The bio-availability of vitamin A in adults and children with persistent diarrhoea in Zambia

HIV infection has had a major impact on the health of the Zambian population. Micronutrient deficiencies are common in people with AIDS, and include Vitamin A, Vitamin E, Folic Acid, Zinc and Selenium deficiencies.There is a strong relationship between low serum retinol concentration and mortality in Zambian AIDS patients with diarrhoea. In order to understand the above relationship, serum retinol concentration changes over 6 hours following oral mega-dose therapy (60,120 or 180 mg retinol) were analysed.The study was done in two phases. In phase 1, it was demonstrated that absorption of retinol was not delayed at 6 hours after administration of 60 mg of retinol in both diarrhoeal patients and controls (patients without diarrhoea).In phase 2, we studied a total of fifty patients that included 24 adults without diarrhoea, 15 adults with persistent diarrhoea and 1I children, 6 girls and 5 boys with persistent diarrhoea.We did not include women in the study because of the teratogenicity of Vitamin A. Lower baseline serum retinol levels (medium 0.29 mmo/lL, interquartile range 0.21 -0.56) were found in 24 adults with persistent diarrhoea than controls (1.6, 0.84 - 1.47; p = 0.003). After administering 60 mg retinol, it was noted that the rise in serum retinol in HIV seropositive controls (0.63, 0.35 - 0.77) did not differ significantly from that observed in HIV seronegative controls (0.35, 0.04 - 0.56; p = 0.20)
After administering a mega dose of 120 mg or 180 mg. no significant rise in serum retinol concentration was noted in adults without diarrhoea. However, there was significant rise of retinol in adults without diarrhoea (0.44. 0.25 -0.74: p = 0.03) when compared to adults with persistent diarrhoea (0.25. 0.04 - 0.35 mg> and in children with persistent diarrhoea (0.11. 0.04 - 0.46).Patients with persistent diarrhoea lost large amounts of retinol in urine over a 24 hour period than controls though less than 1% of the ingested dose.Further work is required to determine physiological and metabolic fate of therapeutic doses of retinol since this study confirms that persistent diarrhoea is associated with reduced bio-availability of retinol.