Osteoporosis is one of the major age-related conditions that every woman should be conscious about by the time she reaches menopause. In osteoporosis, there is a significant reduction in bone mass and quality, making it brittle, fragile, which increases its risk of fracture. Recent studies showed that women can actually lose 5.6% bone mass with in 4 years after menopause. [1]

The existing premise of why women are especially prone to osteoporosis is not a myth. It has long been scientifically understood that the hormone estrogen, which is high in females before menopause, suppresses bone resorption. But when estrogen becomes depleted, as in menopause, bone mineral and matrix becomes rapidly lost, leading to increasing bone fragility and high risk fractures. The life-time fracture risk for any skeletal region in women older than 50 years old is 40%. [1]

There have already been many prevention and treatment options for postmenopausal osteoporosis like estrogen hormone replacement therapy, selective estrogen receptor modulators for bone (e.g. raloxifene), bisphosphonates, and calcitonin. All of these inhibit bone resorption. Estrogen replacement and raloxifene are the first-line therapies, but unfortunately, they also share the same adverse effects such as thromboembolic events and exacerbation of menopausal symptoms. Because of this, scientists are continually looking for natural products that could possibly have fewer side effects.

Recent studies suggest that plant estrogen (phytoestrogens), specifically isoflavones, could be one alternative.

• Isoflavones are natural products that could be used in the prevention and treatment of postmenopausal osteoporosis because they are structurally and functionally related to 17B-estradiol (a form of estrogen)

• Interestingly, soy foods are the most significant source of dietary isoflavones, followed by lentils, kidney beans, lima beans, broad beans, and chickenpeas. [1]

• Isoflavone content in soy products are altered during defatting, fermentation, and ethanol extraction. These processes yield lower isoflavone content. Low-fat and nonfat soymilk have significantly lower isoflavone content, while soy foods which do not undergo fermentation liker roasted soybeans and soy powder have 2-3 times more isoflavone content than the fermented foods. Baking, however, does not alter isoflavone content in soy flour.

• Most clinical studies showed that taking isoflavones from soy products have beneficial effects on bone mass density in postmenopausal women.

• Soy isoflavones are now available as supplements, but its efficacy on bone fractures and long-term safety still needs to be established by further clinical testing. Hence, up to this date, there is no precise estimate with regard to the dose of isoflavones needed to treat or prevent postmenopausal osteoporosis.

Although further clinical studies are needed to assess recommendation guidelines for the use of isoflavones, it is good to know that it is a promising alternative which could possibly replace estrogen therapy. And as a natural plant estrogen, soy isoflavones are expected to bear lesser side effects than the synthetic estrogens currently used.

Reference:
1. Aysegul Atmaca, et.al. (2008). Soy Isoflavones in the Management of Postmenopausal Osteoporosis. http://www.medscape.com/viewarticle/580688_1