OSTEOPOROSIS, or crumbling of the bones, affects one in four Irish women, putting them at high risk of fractures, which can be fatal. Hormone Replacement Therapy prevents osteoporosis in post menopausal women, but women with breast cancer in their family are advised against it. A new Vitamin D based treatment for osteoporosis, Rocaltrol, has been launched n the Irish market, following success in Australia, Italy and Japan. Containing a "turbo charged" vitamin D analogue, it increases the absorption of calcium, thus putting women with brittle bones at much lower risk of fractures. In a study of more than 600 women, it reduced the fracture rate by one third in three years.