WASHINGTON — The Council for Responsible Nutrition on Tuesday issued sharp criticism in response to the study, "Dietary Supplements and Mortality Rate in Older Women," published in the Archives of Internal Medicine, a publication of the American Medical Association.
The study listed a broad range of supplements — multivitamins, folic acid, iron and copper, among others — that appear to be associated with an increased risk of death in older women. The article is part of the journal’s "Less Is More" series.
Jaakko Mursu, a doctor associated with the University of Eastern Finland and the University of Minnesota, used data collected during the "Iowa Women’s Health Study" to examine the association between vitamin and mineral supplements and mortality rate among 38,772 older women (average age 61.6 years). Supplement use was self-reported in 1986, 1997 and 2004 via questionnaires.
Among the 38,772 women who started follow-up with the first survey in 1986, 15,594 deaths (40.2%) occurred over an average follow-up time of 19 years. After adjustment, use of multivitamins, vitamin B6, folic acid, iron, magnesium, zinc and copper, were all associated with increased risk of death in the study population. Conversely, calcium supplements appear to reduce risk of mortality. The association between supplement intake and mortality risk was strongest with iron, and the authors found a dose-response relationship as increased risk of mortality was seen at progressively lower doses as women aged throughout the study.
“Based on existing evidence, we see little justification for the general and widespread use of dietary supplements,” the authors concluded. “We recommend that they be used with strong medically based cause, such as symptomatic nutrient deficiency disease.”
"[That] basically means these researchers would rather wait till we all get scurvy before acknowledging any need for supplemental nutrients," countered Duffy MacKay, CRN VP scientific and regulatory affairs.
"It's important to keep in mind that this is an associative — not a cause and effect — study," he said. "In fact, when the authors did their initial … analysis, it appears they actually found benefit for many of the supplements, not just calcium; yet instead of stopping there, they went on to 'further adjust' the data, possibly until they found statistics worthy of this publication's acceptance," MacKay surmised. "The study may make for interesting scientific water cooler discussion, but certainly does not warrant sweeping, overstated concerns for elderly women."
CRN's advice to consumers: "Your best chance for living a long and healthy life is to engage in healthy lifestyle practices, and many in the scientific community maintain that rational, reasonable use of vitamins and other supplements is part of that equation. Talk to your doctor, or other healthcare practitioner, if you have concerns — but read between the lines of individual studies and don't make your decisions, either for or against supplements, based solely on hype."