The effect of Vitamin E supplementation on inflammatory biomarkers and oxidative stress in patients with chronic kidney disease on hemodialysis: A systematic review

Hemodialysis, along with chronic kidney disease (CKD), intensifies the inflammatory process and oxidative stress in patients undergoing treatment. In this context, Vitamin E supplementation can mitigate the deleterious effects resulting from these processes. This is a systematic review whose objective was to evaluate the effect of Vitamin E supplementation on inflammatory biomarkers and oxidative stress in patients with CKD on hemodialysis. This review was prepared according to the methodology for systematic reviews and meta-analyses (PRISMA) and the search was performed in Pubmed, Cochrane Library, Scopus and Web of Science databases. The risk of bias of the included studies was assessed with the Cochrane Risk of Bias Tool. Twelve studies developed between 2006 and 2020 were included in this review. Most of them (n= 11) used vitamin E doses ranging from 400 IU to 888 IU and the supplementation time ranged from 2 weeks to 12 months. Of all the 12 articles included, 25% (n= 3) analyzed supplementation on biomarkers of oxidative stress and 25% (n= 3) addressed these parameters simultaneously. A positive effect was observed in 58.4% of the studies (n= 7). Thus, Vitamin E supplementation can be effective in mitigating the inflammatory process and oxidative stress, however, it is worth noting that the effect depends on the dose and time of supplementation.

La hemodiálisis, junto con la enfermedad renal crónica (ERC), intensifica el proceso inflamatorio y el estrés oxidativo en los pacientes en tratamiento. En este contexto, la suplementación con vitamina E puede mitigar los efectos nocivos resultantes de estos procesos. Esta es una revisión sistemática cuyo objetivo fue evaluar el efecto de la suplementación con vitamina E sobre biomarcadores inflamatorios y estrés oxidativo en pacientes con ERC en hemodiálisis. La revisión se elaboró según la metodología para revisiones sistemáticas y metanálisis (PRISMA) y la búsqueda se realizó en las bases de datos Pubmed, Cochrane Library, Scopus y Web of Science. El riesgo de sesgo de los estudios incluidos se evaluó con la Herramienta Cochrane de Riesgo de Sesgo (Cochrane Risk of Bias Tool). En esta revisión se incluyeron doce estudios desarrollados entre 2006 y 2020. La mayoría (n= 11) utilizó dosis de vitamina E que oscilaban entre 400 UI y 888 UI y el tiempo de suplementación osciló entre 2 semanas y 12 meses. De los 12 artículos incluidos, 25% (n= 3) analizaba la suplementación en biomarcadores inflamatorios, 50% (n= 6) en biomarcadores de estrés oxidativo y 25% (n= 3) en estos parámetros simultáneamente. Se observó un efecto positivo en 58,4% de los estudios (n= 7). Por lo tanto, la suplementación con vitamina E puede ser efectiva para mitigar el proceso inflamatorio y el estrés oxidativo, sin embargo, vale la pena señalar que el efecto depende de la dosis y el tiempo de suplementación.

Serum Retinol Levels in Pregnant Adolescents and Their Relationship with Habitual Food Intake, Infection and Obstetric, Nutritional and Socioeconomic Variables.

Globally, vitamin A deficiency (VAD) affects about 19.1 million pregnant women. Its occurrence is classically associated with inadequate food intake and may also be associated with socioeconomic factors and the presence of infection. The aim of this study was to determine the factors related to serum retinol levels among pregnant teenagers. The sample consisted of 89 pregnant adolescents, from whom socioeconomic, obstetric, anthropometric, and food consumption data were collected. Serum concentrations of retinol and the supposed presence of infection were determined by high-performance liquid chromatography and C-reactive protein quantification, respectively. The serum retinol concentrations were classified according to the criteria of the World Health Organization. We adopted a 5% significance level for all statistical tests. Serum retinol levels were significantly and positively associated with sanitation (p = 0.008) and pre-gestational nutritional status (p = 0.002), and negatively with the trimester (p = 0.001). The appropriate sanitation conditions and pre-pregnancy body mass index (BMI) were shown to have a protective effect against VAD. Conversely, serum retinol levels were reduced with trimester progression, favoring VAD occurrence.

The impact of vitamin A supplementation on the immune system of vitamin A-deficient children.

BACKGROUND & AIMS: To investigate the effect of vitamin A supplementation on parameters of the immune system of vitamin A-deficient children. METHODS: The study was carried out in four phases: 1) determination of serum retinol in 631 children from 36 to 83 months of age; 2) assessment of immunological markers [immunoglobulins and complement fractions, immunophenotyping of T and B lymphocytes, and natural killer (NK) cells], blood count, and serum ferritin of 52 vitamin A-deficient children (serum retinol < 0.70 micromol/L); 3) supplementation of the 52 deficient children with 200,000 IU of vitamin A; 4) determination of serum retinol and the immunological parameters 2 months after vitamin A supplementation. RESULTS: before vitamin A supplementation, 24.0 % of the children were anemic and 4.3 %had reduced ferritin concentrations. There was no significant difference between mean values of retinol according to the presence/absence of anemia. The mean values of the humoral and cellular immunological parameters did not show a statistically significant difference before and after supplementation with vitamin A. Children with concomitant hypovitaminosis A and anemia presented a significant increase in absolute CD4 and CD8 T-cell counts after vitamin A supplementation (p < 0.05). CONCLUSION: vitamin A had an effect on the recruitment of T and B lymphocytes to the circulation of children with hypovitaminosis A and anemia.

The influence of iron, vitamin B(12), and folate levels on soluble transferrin receptor concentration in pregnant women.

BACKGROUND: Soluble transferrin receptor (sTfR) concentration is high in iron deficiency and in conditions of increased erythropoiesis. In developing countries like Brazil, pregnant women usually have concurrent iron, vitamin B(12), and folate deficiencies. This study investigated the relationship between serum sTfR concentration and iron, vitamin B(12), and folate status in pregnant women. METHODS: The concentration of the sTfR, hematocrit (Hct), hemoglobin (Hb), red blood cell (RBC) and white blood cell (WBC) counts, serum iron (SI), total iron-binding capacity (TIBC), transferrin saturation, serum ferritin, zinc protoporphyrin (ZPP), vitamin B(12), and serum and RBC folate were determined in 40 healthy pregnant women who delivered term babies. RESULTS: sTfR concentration was significantly higher when the women had iron deficiency (serum ferritin <10 microg/l, p<0.01), but there was no significant difference in sTfR concentration according to vitamin B(12), serum, and RBC folate concentrations. Women who had serum ferritin <10 microg/l also had lower vitamin B(12) values (p<0.01). There was no significant correlation between vitamin B(12) and serum folate with sTfR concentration. According to a regression analysis, sTfR concentration was associated with serum iron, serum ferritin, RBC count, and hemoglobin concentration. CONCLUSION: Iron was the only micronutrient that influenced the sTfR concentration. Vitamin B(12) and folate concentrations were probably not sufficiently low to have an impact on the sTfR concentration.