Plain language summary
Previous studies have found that cystic fibrosis (CF) patients have lower blood selenium concentrations than healthy individuals. It is thought that this is likely to be an effect of the disease, rather than a cause. Selenium is needed for the production of glutathione peroxidase, an antioxidant enzyme that protects cells from oxidative damage. The purpose of this study was to investigate the selenium status of CF patients before and after supplementation with selenium. In this double-blind, cross-over trial, patients were given 2.8 micrograms of sodium selenite per kg of bodyweight per day for 5 months. At the start of the trial, selenium concentrations in the blood of CF patients were about the same as those seen in healthy people. After supplementation, both selenium and glutathione peroxidase levels increased. One explanation for the apparently normal levels of selenium seen in CF patients before the start of the study was that many of the patients had been self-supplementing with selenium before the study began. The authors recommend that the selenium status of every CF patient should be checked, and supplementation given where needed.
Abstract
Twenty-seven cystic fibrosis patients received selenium supplementation (2.8 micrograms of sodium selenite per kilogram of body weight per day) or a placebo. This 5-month trial was conducted as a double-blind, placebo-controlled study. After an interval of 2 months, treatments of the two groups were interchanged (crossed over) for another 5-month period. A group of healthy subjects, living in the same area, was investigated simultaneously. No selenium deficiency was found either in plasma or in erythrocytes before the supplementation. This result was inconsistent with a previous study performed in 1988 in our laboratory. This change in selenium status can be explained by progress in the nutritional nursing care of children and by the addition of selenium to the diet. During the study, selenium concentrations in plasma decreased when patients received placebo treatment and increased during selenium intake. In one of the two groups a similar variation was found for glutathione peroxidase activities in plasma and erythrocytes, whereas erythrocyte selenium was normal and did not change in any group. Nowadays, in the Grenoble area, the selenium status of cystic fibrosis patients is close to normal. Nevertheless, this study indicates a fragile equilibrium, given that selenium concentrations cn be lowered by placebo or mildly increased by supplementation.
Methodological quality
Jadad score
:
4
Allocation concealment
:
Yes
