Impaired Bioavailability of Vitamin A in Adults and Children with Persistent Diarrhoea in Zambia
This source preferred by Jane Murphy
Authors: Kelly, P., Musuku, J., Kafwembe, E., Libby, G., Zulu, I., Murphy, J.L. and Farthing, M.J.G.
Journal: Alimentary Pharmacology & Therapeutics
Background: We have previously demonstrated a strong relationship between low serum retinol concentration and mortality in Zambian AIDS patients with diarrhoea, but were unable to detect any benefit from oral micronutrient supplementation.
Aim: To test the hypothesis that this is related to impaired availability of vitamin A, we analysed serum retinol concentration changes over 6 h following oral mega-dose therapy (60, 120 or 180 mg retinol).
Methods: Twenty-four men without diarrhoea, 15 adults with persistent diarrhoea and 11 children (six girls, five boys) with persistent diarrhoea were studied.
Results: Men with persistent diarrhoea had lower baseline serum retinol concentrations (median 0.39 μmol/L, interquartile range 0.21–0.56) than controls (median 1.16 μmol/L, interquartile range 0.84–1.47; P=0.0003). After 60 mg retinol, the rise in serum retinol in HIV seropositive controls (median 0.63 μmol/L, interquartile range 0.35–0.77) did not differ significantly from that observed in HIV seronegative controls (median 0.35 μmol/L, interquartile range – 0.04–0.56; P=0.20). Increasing the dose to 120 mg or 180 mg retinol did not enhance the increase in serum retinol concentration. The increase in serum retinol was less in adults with persistent diarrhoea (median 0.25 μmol/L, interquartile range 0.04–0.35) and in children (median 0.11 μmol/L, interquartile range 0.04–0.46) than in men without diarrhoea (median 0.44 μmol/L, interquartile range 0.26–0.74; P=0.03). Adults and children with diarrhoea had greater losses of retinol in urine over a 24-h period than controls, but less than 1% of the ingested dose was excreted.
Conclusions: These results suggest that persistent diarrhoea in this population is associated with reduced bioavailability of retinol. Further work is required to determine the metabolic fate of therapeutic doses of retinol and to determine appropriate replacement strategies for HIV infected individuals.