• Journal of Nutrition and Health
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• v.26 no.8
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• pp.915-924
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• 1993

To study the effect of menopause and dietary protein level on Ca metabolism, ovariectomy (OVAX) and sham operations were performed in 16-week old female rats. Each treatment group was fed for 16 weeks either 5%(L) or 50%(H) casein diets, forming SH, SL, OH, OL groups. High protein groups(SH, OH) showed higher Ca and hydroxyproline excretion in urine. Urinay hydroxyproline was also higher in OVAX, which tells the possibility of increased bone resorption by OVAX and by high dietary protein. At 16th wee, however, urinary Ca and hydroxyproline of SH caught up with OH group, whereas those of OL remained higher than SL. Therefore it seems that high dietary protein overrides the effect of OVAX with time. Urnary protein measured at 8th week was higher in high protein groups, especially in OH. GFR was not differ significantly among groups at 8th week. At 16th week, however, high protein groups showed twice the GFR value of low protein groups. Therefore the increase of urinary Ca and hydroxyproline in SH and OH groups can be explained partly by the increased GFR. The tendency of increased GFR and urinary excretion of protein, Ca, and hydroxyproline was most obvious in OH group. It seems that the effect of high protein diet is likely to accelerated by ovariectomy. The effect of Ovax and dietary protein on the composition of femur, scapular, and lumbar bones, was not pronounced. However, when only the high protein groups were compared, OVAX resulted in the reduction of bone weight, ash and Ca contents, especially in femur. The reason that was no significant effect on bone might be due to the short experimental period to induce that was no significant effect on bone might be due to the short experimental period to induce the changes on bone composition and dietary Ca content used in this experiment may have been high enough to prevent bone loss.

• Journal of Nutrition and Health
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• v.31 no.4
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• pp.716-728
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• 1998

To investigate the effect of dietary Ca levels on metabolic changes of Ca and skeleton in postmenopausal women, 10-month-old ovariectomized female rats were compared with 2 month old rats. The rats were fed either 0.2% or 1.2% Ca diets for 16 weeks. Food intake and weight gain as higher in rats fed high Ca diets and in ovariectomized rats. Apparent Ca absorption as higher, and Ca balance was lower in the low Ca groups. Vertebrae density was higher in old rats or those fed a high Ca diets. The old rats and ovariectomized rats showed decreased bone formation, increased bone resorption and kidney function deterioration resulting in increased urinary Ca excretion. Contradictory to the above observation, old rats and ovariectomized rats still showed higher bone mass and bone ash content. Therefore aging was not fully onging in 10-month-old rats. Bone weights, mineral contents, and mineral/wt ratio were lower in ovariectomized rats. Dietary Ca level did not affect urinary Ca excretion, urinary protein excretion, GFR, serum alkaline phosphatase, or urinary hydroxyporline excretion. This means that dietary Ca level did not influence kidney function or bone turnover. However Ca content and the ash content of femur, 4th vertebra, and scapula were increased in high Ca groups. Therefore, it is considered that decreased bone formation and accelerated bone resorption may account for the increased osteoporotic risk in women in menopause after middle age. However, Ca metabolism can be improved and bone components can be maintained if Ca is supplemented.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.657-661
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• 2001

Osteoporosis that is associated with ovarian hormone deficiency following menopause (postmenopausal osteoporosis) is by far the most common cause of age-related bone loss. Isoflavone has been reported as a natural substance that possibly minimizes bone loss in postmenopausal women. This study was conducted to investigate the preventing, treating effects of isoflavone on bone loss in ovariectomized rats. 120 Sprague Dawley rats of 13 week-old were devided into 2 groups, a treatment group and prevention group. Each group was consisted of six subgroups; control (CON), sham operated (SH) or ovariectomized (OVX) and isoflavone supplemented goups: OVX+0.25mg isoflavone/kg diet (OL), OVX+0.8mg isoflavone/kg diet(OM) and OVX+2.5mg isoflavone/kg diet(OH). to study the preventing effects of isoflavone on bone loss, OL, OM and OH groups were fed with isoflavone from 4 days after ovariectomization. Treating effects of isoflavone on bone metabolism were investigated with OL, OM, OH groups supplemented with isoflavone from 8 weeks after ovariectomization. Isoflavone supplementation continued for 8 weeks. At 8 weeks after ovariectomization significant increase in alkaline phosphatase occurred comparing with CON and SH group. By isoflavone supplementation from 4 days after ovariectomy alkaline phosphatase and urinary hydroxyproline were lowered and bone mineral density, bone strength of the femur and tibia and bone dry weight were slightly enhanced with no significant difference. Isoflavone supplemented group at the level of 0.8mg/kg diet (OM group) had significantly lower serum alkaline phosphatase, urinary hydroxyproline, and higher strength of femur than OVX group. Groups with isoflavone supplementation fro 8 weeks after ovariectomy had lower level of serum alkaline phosphatase, urinary hydroxyproline than OVX group. Bone mineral density, bone dry weight and bone strength of the femur and tibia were slightly enhanced by isoflavone supplementation. However there was no significanct difference between OVS ad isoflavone supplementation groups. The results suggest that isoflavone might have potential role for preventing postmenopausal bone loss. Isoflavone supplementation at early stage of postemenopause may be beneficial to age-related bone health.