STUDIES ON THE BIOAVAILABILITY OF ZINC IN HUMANS .8. PLASMA ZINC RESPONSES TO COOKED BEEF

The response of plasma zinc concentrations to oral doses of cooked beef were studied in healthy adult subjects as a prospective new model for studying dietary zinc bioavailability. The areas under the curve of change in plasma zinc, corrected for the downward drift in the fasting state, (cAUCs) for doses of 100, 200 and 300 g of cooked beef, containing 4, 8 and 12 mg intrinsic zinc, respectively, were identical, but the response to 400 g of beef with 16 mg of zinc was non-significantly greater. In 44 studies with 400 g of cooked beef, the mean cAUC was 38.9 +/- 3.8 ug/dl.h (range: -18 to 90 ug/dl.h) for the 4 h study. The corrected peak change in plasma zinc concentration was significantly correlated with the cAUC (r = 0.88, p < 0.001). On a group basis, the first and second beef-response tests in 11 subjects repeating the test on two occassions were identical, but on a individual subject bases, the test-retest reproductibility of the response was of low order. Four-hundred grams of cooked ground beef represents a feasible oral challenge for plasma zinc appearance tests of zinc bioavailability in humans, in spite of within-subject variability.