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Bone mineral turnover was studied in sham and ovariectomized (ovax) retired breeder rats after 16 wk of dietary treatment. Rats were fed either a commercial rat diet (CRD) containing high calcium and cholecalciferol or egg-white diets (EWD) containing 2 g Ca/kg, 1,25-(OH)2cholecalciferol (5 μg/kg), and either 10 or 200 mg zinc/kg. In rats fed EWD, high Zn enhanced femoral Zn deposition and concentration but did not affect serum Ca levels, bone mineral content (BMC), or turnover. Serum Ca levels and BMC were greater in sham rats and there was a gain in femoral Ca and phosphorus compared with the loss ofthese minerals in ovax rats. In CRD-fed ovax rats, values for these variables were similar to those of CRD-fed shams and there was no bone mineral loss. These data suggest that ovarian function may be a prerequisite for the beneficial effects ofdiets containing 1,25-(OH)2cholecalciferol and low Ca on bone metabolism [ABSTRACT FROM AUTHOR]

Changes in seven plasma carotenoids were measured in 30 men for 11 d after ingesting a single dose of pure β-carotene or a high carotenoid vegetable. A controlled, low-carotenoid diet was fed in a crossover design. Maximum plasma concentrations of β-carotene occurred 24-48 h after dosing with β-carotene (12 or 30 mg) or carrots (270 g). A large intake of broccoli (600 g) or tomato juice (180 g) did not change any plasma carotenoids. We concluded that 1) normal subjects vary widely, three to fourfold, in efficiency of carotenoid absorption; 2) peak plasma response to a-carotene in a capsule occurs at 24-48 h; 3) a large single intake of carrots produces a small increase in plasma β-carotene but single intakes of broccoli or tomato juice do not change plasma carotenoids; and 4) plasma response to pure β-carotene is greater than the response to a similar amount of β-carotene in carrots. [ABSTRACT FROM AUTHOR]

This study was undertaken to investigate the effect of pregnancy and glucose loading on zinc metabolism. In a completely random design with repeated measures, 18 nonpregnant women, 16 early-pregnant women (13-17 wk), and 16 late-pregnant women (28-34 wk) had blood collected at 0, 30, 60, 120, and 180 mm after ingesting 100 g glucose to evaluate changes in variables of Zn nutriture. Fasting plasma Zn concentrations decreased significantly as pregnancy progressed. Late-pregnant women had significantly higher erythrocyte Zn levels and greater 24-h urinary Zn and glucose excretions. Erythrocyte Zn responses to glucose loading were unaffected by gestational age. Plasma Zn after a glucose load in nonpregnant women exhibited a curvilinear response whereas pregnant women showed no change. This lack of response by pregnant women may be related to their lower plasma Zn concentrations. Plasma Zn in pregnant women may not be as readily available to assist in glucose utilization. [ABSTRACT FROM AUTHOR]