Cassava with enhanced o-carotene maintains adequate vitamin A status in Mongolian gerbils (Meriones unguiculatus) despite substantial cis-isomer content

摘要

Efforts to increase o-carotene in cassava have been successful, but the ability of high-o-carotene cassava to prevent vitamin A deficiency has not been determined. Two studies investigated the bioefficacy of provitamin A in cassava and compared the effects of carotenoid content and variety on vitamin A status in vitamin A-depleted Mongolian gerbils (Meriones unguiculatus). Gerbils were fed a vitamin A-free diet 4 weeks prior to treatment. In Expt 1, treatments (ten gerbils per group) included 45 % high-o-carotene cassava, o-carotene and vitamin A supplements (intake matched to high-o-carotene cassava group), and oil control. In Expt 2, gerbils were fed cassava feeds with 1p"8 or 4p"3 nmol provitamin A/g prepared with two varieties. Gerbils were killed after 4 weeks. For Expt 1, liver vitamin A was higher (P < 0p"05) in the vitamin A (1p"45 (sd 0p"23) omol/liver), lower in the control (0p"43 (sd 0p"10) omol/liver), but did not differ from the o-carotene group (0p"77 (sd 0p"12) omol/liver) when compared with the high-o-carotene cassava group (0p"69 (sd 0p"20) omol/liver). The bioconversion factor was 3p"7 og o-carotene to 1 og retinol (2 mol:1 mol), despite 48 % cis-o-carotene [(Z)-o-carotene] composition in cassava. In Expt 2, cassava feed with 4p"3 nmol provitamin A/g maintained vitamin A status. No effect of cassava variety was observed. Serum retinol concentrations did not differ. o-Carotene was detected in livers of gerbils receiving cassava and supplements, but the cis-to-trans ratio in liver differed from intake. Biofortified cassava adequately maintained vitamin A status and was as efficacious as o-carotene supplementation in the gerbil model.