Pro198Leu polymorphism in the GPX1 gene has no influence on selenium biomarkers after Brazil nut consumption in rheumatoid arthritis patients

Background: Chronic inflammation and increased oxidative stress in rheumatoid arthritis (RA) patients can affect selenium (Se) nutritional status and the consumption of food sources such as Brazil nuts, can improve this condition. However, the presence of genetic polymorphisms in selenoproteins could influence Se biomarkers and their bioavailability. This study aimed to evaluate the effect of Brazil nut consumption on Se biomarkers in RA patients and the influence of Pro198Leu polymorphism in the GPX1 gene. Methods: : This study was conducted with 45 RA patients who consumed one unit of Brazil nut per day (300 μg/Se) for eight weeks. Blood and 24-hour urine collection were analyzed before and after the intervention to assess Se biomarkers and to obtain DNA and RNA samples. Gene expression of GPX1 and Pro198Leu (rs1050450) genotyping was determined by real-time PCR using TaqMan Assays. Results: : RA patients were Se deficiency and Brazil nut intake was efficient to improve all nutritional biomarkers related to this mineral. According to the genotypes, after Brazil nut intervention period both CC and CT+TT had a significant (P<0.05) change in Se biomarkers, except the CT+TT carriers for GPx1 concentration (P=0.136). The analysis considering the intervention time and genotype factors did not show significant variation for all Se biomarkers. Conclusion: The consumption of Brazil nuts for eight weeks was efficient to improve Se biomarkers in RA patients independent of the genotypes of Pro198Leu SNP in the GPX1 gene.