Fructooligosaccharides (FOS) stimulate the growth of bifidobacteria, which cleave isoflavone conjugates to yield the corresponding aglycones and metabolites. In a previous study, FOS modified the absorption and enterohepatic recirculation of isoflavones in rats. In the present study, we determined the effect of the combination of dietary FOS and isoflavone conjugates on bone mass in ovariectomized (OVX) and surgical control mice. After undergoing OVX or sham operation, female ddY mice (8 wk old, n = 64) were randomly assigned to four groups: a purified control diet (AIN-93G) group, a FOS diet (AIN-93G + 5% FOS) group, an isoflavone diet (AIN-93G + 0.2% isoflavone conjugates) group, or a FOS and isoflavone diet (AIN-93G + 5% FOS + 0.2% isoflavone conjugates) group. After 6 wk, the mice were killed and the blood and femora were sampled immediately. In OVX mice, both isoflavone conjugates and FOS prevented femoral bone loss. An additive effect of dietary isoflavone conjugates and FOS was observed by dual-energy X-ray absorptiometry in the distal part of the femur and in trabecular bone, by peripheral quantitative computed tomography. Moreover, FOS increased cecal beta-glucosidase activity and equol production from daidzein in both OVX and surgical control mice fed isoflavone conjugates. These results suggest that FOS increase the bioavailability of isoflavones, leading to cooperative effects in the prevention of osteopenia in OVX mice.

We reported that genistein, a soybean isoflavone, prevents bone loss caused by estrogen deficiency, without undesirable effects on the uterus. In this study, we examined cooperative effects of genistein administration and running exercise on bone mass in ovariectomized (OVX) mice. Female mice aged 7 weeks were either sham-operated or OVX and divided into six groups: (1) sham; (2) OVX; (3) OVX, treated with genistein at a submaximal dose (0.4 mg/day) subcutaneously (G); (4) OVX, exercised on a treadmill daily for 30 minutes/day at 12 m/minute on a 10°uphill slope (Ex); (5) OVX, given genistein and exercised (ExG); and (6) OVX, treated with 17␤-estradiol (0.03 g/day) in the same manner as genistein (E 2 ). Four weeks after intervention, bone mass was estimated by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Bone mineral density (BMD) of the whole femur measured by DXA was higher in both the G and the Ex groups than in the OVX group. Furthermore, BMD in the ExG group was significantly higher than that in the groups receiving either intervention alone. Bone area in distal region of the femur was significantly higher in Ex and ExG groups as compared with those in the OVX and G groups. pQCT analysis showed that the cross-sectional areas (CSAs) and periosteum perimeter at midshaft of the femur did not differ in the sham and OVX groups but were significantly higher in Ex and ExG groups. Histomorphometric analysis showed that bone formation rate/bone surface (BFR/BS) was significantly higher in both Ex and ExG groups as compared with that in non-exercised groups. The bone volume (BV/TV) in the distal femoral cancellous bone was lower in the OVX than that in the sham group, and it was restored completely in the ExG group, as in the E 2 group. Thickness of the trabecular bone (Tb.Th) was higher in Ex and ExG groups than that in the OVX and G groups. These results indicate that the combined intervention of moderate exercise and the submaximal dose of genistein administration show a cooperative effect in preventing bone loss in OVX mice.

There is evidence that estrogen plays an important role in skeletal tissue in males as well as females. We have reported that phytoestrogens, such as genistein, selectively act on bone and exhibit cooperative effects on bone mass when combined with exercise in ovariectomized mice. In this study, we examined whether both interventions exhibit cooperative effects on bone loss in androgen-deficient mice similar to those in estrogen-deficient mice. Male mice aged 7 wk were either sham operated or orchidectomized (ORX) and divided into six groups: 1) sham; 2) ORX; 3) ORX and treated with genistein (0.4 mg/day) subcutaneously; 4) ORX, exercised on a treadmill daily for 30 min/day at 12 m/min; 5) ORX, given genistein, and exercised (ORX+ExG); and 6) ORX and treated with 17beta-estradiol (E(2)). Four weeks after the intervention, seminal vesicle weight strikingly decreased in ORX mice, and it was not affected by administration of genistein or E(2). Bone mineral density of whole femur was significantly reduced by ORX, and bone loss was prevented by the combined intervention. Histomorphometric analysis showed that bone volume and trabecular thickness in the distal femoral cancellous bone were significantly lower in the ORX group than in the Sham group, and they were completely restored in the ORX+ExG group, as in the ORX with E(2) group. These results indicate that the combined intervention of moderate exercise and a low dose of genistein administration shows an additive effect in preventing bone loss in ORX mice similar to that in ovariectomized mice.

Dietary short-chain fructooligosaccharides (Sc-FOS) stimulate absorption of calcium and magnesium in the large intestine of rats. In this study, we examined whether Sc-FOS stimulate iron absorption in the large intestine by monitoring recovery from anemia in gastrectomized rats, with or without cecectomy. The rats were divided into four groups, i.e., sham-operated (Sham), gastrectomized only (GX), cecectomized only (CX) and both gastrectomized and cecectomized (GCX). Half of the rats in each group were fed a control diet (AIN-93G) and the other half were fed a Sc-FOS-containing diet (75 g/kg diet) for 28 d. Hematocrit (Ht) and hemoglobin concentration (Hb) were measured at the start, and on d 14 and 28 after the start of feeding. On the final day of the study, total blood was collected. Gastrectomy significantly decreased Ht and Hb, but cecectomy did not influence these variables. Dietary Sc-FOS prevented the decrease in Ht and Hb significantly. In the gastrectomized rats, the effectiveness of Sc-FOS in preventing postgastrectomy anemia was significantly diminished by cecectomy. These results suggest that the effect of Sc-FOS in increasing absorption of iron in gastrectomized rats takes place in part in the cecum. The cecum plays an important role in the mechanism by which Sc-FOS prevent postgastrectomy anemia.

No abstract