We sure are seeing an awful lot of correlative findings today, aren't we? Scientists at the University of Minnesota recently revealed that the use of multivitamins and supplements — like folic acid, vitamin B6, magnesium, zinc, copper and iron — are linked to higher death rates among older women.
Does that mean your daily vitamin is slowly killing you? Not necessarily. But it does raise important questions about the widespread use of dietary supplements.
The study — conducted by a team of researchers at the University of Minnesota, and published in the latest issue of Archives of Internal Medicine — assessed the use of vitamin and mineral supplements of close to 39,000 women over 19 years. The women averaged 62 years of age at the beginning of the study.
Of the 15 supplements analyzed by the researchers, 14 of them were associated with a higher likelihood of dying during the course of the study, with at absolute risk increase (i.e. the average risk to supplement-takers relative to women who didn't take supplements) of 2.4%. The one supplement associated with a lower risk was calcium, a finding the researchers say actually conflicts with previous findings.
It's important to remember that this research doesn't prove that the vitamins are directly responsible for an increased likelihood of mortality — a fact that the study's first author, epidemiologist Jaakko Mursu, readily admits. Mursu notes, for example, that the results could either be an indication that supplements are harmful in high amounts, or that women who took supplements were simply more likely to be sick from other causes, and died from these other diseases.
"However, we do know that most compounds are toxic in high amounts, and long-term use might predispose [a person] to detrimental outcomes," Mursu explained.
The researchers claim that their findings, even if they don't explore whether the supplements contribute directly to the causes of death among the women, raise questions about whether people should be popping supplements for vitamins and minerals that they don't really need.
"Until recently, the available data regarding the adverse effects of dietary supplements has been limited and grossly underreported. We think the paradigm 'the more, the better' is wrong," said Drs. Goran Bjelakovic and Christian Gluud, of the Center for Clinical Intervention Research at Copenhagen University, in an accompanying commentary. They continue:
We believe that for all micronutrients, risks are associated with insufficient and too-large intake. Low levels of intake increase the risk of deficiency. High levels of intake increase the risk of toxic effects and disease.