The adult human body contains approximately 1,200 g of calcium, about 99% of which is present in the skeleton. Bone is constantly turning over, a continuous process of formation and resorption. In children and adolescents, the rate of formation of bone mineral predominates over the rate of resorption. Once one reaches peak bone mass, sometime between the age of 20 and 30, bone formation slows down and bone resorption begins to prevail over bone formation, beginning the cycle of progressive, age-associated bone demineralization. Therefore, in normal aging, there is a gradual loss of bone. The condition of reduced bone mineral density can increase risk of fractures and affects a large proportion of the elderly in developed countries. Caucasian and Asian women typically have low peak bone densities, and therefore, are at the greatest risk of fractures in later life. It is generally accepted that obtaining enough dietary calcium throughout life can significantly decrease the risk of fractures due to reduced bone density. Among other factors, such as regular exercise, gender and race, calcium supplementation during childhood and adolescence appears to be a prerequisite for maintaining adequate bone density later in life. But even the elderly can benefit significantly from supplementation with dietary calcium.
In women, bone loss is generally accelerated following menopause. The decline in estrogen levels associated with menopause appears to put women at increased risk for declining bone density and associated fractures. Ipriflavone, derived from naturally occurring isoflavones, promotes bone density by inhibiting bone resorption. Numerous studies of postmenopausal women and individuals whose bones are showing signs of demineralization have investigated the benefits of ipriflavone on bone health. Laboratory and clinical studies have documented ipriflavoneÕs positive effect on bone density. Experts agree that ipriflavone appears to directly inhibit osteoclast activity, thereby decreasing bone resorption. Osteoclasts and osteoblasts are two primary types of bone cells. Osteoblasts, the more exterior cells, are responsible for bone mineralization. Osteoclasts, found beneath the osteoblasts, are responsible for bone resorption. When calcium levels in the blood drop, the osteoblasts change shape, allowing the osteoclasts to become exposed and release calcium from the bones to the rest of the body.
Scientists suspect ipriflavone may also stimulate osteoblast activity. Since osteoblasts are responsible for laying down new bone, an increase in osteoblast activity would result in increased bone mineralization. This suggests ipriflavone may not only inhibit the breakdown of existing bone, but also encourage the formation of new bone. Ipriflavone, together with adequate calcium and vitamin D, a key regulatory hormone for calcium and bone metabolism, offers non-estrogenic protection against excessive bone resorption. Unlike other well-known isoflavones, such as genistein found in soy foods, ipriflavone does not have estrogenic activity. Ipriflavone can be safely used in conjunction with natural phytoestrogens or with hormone replacement therapy. Furthermore, ipriflavone provides a positive effect on bone health in women for whom hormone therapies are contraindicated.