Effect of selenium supplementation via Brazil nut (Bertholletia excelsa, HBK) on thyroid hormones levels in hemodialysis patients: a pilot study
Efecto de la suplementación de selenio a través de la nuez de brasil (bertholletia excelsa, hbk) en los niveles de hormonas tiroideas en pacientes de hemodiálisis: un estudio piloto
Milena Barcza Stockler-Pinto1, Juan Jesús Carrero2, Luciene de Carvalho Cardoso Weide3, Silvia Maria Franciscato Cozzolino4 and Denise Mafra1
1Cardiovascular Sciences Graduate Program, Fluminense Federal University (UFF), Niterói-RJ, Brazil.
2Divisions of Renal Medicine and Baxter Novum, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
3Medicine Faculty, Pathology Department, Federal University Fluminense (UFF), Niterói-RJ, Brazil. ]]>
4University of São Paulo (USP), Faculty of Pharmaceutical Sciences, São Paulo, Brazil.
ABSTRACT
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 mg 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.
Key words: Hemodialysis. Thyroid hormones. Selenium. Brazil nut.
RESUMEN
]]> Introduccion: 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.Palabras clave: Hemodiálisis. Hormonas tiroideas. Selenio. Nuez de Brasil.
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