Health Articles.