Selenium Up, Mortality Down

A study was recently published in the journal Clinical Chemistry defining the association between plasma selenium levels and increased risk of mortality in an elderly population involving almost 1400 subjects between the ages of 73 and 83.

After controlling for other factors, a significant association was found between those individuals with low plasma selenium levels and increased mortality rates by an amazing 54 percent. In addition, when the underlying causes of death were considered, we found an association with cancer-related mortality. The results of this study were totally consistent with findings from other large interventional studies including randomized trials suggesting that selenium may play a role in helping to maintain health.

Background: Inadequate plasma selenium can adversely affect the maintenance of optimal health; therefore, reported decreases in plasma selenium in an aging population are cause for concern. To further examine this hypothesis, we explored the relationships between plasma selenium and mortality in an elderly population: the EVA (Etude du Vieillissement Artériel) study.

Methods: The EVA study was a 9-year longitudinal study with 6 periods of follow-up. During the 2-year period from 1991 to 1993 (EVA0), 1389 men and women born between 1922 and 1932 were recruited. The effects of plasma selenium at baseline on mortality were determined by Cox proportional hazards regression analysis, adjusting for the following variables: sociodemographic characteristics, dietary habits, health, and cognitive factors.

Results: During the 9-year follow-up, 101 study participants died. Baseline plasma selenium was higher in individuals who were alive at the end of follow-up [mean (SD), 1.10 (0.20) µmol/L] than in those who died during the follow-up [1.01 (0.20) µmol/L; P <10–4]. Mortality rates were significantly higher in individuals with low selenium [increments = 0.2 µmol/L; relative risk (RR) = 1.56 (95% confidence interval, 1.28–1.89)]. After we controlled for various potential confounding factors, this association remained significant [RR = 1.54 (1.25–1.88)]. When the underlying causes of death were considered, we found an association with cancer-related mortality [adjusted RR = 1.79 (1.32–2.44)].

Conclusions: Even if it is premature to present selenium as a longevity indicator in an elderly population, our results are in accordance with those of large, interventional, randomized trials with selenium, which suggest that this essential trace element plays a role in health maintenance in aging individuals.

Source

N. Tasnime Akbaraly, Josiane Arnaud, Isabelle Hininger-Favier, Veronique Gourlet, Anne-Marie Roussel and Claudine Berr. Selenium and Mortality in the Elderly: Results from the EVA Study. Clinical Chemistry 51: 2117-2123, 2005. First published August 25, 2005

Key concepts: selenium, mortality