CHICAGO—According to the authors of a newly published study, “Based on existing evidence, we see little justification for the general and widespread use of dietary supplements. We recommend they be used with strong medically based cause, such as symptomatic nutrient deficiency disease" (Arch Intern Med. 2011;171(18):1625-33). The study reported consuming dietary supplements, including multivitamins, folic acid, iron and copper, among others, appears to be associated with an increased risk of death in older women.
The use of dietary supplements in the United States has increased considerably over the last decade, according to background information in the article. Jaakko Mursu, Ph.D., of the University of Eastern Finland, Kuopio, Finland, and the University of Minnesota, Minneapolis, and colleagues used data collected during the Iowa Women’s Health Study to examine the association between vitamin and mineral supplements and mortality (death) 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 percent) occurred over an average follow-up time of 19 years. Self-reported supplement use increased substantially between 1986 and 2004, with 62.7 percent of women reporting use of at least one supplement daily in 1986, 75.1 percent in 1997 and 85.1 percent in 2004.
The authors found use of most supplements was not associated with reduced total mortality in older women, and many supplements appeared associated with increased mortality risk. 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.
Findings for both iron and calcium supplements were replicated in separate, short-term analyses with follow-up occurring at four years, six years and 10 years.
In response to these study findings, Steve Mister, president and CEO, the Council for Responsible Nutrition (CRN), commented: “Consumers continue to look for the best way to live long and healthy lives, and as much as we would like for science to easily give us answers, the fact is science is not black and white. But even more concerning is the recent drive to combine political agendas with what should be pure science. The supplement industry regularly gets accused of this practice—in some cases rightly so—yet medical journals seem to be given a pass, as if somehow they held no bias whatsoever.
“Within the article itself are a number of opinions, including: ‘Also, cumulative effects of widespread use, together with food fortification, have raised concern regarding exceeding upper recommended levels …’ It’s quite popular these days to talk about over nutrification, but in fact research consistently shows most people are falling short in several key nutrients.
“The authors advise that dietary supplements only be used ‘with strong medically based cause, such as symptomatic nutrient deficiency …’ Given the high dosages of iron reportedly being used by the women in the study, it is highly likely the participants were taking the high dosage of iron reported in the study under a physician’s care for an iron deficiency, which may itself have resulted in a shortened lifespan. But the piece purports to warn against over-the-counter (OTC) use of vitamins.
“The publication invited a commentary from a scientist whose opinion on supplements and their potential role in good health is already well-known, and whose own work has been the subject of controversy in scientific circles: ‘…Therefore, we believe politicians and regulatory authorities should wake up to their responsibility to allow only safe products on the market.’ In the spirit of true scientific discourse, wouldn’t it have been more appropriate to invite a commentary from a researcher who might have looked at the data in its entirety, with sufficient lead time, and provided a different perspective?
“Critics of dietary supplements will continue to advocate vitamins and minerals should be regulated like drugs, but even they should realize that although drugs undergo rigorous RCT testing, many safety issues for drugs still do exist. Furthermore if nutrients were regulated like drugs, the cost and availability of supplements would make it difficult for average consumers to make these products part of their healthy lifestyle.
“It’s time scientific journals acknowledge they have some biases, just like industry."
Duffy MacKay, N.D., vice president, scientific and regulatory affairs, CRN, also commented, stating: “Dietary supplements are used by more than 150 million Americans in combination with other healthy lifestyle habits. This study, however, attempts to tease out one piece of the healthy equation for good health—dietary supplements. CRN maintains that nutrients may be robbed of their beneficial effects when viewed as if they were pharmaceutical agents, with scientists looking to isolate those effects, good or bad.
"It’s important to keep in mind that this is an associative—not a cause and effect—study. Further, the authors themselves have noted additional limitations. In fact, when the authors did their initial [minimum adjusted] 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. The study may make for interesting scientific water-cooler discussion, but certainly does not warrant sweeping, overstated concerns for elderly women.
"Further, the authors show their own bias with this statement: ‘We recommend that [dietary supplements] be used with strong medically based cause, such as symptomatic nutrient deficiency…’, which basically means these researchers would rather wait till we all get scurvy before acknowledging any need for supplemental nutrients.
"Our 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."
Cara Welch, Ph.D., vice president, scientific & regulatory affairs, Natural Products Association (NPA), concurred with CRN’s comments, adding: “The majority of vitamin and mineral supplements are taken to address or prevent deficiencies. While we would prefer Americans get these nutrients from their diet, studies have consistently shown they do not take in the compounds essential for their health and supplementation can help. I’m always pleased to see research done on the long-term effects of supplementation; but this study is limited in that it is observational and self-reported so contributing factors are not addressed. There are plenty of studies published that demonstrate the benefit of supplementation and fortification, this specific study should not dissuade the general population from the benefit of addressing a vitamin/mineral deficiency with dietary supplements. And as always, consumers should discuss their supplement intake with their health care professional.
