Dietary xylitol prevents ovariectomy induced changes of bone inorganic fraction in rats

Thirty-six 3-month-old female Wistar rats were labelled with a single intraperitoneal tetracycline injection. Twenty-four animals were subsequently ovariectomized, while the control group of 12 animals underwent sham operations. All animals received the basal Ewos R3 diet and half of the ovariectomized animals (n=12) were given an additional 5% dietary xylitol supplementation. Three months later, following the collection of blood and urine, the animals were killed by decapitation. The tibiae were detached and prepared for chemical and other studies. The weight and density of the tibiae were measured. The right tibiae were dried and pulverized for chemical analysis of calcium, phosphorus and citric acid. The total inorganic fraction was determined by ashing the powdered bone. The left tibiae were cross-sectioned at the tibio-fibular junctions for the measurement of the width of periosteally formed bone, which was identified by tetracycline fluorescence. The examination of mineral content of bone was performed by scanning electron microscopy, using an electron probe microanalytic technique. The results indicate that the supplementation of the diet with 5% xylitol had a protective effect against the loss of bone mineral after ovariectomy in the rat. This was clearly seen in tibial density and in the inorganic fraction of the bone, and in the concentrations of bone Ca and phosphorus. Ovariectomy caused a doubling in periosteal bone formation relative to the controls, whereas the growth of the periosteally formed bone was somewhat reduced following xylitol supplementation as compared with ovariectomy alone. The results support the idea that dietary xylitol after ovariectomy seems to protect against mineral loss and may support a favourable effect of dietary xylitol on the prevention of osteoporosis.