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

摘要

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