Causes of Osteoporosis
In my last post I produced some statistics suggesting that bone mineral density (BMD) isn’t necessarily a predictor of osteoporosis incidence and in some countries with low BMD there are also low levels of osteoporosis. In fact, the International Osteoporosis Foundation states:
“Since the clinical outcome of osteoporosis is bone fracture, attention is now increasingly focused on the identification of patients at high risk of fracture rather than the identification of people with osteoporosis as defined by BMD alone. Although osteoporosis is defined in terms of BMD and micro architectural deterioration of bone tissue, BMD is just one component of fracture risk. Accurate assessment of fracture risk should ideally take into account other proven risk factors that add information to that provided by BMD.”
Osteoporosis and fractures occur when bone reproduction cannot keep up with bone loss, a natural life long process with chronological cycles:
“a) the growth phase that occurs during childhood and adolescence; b) the maintenance phase that occurs during young to middle adulthood; c) the mid-life bone loss phase that typically occurs in adults between age 50–70; and d) the frailty phase that typically occurs in adults over age 70.” (Bone Health and Osteoporosis: A Report of the Surgeon General)
Causes of Osteoporosis
- Age: As mentioned above, beyond the age of 50 we lose more bone than we can produce, which partly explains the rise in the disease as we all live longer.
- Gender: Women are at the mercy of their hormones. Oestrogen is essential for healthy bones and after the menopause there is a permanent drop leaving women more susceptible to osteoporosis.
- Genes: If a parent had a fracture (particularly hip fracture) then your risk of fracture is increased, independent of BMD.
- Tobacco, alcohol and drugs: Smoking and heavy alcohol consumption both increase the risk of fractures which increases with age. Certain drugs will too: prolonged use of corticosteroids is the most common cause of secondary osteoporosis and the use of sedatives and antidepressants has been shown to increase risk of hip fracture. PPIs, drugs used to treat heartburn, GERD and gastric ulcers can reduce the absorption of calcium.
- Body weight/diet: Low body weight is associated with greater bone loss and increased risk of fracture. Some young female elite athletes exercise too much, eat too little and experience amenorrhea which makes them at risk of low bone mass and fractures. Low body weight in infancy determines bone mass later in life.
- Falls: Falls contribute to fractures: 90% of hip fractures result from falls and 1/3 of people over age 65 fall annually. It is often a fall that alerts you to the fact that you have osteopenia or osteoporosis.
- Inactivity: A sedentary lifestyle, reduced muscle strength, posture and balance are risk factors for developing osteoporosis and fractures later in life.
Prevention of Osteoporosis
- Start early: Ensure that you are fit and healthy during pregnancy. Supplements, including calcium, are recommended until you finish breast feeding. Ensure that your child gets a healthy, balanced diet and exercise whilst you are responsible: it is during this time that the growth phase occurs.
- Lifestyle: Limit your alcohol intake, avoid smoking and take prescription drugs minimally and responsibly. Take regular healthy levels of exercise including aerobic, strength, mobility, flexibility and balance. Over-exercising can be as bad as not exercising at all; the same advice goes for body-weight, neither over nor underweight. Get a dose of vitamin D each day by being outside for a bit. A healthy, balanced diet, high in plant foods cannot be over-emphasised, especially for women: the side effects of the menopause we suffer in the West and the early onset are not experienced by some women in parts of Africa and Japan for example and neither is osteoporosis.
Next time: Yoga for healthier bones