Tuesday, November 14, 2006 - 3:00 PM

Carotenoid-Biofortified Maize Maintains Adequate Vitamin A Status in Mongolian Gerbils.

Julie A. Howe and Sherry A. Tanumihardjo. Univ of Wisconsin-Madison, 1415 Linden Dr, Madison, WI 53706

In many areas of the world, vitamin A (VA) deficiency is a major health problem.  Staple foods such as maize, rice, and wheat, are typically low in provitamin A. Recent efforts to genetically improve maize with provitamin A carotenoids, e.g., β-carotene, have been successful, but whether this approach alleviates VA deficiency is unknown. Two studies investigated the bioefficacy of provitamin A carotenoids from maize (Zea mays L.) and compared the effects of maize percentage and carotenoid content on VA status in VA-depleted Mongolian gerbils (Meriones unguiculatus).  Four near-isogenic maize lines were used to prepare 6 feeds with variable maize and carotenoid compositions. To initiate VA-deficiency, gerbils were fed a white maize VA-free diet for 4 wk prior to treatment.  In study 1, treatments (n = 10/group) included oil control, 60% high-β-carotene maize, and β-carotene or VA supplements (matched to high-β-carotene maize).  In study 2, gerbils were fed 30% or 60% orange or yellow maize diets.  After 4-wk, liver VA was determined using HPLC.  For study 1, liver VA, compared with the high β-carotene maize group, was significantly higher in the VA group (P < 0.05), lower in the control (P < 0.05), but did not differ from the β-carotene group. Bioconversion was ~1.5 mol β-carotene to 1 mol VA. Liver β-carotene content was greater in the high-β-carotene maize group compared with the β-carotene supplement (P < 0.05).  Study 2 showed an improvement in VA status with increasing β-carotene.  Vitamin A status in gerbils receiving orange maize was greater than those receiving yellow maize, regardless of percent (P < 0.05).  Biofortified maize adequately maintained VA status in this model and was as effective as β-carotene supplementation.  The contribution of β-cryptoxanthin in maize to VA is currently being evaluated.