Selenium (Se) is a mineral with several biological functions, and studies have shown that its deficiency can be linked to many complications in patients with chronic kidney disease (CKD). This study aims to systematically review the effects of Se supplementation in patients with CKD undergoing haemodialysis (HD). This systematic review was carried out according to the PRISMA statement. Clinical trials were searched in PubMed, Lilacs, Embase, Scopus and Cochrane Library databases from inception to July 2021 and updated in July 2024. The protocol was registered on PROSPERO (CRD42021231444). Two independent reviewers performed the study screening and data extraction, and the risk of bias was evaluated using the Cochrane Collaboration tool. Thirteen studies were included in this review. Only nine studies showed results on Se levels; in all, reduced Se levels were observed before supplementation. A positive effect of supplementation on plasma Se level was demonstrated. Of the ten studies analysed, six demonstrated positive effects on antioxidant and inflammatory markers. Only one study analysed immunological parameters, showing a positive impact. From two studies that analysed thyroid hormones, only one showed positive results. All studies were classified as high risk of bias. The findings suggest that Se supplementation significantly increases plasma Se levels in these patients; however, there are still not enough studies to clarify the effects of Se supplementation on the antioxidant and inflammatory markers, immune system and thyroid hormones. Further studies are needed to elucidate the effects of Se supplementation and to provide a recommendation for patients with CKD undergoing HD.

As, Pb and Hg are common environmental contaminants in low- and middle-income countries. We investigated the association between child toxicant exposure and growth and development and determined if this association was mitigated by Se concentration. Toxicant concentrations in fingernail samples, anthropometry and Bayley’s Scales of Infant Development, 3rd edition domains were assessed in 36-month-old children whose mothers had been part of a randomised controlled trial in rural Vietnam. Multivariable regression analyses were performed to estimate the effect of toxicant exposure on clinical outcomes with adjustments for potential confounders and interaction with fingernail Se concentration. We analysed 658 children who had data for at least one physical or developmental outcome, and at least one toxicant measurement, and each of the covariates. Fingernail As concentration was negatively associated with language (estimate per 10 % increase in As: −0·19, 95 % CI: (–0·32, −0·05)). Pb was negatively associated with cognition (estimate per 10 % increase in Pb: −0·08 (–0·15, −0·02)), language (estimate per 10 % increase in Pb: −0·18 (–0·28, −0·10)) and motor skills (estimate per 10 % increase in Pb: −0·12 (–0·24, 0·00)). Hg was negatively associated with cognition (estimate per 10 % increase in Hg: −0·48, (–0·72, −0·23)) and language (estimate per 10 % increase in Hg −0·51, (–0·88, −0·13)) when Se concentration was set at zero in the model. As Se concentration increased, the negative associations between Hg and both cognition and language scores were attenuated. There was no association between toxicant concentration and growth. As, Pb and Hg concentrations in fingernails of 3-year-old children were associated with lower child development scores. The negative association between Hg and neurological development was reduced in magnitude with increasing Se concentration. Se status should be considered when assessing heavy metal toxicants in children and their impact on neurodevelopmental outcomes.

Determining the predictors of serum retinol at mid-pregnancy is relevant for planning interventions aimed at improving vitamin A status of pregnant women and their offspring. This prospective study assessed predictors of serum retinol at the beginning of the third trimester of pregnancy. We enrolled 442 pregnant women living in the urban area of Cruzeiro do Sul, Western Brazilian Amazon. Demographic, socio-economic, environmental and clinical characteristics as well as obstetric history, anthropometric, dietary and biochemical data, including serum retinol, were gathered between 16 and 20 gestational weeks. Serum retinol also measured at the beginning of the third trimester of pregnancy (approximately 28 gestational weeks) was the outcome of interest. Multiple linear regression models were used to evaluate associations with the outcome. Overall, the following variables explained serum retinol at the beginning of the third trimester of pregnancy in the adjusted model (R2 = 11·1 %): seasonality (winter season – November to April; β=0·134; 95 % CI 0·063, 0·206), weekly consumption of Amazonian fruits (β=0·087; 95 % CI 0·012, 0·162) and retinol concentrations between 16 and 20 gestational weeks (β=0·045; 95 % CI 0·016, 0·074) were positively associated, whereas having a smoker in the house was negatively associated (β=–0·087; 95 % CI: –0·166, –0·009). Consumption of pro-vitamin A-rich fruits by pregnant women should be encouraged. Passive smoking may play a role in decreasing vitamin A status as a proxy of smoking exposure during pregnancy.