People with asthma tend to be at increased risk for osteoporosis, especially in the spine, for several reasons. First, anti-inflammatory medications, known as glucocorticoids, are commonly prescribed for asthma. When taken by mouth, these medications can decrease calcium absorbed from food, increase calcium lost from the kidneys, and decrease bone formation. Doses of more than 7.5 mg (milligrams) each day can cause significant bone loss, particularly during the first year of use. Corticosteroids also interfere with the production of sex hormones in both women and men, which can contribute to bone loss, and they can cause muscle weakness, which can increase the risk of falling and related fractures.
Many people with asthma think that milk and other dairy products trigger asthma attacks, although the evidence shows that this is only likely to be true if they also have a dairy allergy. This unnecessary avoidance of calcium-rich dairy products can be especially damaging for children with asthma who need calcium to build strong bones.
Because exercise often can trigger an asthma attack, many people with asthma avoid weight bearing physical activities that are known to strengthen bone. Those people who remain physically active often choose swimming as their first exercise of choice because it is less likely than other activities to trigger an asthma attack. Unfortunately, swimming does not have the same beneficial impact on bone health as weight-bearing exercises, which work the body against gravity. Weight-bearing exercises include walking, jogging, racquet sports, basketball, volleyball, aerobics, dancing, and weight training.