About Osteoporosis: Causes

Bone is made up mostly of minerals such as calcium. The bone in our bodies is constantly being broken down and replaced with new bone. This bone-building cycle takes about 100 days and is influenced by the hormones produced in our bodies (such as estrogen in women) as well as by the levels of calcium and vitamin D. Osteoporosis occurs when bone tissue and minerals are lost faster than the bone is replaced.

There are two main types of osteoporosis: primary and secondary.

Primary osteoporosis occurs most commonly in women after menopause. Osteoporosis affects twice as many females over the age of 70 years as males in the same age group.

Secondary osteoporosis can affect young and middle-aged people as well. It may be caused by:

  • medications such as corticosteroids (e.g., prednisone*)
  • chronic illnesses such as anorexia nervosa (a self-inflicted lack of food which leads to malnutrition)
  • too much exercise - women who exercise excessively may lose their menstrual cycle and stop the normal production of estrogen by the ovaries

Factors that may increase the risk of osteoporosis include:

A drop in estrogen after menopause. The rate of bone loss increases significantly after menopause because the ovaries stop producing estrogen, a hormone that plays a major role in the bone repair process. Female athletes and women who suffer from anorexia nervosa may also be at increased risk for osteoporosis. In both cases, the menstrual cycle is disrupted or lost and levels of estrogen in the body drop dramatically. Women who experience early menopause (before the age of 45 years) or women who have not had any children are more likely to have osteoporosis.

Family history and body type. Osteoporosis tends to run in families and the risk of this condition may be greater for individuals with elderly relatives who have had more than one bone fracture. People of European and Asian descent are most at risk. People who are thin or "small-boned" also have a higher risk of osteoporosis.

Lifestyle factors and health conditions. Lifestyle factors such as smoking and excessive drinking, taking specific medications (such as corticosteroids), and having certain diseases may also contribute to bone loss. People with type 2 diabetes are more likely to suffer a hip or shoulder fracture than those without diabetes.

Lack of exercise. Bones need to be used daily in order for them to stay healthy. People who are physically active are less at risk of developing osteoporosis, as their bones are stronger and less likely to lose strength with age. By contrast, a person who is bed-ridden or inactive for a lengthy period of time loses bone mass very quickly and is at high risk of osteoporosis.

Lack of calcium. Children, adolescents, and adults need to eat the recommended amounts of vitamins and minerals. Calcium and vitamin D are very important in the maintenance of healthy and strong bones throughout life and in the prevention of osteoporosis.

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