Osteoporosis In Post Menopausal Women

Author

S. K. Mitra, Research and Technical Services The Himalaya Drug Company, India

Proceeding

1st International Conference & Exhibition on Women's Health & Asian Traditional (WHAT) Medicine

Date

23/8/2005

Keyword

osteoporosis, calcium intake, post menopousal women, sex hormone deficiency, phytoestrogens, bone mineral density

Abstract

The epidemiology of osteoporosis:  The risk of osteoporotic fracture is lower in Asia and Africa than among Caucasian women in the USA and Europe, but worldwide projections showed that it will probably increase markedly in the future. While the risk of osteoporotic fracture is lower in Asia, a cause for concern is that the average calcium intake among Asian women has been observed to be about half that of Western population groups. Calcium intake is much lower in Asia and Africa than in the United States and Europe, mainly due to the exceedingly low intake of milk and dairy products. However, although the prevalence of osteoporosis, especially hip fracture, is currently much higher in Western countries than in developing Asian countries, in the rapidly industrializing countries of Asia and other areas, the prevalence of osteoporosis is rapidly approaching the level in Western countries. Asian women historically have had lower hip fracture rates than Caucasians, yet Asians have fractures of the spine or vertebrae more often than Caucasians. By 2050, the number of hip fracture would increase three to four times higher than that at present, and over half of all hip fracture will occur in Asia. Risk factors: Up to 50% of the variation in peak bone mass may be determined genetically. Sex hormone deficiency plays a major role in development of osteoporosis. In addition, nutrition, physical activity, cigarette smoking, and alcohol consumption also affect bone mass. Modification of these risk factors is important to prevent osteoporosis and consequent fracture in future generations. Therapeutic options: Most of the drugs studied produce significant BMD increases but with significant differences regarding fracture risk reduction, especially regarding extravertebral fractures. Bisphosphonates and selective estrogen receptor modulators would constitute the first line of treatment of postmenopausal osteoporosis with previous fractures. Possible side effects, risks, treatment comfort and price in addition to the demonstrated efficacy in fracture prevention must be considered in the selection of treatment. Role of phytoestrogens- potential therapeutic agents:: The use of dietary phyto-oestrogens as a possible option for the prevention of osteoporosis has raised considerable interest because of the increased concern about the risks associated with the use of hormone-replacement therapy. Mechanism of action: Phytoestrogens have the potential to maintain bone health and delay or prevent osteoporosis. Phytoestrogens exert biphasic dose-dependent effects on osteoblasts and osteoprogenitor cells, stimulating osteogenesis at low concentrations and inhibiting osteogenesis at high concentrations. They inhibit osteoclast formation and activity. Recent data show that the balance between estrogen receptors and peroxisome proliferator-activated receptors, which are dose-dependently activated by phytoestrogens, determines their biological effects on bone. Evidence: Investigations using animal models have provided convincing evidence of major improvements in bone mass or bone turnover following soyabean feeding. Cross-sectional observations in South-East Asian populations with moderately high intakes of soyabean isoflavones (50 mg/d) have shown that women in the high quartile of intake have higher bone mineral density (BMD) and reduced bone turnover, an effect that has not been shown in populations with low average intakes. Human trials have given an indication of a possible effect on lumbar spine BMD, although they have been either short term (<6 months) or methodologically weak. Unresolved issues are: the optimal dose compatible with safety; the individual differences in response that can be related to diet and genotypes; the duration of exposure. Furthermore, there needs to be an evaluation of the relative biological effects of phyto-oestrogens other than isoflavones (lignans, resorcylic acid lactones, flavanols, coumestans) that are also present in European diets.