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Background: The beneficial effects of selenium (Se) to human health are exerted by selenoproteins, which can be quantified in blood and used as biomarkers of Se status. Different responses of Se biomarkers after supplementation with selenomethionine and sodium selenite have been observed and some of them could be due to genetic polymorphisms, mainly single nucleotide polymorphisms (SNPs). Brazil nuts are known to be the richest natural source of Se., Objective: Investigate how genetic variations in selenoprotein genes modulate biomarkers of Se status in response to Brazil nut supplementation., Methods: The SU.BRA.NUT study was a four month interventional trial which involved healthy volunteers of both genders, selected in University of Sao Paulo. The supplementation was done with one Brazil nut a day for 8 weeks, followed by 8 weeks of washout. Blood samples were collected at 5 time points: baseline, 4 and 8 weeks of supplementation and 4 and 8 weeks of washout for analysis of five biomarkers of Se status - erythrocyte GPx1 (Glutathione Peroxidase 1) activity, plasma GPx3 activity, plasma Se, erythrocyte Se, and plasma selenoprotein P. The gene expression of GPX1, SELENOP, SELENOF and SELENOS was done before and after 8 weeks of supplementation. The volunteers were genotyped for SNPs in GPX1 (rs1050450, rs3811699 and rs1800699), GPX4 (rs713041), SELENOP (rs3877899 and rs7579), SELENOF (rs5845) and SELENOS (rs34713741)., Results: A total of 130 volunteers finished the protocol. The concentrations of four biomarkers of Se status increased significantly after 4 and 8 weeks of supplementation, being modulated by gender. In addition, erythrocyte GPx1 activity was associated with rs1050450, rs713041 and rs5845. Plasma Se was associated with rs7579 and selenoprotein P with plasma Se at baseline. Nut supplementation significantly increased GPX1 mRNA expression only in subjects with CC genotype at rs1050450. SELENOP mRNA expression was significantly lower in subjects with GG genotype at rs7579 before and after supplementation., Conclusion: Genetic variations in GPX1 and SELENOP genes are associated with different responses of molecular and biochemical biomarkers of Se status after Brazil nut supplementation in healthy Brazilians. The SU.BRA.NUT study was registred at www.clinicaltrials.gov as NCT 03111355., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

Purpose: The consumption of Brazil nuts has been associated with benefits to lipid metabolism and reductions in total cholesterol and LDL concentrations. They are the richest natural source of selenium which has essential functions in human physiology. Genetic polymorphisms in Selenoprotein P could impair lipid and glucose metabolisms. The aim of this work was to verify the influence of polymorphisms in genes for selenoproteins on blood lipid levels after dietary supplementation with Brazil nuts in healthy adults., Methods: The study included 130 healthy volunteers selected at the University of São Paulo, Brazil. They were supplemented with one nut a day for 8 weeks, followed by 8 weeks without intervention. The following analyses were performed: anthropometric measurements, serum fasting glucose, lipid profile, C-reactive protein and plasma MDA levels. The volunteers were genotyped for SNPs rs1050450, rs3811699, rs1800699, rs713041, rs3877899, rs7579, rs34713741, and rs5845 in genes for selenoproteins., Results: The concentrations of total cholesterol and fasting glucose levels decreased after 8 weeks of supplementation (p < 0.05). Glucose levels were modulated by rs3877899 in SEPP1, with significantly lower levels observed for individuals with the GA + AA genotype (p = 0.025). In addition, rs7579 was associated with cholesterol concentrations, which were significantly lower for individuals with the GG genotype (p = 0.053)., Conclusions: Supplementation with one Brazil nut a day for 8 weeks reduced total cholesterol and glucose levels. Furthermore, our results suggest that rs3877899 might be associated with glucose concentrations and rs7579 with cholesterol concentrations. Therefore, the effect of genetic variations should be considered in future nutritional interventions evaluating the response to Brazil nut supplementation.

Selenium (Se) is an essential micronutrient for human health. Its beneficial effects are exerted by selenoproteins, which can be quantified in blood and used as molecular biomarkers of Se status. We hypothesize that the presence of genetic polymorphisms in selenoprotein genes may: (1) influence the gene expression of specific selenoproteins and (2) influence the pattern of global gene expression after Brazil nut supplementation. The study was conducted with 130 healthy volunteers in Sao Paulo, Brazil, who consumed one Brazil nut (300 μg/Se) a day for eight weeks. Gene expression of GPX1 and SELENOP and genotyping were measured by real-time PCR using TaqMan Assays. Global gene expression was assessed by microarray using Illumina HumanHT-12 v4 BeadChips . Brazil nut supplementation significantly increased GPX1 mRNA expression only in subjects with CC genotype at rs1050450 ( p < 0.05). SELENOP mRNA expression was significantly higher in A-carriers at rs7579 either before or after supplementation ( p < 0.05). Genotype for rs713041 in GPX4 affected the pattern of blood cell global gene expression. Genetic variations in selenoprotein genes modulated both GPX1 and SELENOP selenoprotein gene expression and global gene expression in response to Brazil nut supplementation.