Bioconversion of plant carotenoids to vitamin A in Filipino school-aged children varies inversely with vitamin A status

Background: It is important to understand the factors affecting strategies to improve the vitamin A status of populations. We reported previously that a 3-d deuterated-retinol-dilution (DRD) procedure might be used to indicat e total body stores of vitamin A, Objective: We studied the ability of 3-d DRD to detect changes in the body pool size of vitamin A and the effect of vitamin A status on the bioconvers ion of plant carotenoids to vitamin A. Design: Two separate, unrelated studies were conducted in 7-13-y-old childr en with poor or marginal serum retinol concentrations (0.32-0.93 mu mol/L) by feeding them controlled diets daily for 5 d/wk for 12 wk, after treatmen t with an anthelmintic drug. In school 1 (n = 27), lunch and 2 snacks that were provided at school contained 2258 retinol equivalents/d (mostly from o range fruit and vegetables) and 5.3 MJ/d from 33 g fat, 37 g protein, and 2 09 g carbohydrates; in school 2 (n = 25), 2 snacks provided 2.5 MJ/d from 9 .4 g far, 9.6 g protein, and 119 g carbohydrates, but no carotenes. Results: In school 1, mean serum beta-carotene increased from 0.12 to 0.62 mu mol/L (P = 0.0001) and serum retinol increased from 0.68 to 1.06 mu mol/ L (P = 0.0001). In school 2, serum beta-carotene increased from 0.06 to 0.1 1 mu mol/L (P = 0.0001) and serum retinol increased from 0.66 to 0.86 mu mo l/L (P = 0.0001). In school 1, but not school 2, improvement in serum retin ol varied inversely with baseline retinol (r = -0.38, P = 0.048). In both s chools, 3-d DRD showed reductions in the ratio of serum deuterated to nonde uterated retinol (D:H retinol) postintervention, denoting improvements in v itamin A status; the higher D:H retinol tie, the poorer the status) at base line, the greater the reduction in D:H retinol postintervention (school 1: r = -0.99, P = 0.0001; school 2: r = -0.89, P = 0.0001). Conclusions: Three-day DRD can detect changes in the body pool size of vita min A, although a predictive equation to quantitate total body stores of vi tamin A with the use of 3-d data needs to be developed. Bioconversion of pl ant carotenoids to vitamin A varies inversely with vitamin A status; improv ement in status after dietary interventions is strongly influenced by total body stores of vitamin A and is influenced little or not at all by serum r etinol.