Phytoestmgen-containing diets may influence bone metabolism and may also modulate the effects of estrogen on bone. The present study utilized 45 female macaques which were ovariectomized and then randomized to groups receiving diets containing: 1) Casein and Lactalbumin (WLac) as the protein source (n = 12); 2) W L a c + 17~estradio(lE 2) (n=13); 3) Soy (phytoestmgen-rich) as the protein source @=lo); and 4) Soy protein+ E2 (n=lO). After 6 months, serum was collected for determination of alkaline phosphatase (ALP), acid phosphatase (ACP), tartrateresistant acid phosphatase (TRAP), uhosuhate (Pi). and calcium ICaL E2 treatment reduced serum ALP, ACP, TRAP, Pi and Ca in both diet groups. In contrast to E2 treatment, Soy diet increased serum Ca, and tended to increase. TRAP levels relative to C a s h c diet groups. Soy diet caused a significant decrease in Pi @ less than 0.01), and tended to reduce ACP @=.052) and ALP (ns), similar to the effects of E2 but to a lesser extent. These findings suggest that serum chemistries are affected differently by the phytoestrogen-rich Soy diet than by E2 treatment. No significant interactions between protein source and E2 were observed, demonstrating that Soy did not antagonize E2 effects. The mechanisms underlying these effects are not known, indicating the need for further investigations in this rapidly developing area.
