A to Z: vitamin A and zinc, the miracle duo.

Dietary micronutrients such as vitamins and trace minerals are known modulators of host immune responses against common pathogens. In this respect, vitamin A and zinc have recently received increased attention. Several in vivo and in vitro studies suggest that vitamin A may be a critical player in the mucosal immune responses in the respiratory and gastrointestinal tracts, particularly in undernourished children. The effect may be mediated primarily by stabilization of the membrane of mucosal epithelial cells, as well as enhanced leukocyte functions. The beneficial effect of vitamin A therapy in reducing measles-associated morbidity and mortality suggests its crucial role in defenses against viral pathogens. Zinc is also known affect leukocyte functions such as phagocytosis and T-lymphocyte-mediated immune responses. However, unlike vitamin A, zinc has been investigated primarily for its effects on bacterial infections. Dietary supplementation or therapeutic treatment with vitamin A and zinc may be a cheap yet effective means of preventing or treating infections in highly susceptible populations. Additional studies, however, are required to better define the types of pathogens and the specific human populations that may benefit from such therapy.

Deficiencia de vitamina A: frecuencia y características clínicas en dos poblaciones del Estado de Chiapas / Deficiency of vitamina A: frequency and clinic characteristics in two populations in Chiapas

Introducción. La deficiencia de vitamina A ha sido bien reconocida como un problema de salud pública en el mundo. Existen pocos estudios en nuestro país acerca de la seroprevalencia de deficiencia de esta vitamina. Los objetivos de este estudio fueron: a) determinar la prevalencia de deficiencia de vitamina A en niños menores de cinco años de edad, de dos poblaciones chiapanecas, b) establecer que relación existe entre los niveles séricos de retinol con signos clínicos de deficiencia de vitamina A, estado nutricional (de acuerdo a peso y talla) e historia de hábitos nutricionales. Material y métodos. Se realizó un estudio transversal en dos en dos poblaciones, una rural y otra urbana del estado de Chiapas. El cuestionario de recolección de datos incluyó: datos antropométricos del niño, evaluación clínica de éstos y los resultados de la serología sobre retinol. Se contempló la posibilidad de administrar vitamina A (200,000 UI por dosis) a todos aquellos niños que mostraran deficiencia. Resultados. La prevalencia de hipovitaminosis A en la población estudiada fue del 25 por ciento. No existieron nihiperqueratosis ni xeroftalmia. Los datos sobre el estado nutricional revelaron la presencia de una desnutrición leve a moderada en ambas poblaciones. Conclusiones. El cálculo de la ingesta de retinol contenido en la dieta diaria, mostró una ingesta muy baja de este último, todo lo cual hace suponer que los hábitos dietéticos inadecuados pudieran ser la principal causa de la deficiencia de vitamina; por lo tanto los programas de educación nutricional son muy importantes en estas poblaciones

Effect of vitamin-A deficiency on plaque forming response of antibody producing spleen cells against Salmonella typhimurium in rats.

Plaque forming response of antibody producing spleen cells against Salmonella typhimurium was studied in vitamin-A deficient and normal rats after 3, 6, 9 and 12 days of injecting the antigen. Vitamin-A deficient rats were found to have significantly decreased (P less than 0.001) number of antibody plaque forming cells in the spleen as compared to normal rats in all cases. Serum total protein and serum Vitamin-A levels were significantly (P less than 0.001) lower in the vitamin-A deficient rats as compared to the controls and immunization caused no significant change in these parameters. The average spleen weights were increased in both the groups on immunization but this increase was comparatively more in case of the control rats.