Effects of dietary phytoestrogens on bone markers in senile female rats

Osteoporosis has become a major public health problem. The extensive clinical trials developed through the past decade appear to rationalize the clinical utilities of medicinal plants. Of particular interest in relation to human health are the class of compounds known as phytoestrogens, which embody several groups of non-steroidal estrogens including isoflavones and lignans. The aim of this study was to assess the protective action of dietary phytoestrogens namely: flaxseed, soybeans and ginseng roots against senile osteoporosis. This study was conducted on 24 senile female rats divided into 4 groups (each of 6 rats) and 6 young female rats as control young. Both young and senile control groups were fed standard diet and the other groups were fed standard diet supplemented with either 10% flaxseed or 20% crushed soybeans or 1% ground ginseng roots for 8 weeks. Then the blood samples were collected for detecting each of serum estradiol, serum parathyroid hormone (PTH), osteocalcin, TNF-α, IL-1 α, IL-6, IL-10, 1, 25– (OH)₂ vitamin D, total calcium, ionized calcium and phosphorous level. The results revealed marked improvement in several bone markers outlined as follows: significant increase in both serum estradiol and osteocalcin level with concomitant significant decrease in PTH level was found. Significant decrease in each of serum TNF-α and the cytokines IL-1α, IL-6 and IL-10 level was detected with insignificant increase in each of serum 1, 25– (OH)₂ vitamin D, total calcium, ionized calcium and phosphorous level. In conclusion the biological effects of phytoestrogens are mostly mediated by the interaction with estrogen receptors ER's, where they may act as agonist or antagonist. Actually, phytoestrogens can prevent bone loss associated with aging and thus represent a potential natural alternative therapy for a range of hormone dependant postmenopausal symptoms. Meanwhile, these encouraging results provide new concepts for the development of effective therapeutic modalities for preserving bone mineral density in postmenopausal subjects.