Volume 46 (2000) Issue 1 Pages 70-74
The effect of experimental diets with fermented soybean (natto) containing soybean extract (nijiru) on ovariectomy (OVX)-induced bone loss was investigated. Experimental diets containing either natto (46%), natto with 3.8% nijiru supplementation or natto with 9.8% nijiru were freely given to sham-operated rats or OVX rats for 3 months. Nijiru contained saponin (660μg/g of dry nijiru) and isoflavone including daidzin (770μg/g) and genistin (580μg/g) of comparatively higher concentration. OVX caused a significant reduction in the dry weight, mineral density and mineral content of the femur. The calcium content in the femoral-metaphyseal tissues was significantly reduced by OVX and these reductions were largely prevented by the feeding of natto diets with nijiru (9.8%) supplementation. This study demonstrates that the intake of natto diets supplemented with nijiru containing isoflavone and saponin has a preventive effect on OVX-induced bone loss, suggesting that it may have a role in the prevention of osteoporosis.