Osteoporosis refers to a group of diseases in which bone resorption outpaces bone deposit (i.e. bone loss occurs faster than bone growth). The bones become so fragile that something as simple as a hefty sneeze or stepping off a curb can cause them to break. The composition of the matrix remains normal, but overall bone mass declines, and the bones become porous and light.
Osteoporosis affects the entire skeleton, but the spongy bone of the spine is most vulnerable. For this reason, compression fractures of the vertebrae are common in people with osteoporosis. The femur, particularly its neck, is also susceptible to fracture (a broken hip).
Risk Factors for osteoporosis
Most often, osteoporosis occurs in the aged, particularly in postmenopausal women. Men can also develop the debilitating bone disorder, but woman are far more likely candidates. To put this in retrospect, 30% of American women between the ages of 60 and 70 have osteoporosis, and 70% will have it by age 80. Moreover, 30% of all Caucasian women (the most susceptible group) will experience a bone fracture due to osteoporosis.
Sex hormones (androgens in males and estrogens in females) help maintain the health and overall density of the skeleton by restraining osteoclasts (cells that resorb or degrade bone tissue) and promoting deposit of new bone. After menopause however, estrogen secretion wanes, and estrogen deficiency is strongly implicated in osteoporosis in older women.
Several other factors can contribute to osteoporosis:
- A diet poor in calcium and protein
- Smoking (reduces estrogen levels)
- Lack of exercise
- Abnormal vitamin D receptors
- Petite body type
- Hormone-related conditions such as hyperthyroidism, low blood levels of thyroid-stimulating hormone, and diabetes mellitus
Osteoporosis can develop at any age as a result of immobility. It can also occur in males who are being treated with androgen-suppressing drugs due to prostate cancer.
Osteoporosis has traditionally been treated with calcium and vitamin D supplements, weight bearing exercise (weightlifting, jogging), and hormone replacement therapy, (HRT) particularly estrogen. Frustratingly, hormone replacement therapy slows the loss of bone but doesn’t reverse it. Additionally, because of the increased risk of heart attack, stroke, and breast cancer associated with estrogen replacement therapy, its a controvertial treatment method. Although it’s not a substitue for hormone replacemnt therapy, estrogenic compounds in soy products (mainly the isoflavones daidzein and genistein) offer a good addition to some patients regimens.
Newer drugs are also available. Bisphosphonates decrease osteoclast activity and number and can partially reverse osteoporosis in the spine. Selective estrogen receptor modulators (SERMs), such as raloxifene, dubbed “estrogen light”, mimics estrogen’s beneficial bone-sparing properties without targeting the breast or uterus. Additionally, statins, which are drugs used to lower cholesterol, have an unexpected side effect of increasing bone mineral density (up to 8% over four years). The monoclonal antibody drug denosumab has been known to significantly reduce fractures in men with prostate cancer, it also improves bone density in the elderly.
How can osteoporosis be prevented (or at least delayed)? First,make sure to get enough calcium while your bones are still increasing in density (bones reach their peak density in early adulthood). Second, carbonated beverages and alcohol can leach minerals from bone and decrease bone density. You don’t have to quit drinking carbonated beverages and alcohol, just keep the above fact in mind. Lastly, get plenty of weight-bearing exercise (jogging, weight lifting, basketball, etc.) throughout life. Exercise will increase bone mass and provide a greater buffer against age-related bone loss and osteoporosis.