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MENOPAUSE AND OSTEOPOROSIS (3)
Author, Nita Bishop, Clinical Herbalist
The Isoflavones, Ipriflavone and SERMs
Are all estrogens created the same? What is a phytoestrogen? There are over 300 species of plants that have some degree of demonstrable estrogen activity. A phytoestrogen (plant estrogen) binds to estrogen receptors and elicits a cellular response. This response is of lesser amplitude than estrogen due to the fact that the phytoestrogen binds to the estrogen receptor for a shorter duration of time than does the endogenous hormone. The development of a recent term, SERMs (selective estrogen receptor modulators) concerns itself with just this type of question. SERMs are compounds (such as tamoxifen and raloxifene) that act like estrogen on some levels, but do not adversely affect breast and uterine tissue. So depending upon the tissue in question, estrogenic or anti-estrogenic effects can be elucidated. Some experts consider isoflavones (from soybeans) as natural SERMs. There is no question that phytoestrogens, such as isoflavones, are not the same biochemically as the conjugated equine estrogens. Independent studies have shown that the isoflavones genistein and daidzein inhibited the growth of tumors in breast cancer cells. However, more research is needed before we can accurately characterize the effects of isoflavones.
Ipriflavone: The Best of Both Worlds
Ipriflavone, (IP) is a slightly modified, synthetic derivative of naturally occurring isoflavones, and is a well researched and effective supplement. Since the mid to late 1980s, ipriflavone has been an approved therapeutic agent for the prevention and treatment of osteoporosis in Europe and Japan. As of 1989, it has been approved for this purpose in 21 countries. In the United States it is available over-the-counter as a dietary supplement.
Several published studies have demonstrated that IP can prevent bone loss in postmenopausal women with low bone mass. Gambacciani and colleagues concluded that the standard dose of IP (600 mg per day) had the same positive effect on bone turnover as using IP with a lower dose of conjugated estrogen (0.3 mg/day).
Results of the Ipriflavone Multicenter European Fracture Study (IMEFS) are expected to be released soon. A total of 460 women from four European centers were recruited for this randomized, double-blind, placebo-controlled, parallel-group, three-year study assessing the effect of ipriflavone on fracture rates.
Currently, Douglas Laboratories is conducting a clinical trial on an ipriflavone-containing supplement. Postmenopausal women who are not currently receiving hormone replacement therapy were randomized to receive either a product containing ipriflavone and calcium, or a placebo for three months. A specific marker in the urine that indicates the amount of bone breakdown taking place (NTx, see below) will be measured before and after supplementation. Changes in this marker of bone breakdown will help to give further insight as to the usefulness of ipriflavone. Results from this study should be available in the spring.
What tests are effective in assessing BMD (bone mass density)?
The Achilles (DXA bone scan) measures baseline bone density using an ultrasonometer resonance scan. It gives the physician a fixed picture of bone density at a place in time when the test is performed. Bone density is a completely dynamic process, and bone formation/ resorption is a constantly shifting process within the body. A good marker to measure this dynamic process is the Type I collagen which accounts for more than 90% of the organic matrix of bone. Type I collagen is synthesized primarily in the bone. During renewal of the skeleton, Type I collagen is degraded, and small peptide fragments are excreted into the bloodstream, and following renal excretion, into the urine.
The newer N-Telopeptide test (often referred to as NTx in the literature) measures the degradation products from the N-terminal telopeptide region of type I collagen, thus providing a more dynamic measurement of bone turnover. Many physicians will use these two tests in combination to monitor the success of their proactive patient therapies.
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