Isoflavone regulates lipid metabolism via expression of related genes in OVX rats fed on a high-fat diet.

OBJECTIVE: To investigate the effects of isoflavone on body weight, fat mass, and gene expression in relation to lipid metabolism. METHODS: Thirty-six female SD rats were ovariectomized or sham-operated and fed on a high-fat diet. Two months later, abdominal incision was made, blood was collected to separate serum, and the liver and adipose tissue were immediately collected and weighed. Some portions of these tissues were frozen in liquid nitrogen and stored at -80 degrees C. RESULTS: Ovariectomy (OVX) with a high-fat diet could induce obesity in rats, while treatment with isoflavone significantly inhibited the increase in body weight and fat mass in abdomen. Serum total cholesterol and leptin were significantly decreased in isoflavone group, compared with the OVX group. The mRNA expression of liver fatty acid synthase (FAS) in the OVX group was significantly higher than that in sham-operated group, while this difference was not observed in the isoflavone group. The mRNA expression of liver hormone-sensitive lipase (HSL) in the OVX rats tended to be lower than that in the sham-operated rats. Furthermore, a large amount of isoflavone maintained the mRNA expression at a sham level. CONCLUSION: Isoflavone may prevent obesity induced by ovariectomy with a high-fat diet, in part by modulating gene expression related to lipid metabolism.

Soybean isoflavones preserve bone mass in hindlimb-unloaded mice.

It is well known that skeletal unloading induces bone loss. It has been shown that soybean isoflavones are effective in preventing bone loss in osteoporotic animals. We investigated the ability of isoflavones to protect bone loss induced by hindlimb unloading by using a tail-suspension mouse model. Eight-week-old female mice were divided into five groups: (1) normal housed group (Normal), (2) sham unloaded group fed a control diet (Sham-UL), (3) hindlimb unloaded group fed a control diet (UL-C), (4) hindlimb unloaded group fed a 0.25% isoflavone conjugates diet (UL-ISO 0.25), and (5) hindlimb unloaded group fed a 0.5% isoflavone conjugates diet (UL-ISO 0.5). After 3 weeks, bone mineral density (BMD) of the femur was significantly decreased in UL-C, and this bone loss was prevented by isoflavone treatment. Histomorphometric analysis revealed a decrease in the cancellous bone of the distal femur in the UL-C group, and isoflavone prevented this change. Serum corticosterone increased in the UL-C group, and isoflavones inhibited the elevation. These results suggest that isoflavones might be promising food components that provide protection from bone loss and normalize stress-induced serum corticosterone during skeletal unloading.

Effects of isoflavone and exercise on BMD and fat mass in postmenopausal Japanese women: a 1-year randomized placebo-controlled trial.

UNLABELLED: The combined intervention of isoflavone intake and walking exercise over 1 year in postmenopausal Japanese women exhibited a trend for a greater effect on prevention of bone loss at the total hip and Ward's triangle regions. INTRODUCTION: The additive effects of isoflavones and exercise on bone and lipid metabolism have been shown in estrogen-deficient animals. In this study, we determined the effects of isoflavone intake, walking exercise, and their interaction on bone, fat mass, and lipid metabolism over 1 year in postmenopausal Japanese women. MATERIALS AND METHODS: A total of 136 postmenopausal women at <5 years after the onset of menopause were randomly assigned to four groups: (1) placebo, (2) walking (45 minutes/day, 3 days/week) with placebo, (3) isoflavone intake (75 mg of isoflavone conjugates/day), and (4) combination of isoflavone plus walking. BMD, fat mass, serum lipid, and serum and urinary isoflavone concentrations were assessed. RESULTS: A significant main effect of isoflavone on the reduction in trunk fat mass was obtained at 12 months. Significant main effects of walking on the reduction in fat mass in the whole body and the trunk were observed at 3, 6, and 12 months and that in the legs and arms at 6 and 12 months. Serum high-density lipoprotein (HDL)-cholesterol concentration significantly increased by 12 months after the walking and the combined intervention. After 12 months, a significant main effect of isoflavone on BMD was observed only at Ward's triangle. Walking prevented bone loss at the total hip and the Ward's triangle to significant degrees. The effect of the combined intervention on BMD at total hip and Ward's triangle regions was greater than that of either alone. No significant interaction was observed between isoflavone and walking in any measurements recorded during the study. CONCLUSIONS: Our study suggest that combined intervention of 75 mg/day of isoflavone intake and walking exercise 3 times/week for 1 year showed a trend for a greater effect on BMD at total hip and Ward's triangle regions than either alone. Intervention with isoflavone in postmenopausal Japanese women showed a modest effect on BMD compared with those in Westerners. Further studies over longer treatment duration that include assessment of BMD at various regions are necessary to ascertain the clinical significance of the combined intervention of isoflavone plus walking in postmenopausal women.

Effects of spirulina, a blue-green alga, on bone metabolism in ovariectomized rats and hindlimb-unloaded mice.

The safety and effectiveness were examined of the spirulina alga on bone metabolism in ovariectomized estrogen-deficient rats and hindlimb-unloaded mice. The dosage range was from an amount equal to that recommended in so-called health foods for humans (0.08 g/kg BW/day) to a 100-fold higher dose. The bone mineral density (BMD) of the whole femur and tibia of ovariectomized rats in the any spirulina-treated groups was not significantly different from that of the ovariectomized group, although BMD of the distal femur and proximal tibia was significantly lower in the spirulina-treated groups than in the ovariectomized group after a 6 week-experimental period. BMD of the femur and tibia was not affected by treatment with any dose of spirulina in hindlimb-unloaded mice. These results suggest that the intake of spirulina decreased BMD in the trabecular bone of rodents under estrogen-deficient conditions.