Author Affiliations: University of Eastern Finland, Kuopio Campus, Kuopio.
We thank Mursu and colleagues for a well-needed analysis of supplement use in relation to mortality.1 The findings deserve some thought. When addressing surprising associations like this, we believe one needs to ask questions such as, What kind of people use dietary supplements? And, For what purpose are the supplements taken? These questions lead to hypotheses like the following: the supplement users have more health problems to start with—motivating for supplement use; they have more health problems in their close relatives—increasing their own risk to develop adverse health later on and motivating for supplement use; and, they have early deaths in their close relatives or they do not belong to a long-living family—again encouraging supplement use. If these hypotheses would hold, they could offer some explanation as to why supplement use does not seem to produce long-term health benefits. One even expects to see a clear decrease in the association between supplement use and mortality if adjustments to accommodate these possible confounding factors are made.
Tuomainen T, Virtanen JK, Voutilainen S. Dietary Supplements and Mortality. Arch Intern Med. 2012;172(5):447-448. doi:10.1001/archinternmed.2011.1858