Impaired bioavailability of vitamin A in adults and children with persistent diarrhoea in Zambia.
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.


OBJECTIVE
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 micromol/L, interquartile range 0.21-0.56) than controls (median 1.16 micromol/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 micromol/L, interquartile range 0.35-0.77) did not differ significantly from that observed in HIV seronegative controls (median 0.35 micromol/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 micromol/L, interquartile range 0.04-0.35) and in children (median 0.11 micromol/L, interquartile range 0.04-0.46) than in men without diarrhoea (median 0.44 micromol/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.
Kelly
P
P
Department of Adult and Paediatric Gastroenterology, St Bartholomew's and Royal London School of Medicine and Dentistry, London, UK. mpkelly@mds.qmw.ac.uk
Musuku
J
J
Kafwembe
E
E
Libby
G
G
Zulu
I
I
Murphy
J
J
Farthing
M J
MJ
D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D002675:Child, Preschool; D003967:Diarrhea / Q000150:complications* / Q000188:drug therapy; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D014801:Vitamin A / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D015024:Zambia
D014801:Vitamin A