Aging Effects

Bone mass begins to reduce between the ages of 30 and 40. Osteoblast activity (bone production) begins to decline, while osteoclast activity (bone reabsorption) continues at a normal level. Once reduction begins, women lose roughly 8% of their skeletal mass, but not all parts of the skeleton are equally affected. Epiphyses (the head of the long bones), vertebrae, and the jaws reduce at a faster rate, resulting in more fragile limbs, weight reduction, and tooth loss.

The difference between normal osteopenia and the clinical condition of osteoporosis is simply a matter of degree. Because of changes in hormones, blood cell production, bone marrow content, and other aspects, bones become more fragile, breaking easily and not repairing well. Vertebrae may collapse, distorting the vertebral articulations and putting more pressure on spinal nerves, causing more pain. Dietary changes to elevate calcium levels, hormone therapies, and exercise slow, but do not prevent, the development of osteoporosis.

Chondrocytes produce a slightly different form of gelatinous compound making up the cartilage matrix. This causes increased stiffness and thickness of the joints.

Intervertebral discs shrink and, because of the compressed discs and the loss of bone mass, body height decreases, and the thoracic spine curves, resulting in kyphosis.

As muscle and skeletal mass decreases, so does the body's mineral content. This decline can be slowed or prevented by a combination of exercise and increased dietary mineral supply.

This page was updated in November 2005.