Abstract
Background: There is evidence that inadequate plasma selenium can adversely affect the maintenance of optimal health. Therefore, reported decrease in plasma selenium in an ageing population gives cause for concern. To further examine this hypothesis, we explored the relationships between plasma selenium and mortality in an elderly population; the EVA study (“Etude du vieillissement artériel”). Methods: The EVA study was a 9-year longitudinal study with 6 waves of follow-ups. During the two-year period 1991-1993 (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 different variables: socio-demographic characteristics, consumption habits, health and cognitive factors. Results: During the 9 year- follow-up, 101 subjects died. Baseline plasma selenium was higher in subjects that were alive at the end of follow-up (1.10±0.20μmol/L) compared to subjects that died during the follow-up (1.01±0.20μmol/L, p<10-4). Mortality was significantly higher in subjects with low level of selenium (units=0.2 µmol/L, RR=1.56 [1.28; 1.89]). After controlling for various potential confounding factors, this remained a significant association (RR=1.54 [1.25; 1.88]). When considering underlying causes of death, we found an association with mortality by cancer, (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 give additional arguments to enhance large interventional randomised trials with selenium in elderly populations to confirm the interest of this essential trace element in ageing.