Effect of the supplementation of dietary rich phytoestrogens in altering the vitamin D levels in diet induced osteoporotic rat model

Abstract

Plant-derived estrogen-like compounds such as isoflavones (IF) especially daidzein and genistein are said to be preserving the bone in the osteoporotic conditions. However, it is not known whether a combination of IF and calcium (Ca) supplementation attenuates losses in bone mass and prevents the loss of vitamin D (VD). The present study addresses the role of phytoestrogens (PE) and Ca supplementation in low Ca and low VD diet induced osteoporosis (OSP). Cowpea (CP) which has high amount of the IF was selected to study its effect on diet induced osteoporotic conditions. Female weanling WNIN rats (total of 68) were divided into five groups and fed for five weeks on semisynthetic diet with low Ca (0.15%) and low VD (0.1 IU/day/rat) in combination with low (10 mg/kg) or high (25 mg/kg) concentrations of PEs derived from CPIF. The study groups are: (I) normal Ca(0.47%) and normal VD (25 IU/day/rat), (II) low Ca + low VD, (III) low Ca + low VD + low CPIF (10 mg/kg diet), (IV) low Ca + low VD + high CPIF (25 mg/kg diet) and (V) low Ca + low VD + 17-(-estradiol (3.2 mg/kg diet). After the development of OSP the group II was subgrouped into: (SG I) continued on low Ca + VD, (SG II) low CPIF, (SG III) high CPIF, (SG IV) 17-β-estradiol and (SG V) normal Ca and VD. Serum 25-VD levels were in the range of 14–38 ng/ml in groups I, III, IV and V, where as the values were very low in the group II (5.8 ng/ml). These were partially reversed upon supplementation of CPIF. The results correlated with altered Ca levels, body weight, bone mineral density and content and other related biochemical parameters. The paper further explains the possibility of protective and therapeutic role of VD in the presence of CPIF in osteoporotic health manifestations.