ASSESSMENT OF ZINC BIOAVAILABILITY - STUDIES IN RATS ON ZINC-ABSORPTION FROM WHEAT USING RADIO-ISOTOPES AND STABLE-ISOTOPES

Absorption from wheat intrinsically and extrinsically labelled with Zn -67 and extrinsically labelled with Zn-65 was measured from Zn-67 faec al excretion and Zn-65 whole-body retention in rats. There were signif icant differences between the extrinsically- and intrinsically-labelle d Zn-67 (P < 0.001), but not between the extrinsically-labelled Zn-65 and intrinsically-labelled Zn-67. The effect of chicken meat on the ab sorption of Zn from intrinsically-labelled wheat was also studied in t he rat. Mean Zn absorption from wheat and chicken meat fed separately was 18.5 and 68.2% respectively, and from a mixture of the two contain ing the same level of Zn was 50.1%. The apparent absorption of Zn from the composite meal was significantly higher than predicted from the r esults of the foods on their own (P < 0.001).