Lactose-induced diarrhea increases oxidative stress and it is more severe in rats deficient in vitamin E.

Diarrhea is the disease with high incidence in the world and causes infant mortality and malnutrition in the developing world. This justifies the study of nutrition and diarrhea. Due to ethical and financial considerations it is difficult to study nutrition and diarrhea in children thus animal models have become a convenient alternative. In previous studies it was shown that lactose induced diarrhea in rats was associated with a reduction in tissue levels of vitamin E and also with evidence of an inflammatory response of the intestine. Accordingly, in this study, in order to determine the effect of this type of diarrhea on the level of oxidative stress, diarrhea was induced in vitamin E sufficient and deficient rats. The results showed that after 23 days the tissue concentration of vitamin E decreased in all the rats with diarrhea but this reduction was substantially greater in the vitamin E deficient group. Moreover, diarrhea was 60% more severe in the vitamin E deficient rats than in the vitamin E sufficient group that also had diarrhea. Both diarrhea and vitamin E deficiency altered malonaldehyde and superoxide dismutase levels in various tissues. However, the most outstanding changes associated with diarrhea were a 100% increment in plasma malonaldehyde and erythrocyte superoxide dismutase activities which were 8 to 11 times higher than those seen in the rats without diarrhea. These non-invasive changes correlated well with the severity of diarrhea. The study shows that vitamin E deficiency results in diarrheas which are more severe and that lactose induced diarrhea is associated with higher levels of oxidative stress.