We studied the effects of
whey protein (WP) from cow's milk on
calcium and bone metabolism in ovariectomized (OVX) rats. Six-week-old female Sprague-Dawley rats were ovariectomized and fed a low-
calcium diet (0.03% Ca, 0.3% P) for 4 weeks. The OVX rats were divided into three groups and subjected to two experiments: Exp. 1, Cont group (20%
casein, 0.3% Ca),
WP (1%) group (19%
casein, 1%
whey protein, 0.3% Ca) and Low-Ca group (20%
casein, 0.03% Ca); and Exp. 2, Cont group (20%
casein, 0.3% Ca),
WP (1%) group (19%
casein, 1%
whey protein, 0.3% Ca) and WP (2%) group (18%
casein, 2%
whey protein, 0.3% Ca). The rats were fed each experimental diet for 4 weeks. The final
body weight,
weight gain, food intake and food efficiency showed no significant difference between the Cont and
WP (1%, 2%) groups in Exps. 1 and 2. There were no significant differences in the
calcium balance, serum ALP or serum
calcitonin levels between the Cont and WP groups in Exp. 1. But the breaking energies of the
WP (1%, 2%) groups were higher than those of the Cont groups in Exps. 1 and 2. As for the amount of
calcium,
phosphorus and
magnesium in the femur, there were no significant differences between the Cont and
WP (1%, 2%) groups; however, the amounts of total
amino acids in the femur of the
WP (1%, 2%) groups were higher than those of the Cont groups in Exps. 1 and 2. The amounts of
proline and
hydroxyproline in the femur of the
WP (1%, 2%) groups were also higher than those of the Cont groups in Exps. 1 and 2. These data indicate that the milk
whey protein influence in OVX rats is an increase in bone
proteins such as
collagen and enhanced bone-breaking energy.