Milk consumption and zinc retention in postmenopausal women

We measured intestinal 65Zn absorption and whole-body retention in postmenopausal women following a meal extrinsically labeled with 65Zn. The meal was consumed with 200 mL of milk or with a calcium phosphate supplement. Fifteen elderly (mean age 69) subjects were studied during three 12-d experimental periods in which they were fed either a basal diet containing 16 mg Zn or the basal diet supplemented either with 400 mL of milk or with dibasic calcium phosphate supplements containing an equivalent amount of calcium (468 mg) and phosphorus (360 mg). Measurements of fractional zinc absorption were made in 9 of the 15 subjects by a dual-isotope technique using 65Zn and 51Cr (as nonabsorbable fecal markers). Fractional zinc absorption was 0.22 +/- 0.06 (mean +/- SEM) after the standard meal, 0.23 +/- 0.06 with added milk and 0.22 +/- 0.03% with the added calcium phosphate supplement. The corresponding values for 65Zn retention in 15 subjects 12 d after dosing were 0.10 +/- 0.01% for all treatments. No significant effect of milk or calcium phosphate supplementation was observed on either 65Zn absorption or retention. We conclude that increased milk consumption with meals has no detrimental consequences on zinc nutriture in elderly women.