Zinc and iron bioavailability of genetically modified soybeans in rats

The aim of this work was to evaluate zinc and iron bioavailability of UFV-116, a new variety without 2 lipoxygenases, with better taste and flavor than a commercial variety OCEPAR 19, containing all 3 isozymes. To evaluate zinc absorption using 65Zn whole body retention and femur 65Zn uptake, rats were given 3 g of a 65ZnCl2 labeled test meal (0.25 microCi). The 2 varieties were tested at the level of 9 and 30 ppm of zinc as defatted soy flour. Two other groups (control) received egg white as source of protein and ZnS04.H20 as the zinc source. To evaluate iron absorption, using 59Fe whole body retention, animals were given a 3 g 59FeCl3 labeled test meal (0.2 microCi). The 2 varieties were tested at 12 and 25 ppm iron as defatted soy flour. Whole fat soy flour of variety 1 (UFV-116) was higher (P0.05) in Ca, K, Mg, phytic acid, and oxalate than variety 2 (OCEPAR-19). No difference was observed among the soybean varieties (P0.05) for femur 65Zn retention, at different levels of zinc. However, whole body retention was lower (P0.05) for UFV-116 than for OCEPAR-19. Femur 65Zn uptake was correlated with the whole body retention; however, whole body retention was more sensitive. Whole body 59Fe retention from UFV-116 was lower (P0.05) than from OCEPAR-19. Zinc and iron bioavailability was lower for UFV-116, possibly due to its higher content of antinutrient factors, especially phytate.