RESUMO
Nuclear factor-erythroid 2-related factor 2 (Nrf2) is an important transcription factor that activates antioxidant genes and increases detoxifying enzymes. Studies have shown that dietary compounds can activate the Nrf2 expression and improve the antioxidant response in patients with exacerbated oxidative stress, such as chronic kidney disease (CKD). We aimed to evaluate the efficacy of nutritional interventions on Nrf2 expression and phase II antioxidant enzymes in clinical trials in CKD. We searched PubMed, Lilacs, Embase, Scopus, and Cochrane Library databases of published clinical trials and the Cochrane tool was used for the quality assessment of the studies included. We reported this review according to the PRISMA and it was registered in PROSPERO (42023389619). Thirty-nine studies were included in this review; nine evaluated the Nrf2 expression and three showed an increase in its expression. Twenty-three studies found an increase in the antioxidant enzyme levels, including superoxide dismutase, catalase, and glutathione peroxidase. Moreover, a high risk of bias was found in most of the studies and high heterogeneity in the designs, type, and duration of supplementation administered. These results suggest that dietary supplementations have a promising effect on the antioxidant enzyme response, however, it is recommended that further studies should be carried out.
RESUMO
BACKGROUND: thyroid function depends on trace mineral selenium (Se), being at the active center of the iodothyronine deiodinase that catalyzes the conversion of the thyroxine (T4) to the active form of thyroid hormone, triiodothyronine (T3). Hemodialysis (HD) patients have reduced T3 levels partly due to impaired hormonal conversion that can be related to Se deficiency, a common feature in these patients. This study evaluated the effect of Brazil nuts (richest Se source) on thyroid hormone levels in HD patients. METHODS: we performed an uncontrolled intervention with 40 HD patients (53.3 ± 16.1 yrs, dialysis vintage 62.0 (8.0 - 207.0) months) that received one nut (≈5g, average 58.1 µg Se/g) per day for three months. Se plasma levels were determined by atomic absorption spectrophotometry with hydride generation and, serum T3, free T4 (FT4), TSH as well as glutathione peroxidase (GPx) activity were measured by ELISA. RESULTS: all patients were Se deficient and presented low T3 levels at baseline. After intervention, Se plasma levels (from 17.6 ± 11.6 to 153.4 ± 86.1 µg/L), GPx activity (from 33.7 ± 5.9 to 41.4 ± 11.2 nmol/min/mL), T3 (from 27.3 ± 8.8 to 50.2 ± 4.8ng/dL) and FT4 levels (0.87 ± 0.2 to 0.98 ± 0.4 ng/dL) were significantly increased (p < 0.05), while TSH levels were reduced (from 2.17 ± 1.3 to 1.96 ± 1.1 uUI/mL), but not significantly. CONCLUSION: in conclusion, increasing Se levels via Brazil nut supplementation was associated with improvement in thyroid hormone levels in HD patients, although the amount of Se given was not able to restore T3 to normal levels.
Introducción: la funcion tiroidea depende de minerales traza de selenio (Se), que esta en el centro activo de la deiodinasa yodotironina, que cataliza la conversion de la tiroxina (T4) a la forma activa de la hormona tiroidea, triyodotironina (T3). Hemodialisis (HD) de los pacientes ha reducido los niveles de T3 de los pacientes, debido en parte a la conversion hormonal alterada que puede estar relacionada con la deficiencia de Se, una caracteristica comun en estos pacientes. Este estudio evaluo el efecto de las nueces de Brasil (la mas rica fuente de Se) en los niveles de hormonas tiroideas en pacientes en HD. Métodos: se realizo una intervencion no controlada con 40 pacientes en HD (53,3 } 16,1 anos, dialisis vendimia 62,0 (8,0 - 207,0 meses)), que recibieron una nuez (≈ 5, promedio 58,1 mg Se/g) por dia durante tres meses. Determinaron los niveles plasmaticos de Se por espectrofotometria de absorcion atomica con generacion de hidruros y los niveles de T3, T4 libre (FT4), TSH en suero, asi como la actividad de la glutation peroxidasa (GPx) por ELISA. Resultados: todos los pacientes tenian niveles bajos de Se y T3 al inicio del estudio. Despues de la intervencion, los niveles plasmaticos de Se (de 17,6 } 11,6 a 153,4 } 86,1 mg/L), actividad GPx (de 33,7 } 5,9 a 41,4 } 11,2 nmol/min/ml), T3 (de 27,3 } 8,8 a 50,2 } 4,8 ng/dL) y T4L (0,87 } 0,2 a 0,98 } 0,4 ng/dL) se incrementaron significativamente (p < 0,05), mientras que los niveles de TSH se redujeron (de 2,17 } 1,3 a 1,96 } 1,1 IUU/ml), pero no de forma significativa. Conclusión: en conclusion, el aumento de los niveles de Se via suplementacion con nuez brasilena se asocia con una mejoria en los niveles de hormonas tiroideas en pacientes en HD, aunque la cantidad de Se dada no fue capaz de restablecer la T3 a los niveles normales.