Citrusprovedbeneficial to human health in preventing cardiovascular disorders, hypertension, anemia, and several cancers, including colon, lung, skin, stomach, and breast, in animal and cell culture studies. For the first time, current study was focused to determine whether orange juice and grapefruit juice increase bone mass in an orchidectomized (ORX) rat model of osteoporosis. Thirty-six male Sprague-Dawley rats were randomly divided into four groups of 1) sham; 2) ORX; 3) ORX + orange juice (OJ); and 4) ORX + grapefruit juice (GJ). All rats were fed to the mean intake of the sham group and were provided with freshly squeezed grapefruit or orange juice for 60 days. There was a numerical improvement in femoral density with OJ and GJ compared to the ORX group. Ultimate bone strength and femoral cortical area diameter (mm) increased (
P< 0.05) with OJ and GJ compared to the ORX group. Furthermore, bone fracture withstand threshold time(s) increased ( P< 0.05) with OJ and GJ compared to the ORX group. Beneficial effects of citrus juices on bone strength could be related to its bioactive triterpene compounds and nutrient composition. Isolation of triterpenes using specific combinations of food-grade adsorbent and ion exchange resins yielded pure limonin-17-β-D-glucoside and limonin along with obacunone, nomilin, and deacetylnomilin. Identification and characterization of the isolated limonoids were performed by specific analytical techniques, such as HPLC, LC-MS, and NMR. Further studies are needed to determine the protective effects of limonoids on bone homeostasis. Funded by USDA 2001-52102-11257 and 2004-34402-14768.