A new approach to the assessment of marginal vitamin A deficiency in children in suburban Guwahati, India: hydrolysis of retinoyl glucuronide to retinoic acid

Abstract

The objective of the present study was to determine marginal vitamin A deficiency (VAD) by testing the hydrolysis of retinoyl glucuronide (RAG) to retinoic acid (RA) in children. Previous studies in rats showed that hydrolysis occurred when rats were vitamin A deficient. Children (n 61) aged 3-18 years, were divided into two groups, I and II. Blood was collected from the children in Group I (n 19) who were not dosed with RAG. Children in Group II (n 42) were administered all-trans retinoyl glucuronide (RAG) orally, and blood was collected 4 h after the dose. All serum samples were analysed for retinoids and carotenoids. RA was detected in serum only when serum retinol was < 0.85 micromol/l. Thus, hydrolysis of RAG to RA occurred in children with VAD or marginal VAD. Serum retinol was < 0.35 micromol/l in twenty-one children, 0.35-0.7 micromol/l in twenty-three children, 0.7-0.9 micromol/l in eleven children and >1 micromol/l in six children. Mean serum retinol in sixty-one children was 0.522 (sd 0.315) micromol/l. Mean beta-carotene (0.016 (sd 0.015) micromol/l) was far below normal compared to the level of lutein (0.176 (sd 0.10) micromol/l) in sixty-one children. A low beta-carotene level might be due to a low intake of carotene but high demand for vitamin A. The RAG hydrolysis test may prove to be a useful approach for the determination of marginal VAD with no clinical or subclinical signs of VAD. High prevalence of VAD amongst certain communities in Assam cannot be ruled out.