Simply stated, with osteoporosis bones become more porous, abnormally thin, with loss of the calcified architecture or calcium. We have two types of bone: compact or cortical bone, which seems solid and hard, and trabecular bone, which is spongy and lighter. The compact bone is found mainly in the shafts of our long bones such as legs and arms; trabecular bone is found in the ends of the long bones, in the spinal vertebrae, and in the heel bones, ribs, and jaw.
You may be surprised to learn that bone is not a permanent, static substance. It is a living tissue.
Old bone cells are constantly being broken down and replaced with new bone cells in a process called bone remodelling or bone formation. The continually remodelling and repairing is in response to wear and tear, mechanical stress, and to the metabolic demands placed upon them. As metabolically our bodies need to have access to the calcium and other minerals, most bone mass is built during childhood and adolescence.
During our growing years, the osteoblasts stay way ahead of the osteoclasts (bone loss), creating more bone than is destroyed. It is in early adulthood, with the proper nutrition and exercise, and good health in general, our bones not only grow larger, they grow denser.
Unless you've had a condition that depletes the bone mass, your bones continue to increase slightly in density until the age of 35. At that time, both men and women begin to lose a little up to 1% a year of their bone density. Men usually start with greater bone mass, however, so if they get osteoporosis, it usually occurs much later in life.
It's believed that our bones reach their peak density between our mid-twenties and late thirties.
For example, rapid bone loss occurs with bed rest, anorexia, mal absorption, from several diseases and medications. It is also common for the transition into menopause to be a period of rapid bone loss. With prolonged and accelerated rapid loss, compact bone becomes thinner, the trabecular bone becomes spongier, with larger holes, and the bones become weak and vulnerable to breakage.
Studies show that women who take estrogen for at least seven years cut their risk of hip fractures in half during the time they use the drug. However, once you stop the therapy, bone loss resumes at the usual accelerated rate found in early stages of menopause.
Caucasian women aged around 50 are at much more risk than men, and one half of will suffer one or another osteoporotic fracture during her lifetime, this high incidence of osteoporosis is not universal. Women in less industrialized/Westernized countries living more traditional lifestyles like the native populations of Africa and New Zealand, the Japanese and Chinese, have much lower rates of osteoporotic fracture. Unfortunately, the osteoporotic fracture rate is gradually rising in developing countries as they "modernize," changing their lifestyle, eating, and exercise patterns.
The risk factors encouraging bone breakdown are low nutrient intake, high intake of nutrient robbers like sugar, coffee, alcohol, excess sodas, phosphorus, protein, and fat; an overall acid-forming diet; drugs and medications; inactivity and a profound lack of exercise; food allergies; mal-absorption; and endocrine factors like ovary removal, low hormone levels, adrenal or thyroid weakness.