As we age, our bones become thinner and weaker and we’re more prone to fractures. For people with cystic fibrosis, this often happens at a younger age because of many factors that often come down to the poor absorption of minerals and nutrients caused by the disease.
What do normal bones look like?
Bones have a hard exterior and a honeycomb-like mesh interior. The “honeycomb” contains collagen, calcium, protein, and other minerals. Blood vessels and bone marrow run through other parts of the bone.
The holes in the honeycomb-like mesh actually make the bones stronger, just like a brick or cement block. Minerals that build bones and help keep them strong are calcium, phosphorous, magnesium and fluoride.
Our skeleton has two practical functions; it provides a framework for muscles to attach to and protects our internal organs, and it helps the body maintain calcium and phosphate levels.
As we grow, so do our bones. During childhood and adolescence this is marked and linked to puberty and growth spurts. By late adolescence we have acquired most of our adult bone minerals. There is a peak between the ages of 20 and 30, but by the age of 40 we start to lose bone mass.
Losing bone mass is normal, but the common bone conditions osteopenia and osteoporosis are characterised by an abnormal loss.
Osteopenia is a term used by doctors to describe bones that are weaker than normal, but not weak enough to called osteoporosis.
In osteoporosis the holes inside the bones become larger and the bone becomes brittle and more susceptible to fractures. There are many factors that lead to osteopenia and osteoporosis, including a lack of the minerals that build bones. Bone mineral density (BMD) is used as a measure of both conditions.
People with cystic fibrosis have trouble absorbing minerals and nutrients which puts them at a greater risk of developing osteopenia and then osteoporosis.
Bone Mineral Density (BMD)
Bone mineral density (BMD) is a measure of how much calcium and other minerals are in your bones.
BMD is measured by dual energy X-ray absorptiometry (DXA), which is like a weak x-ray. The results are an indicator of the bone mass and how strong the bones are.
Results are usually reported as a T-score and a Z-score:
- The T-score compares bone density to the peak bone density of young adults
- The Z-score compares bone density to adults of the same age
CF and bones
Low bone density in people with cystic fibrosis has a number of contributing factors.
Lung infections are common in people with CF which leads to more intense inflammation and raised levels of chemicals called cytokines in blood and sputum (mucus from the lower part of your lungs). Cytokines increase the activity of cells that break down bone.
Good nutrition plays an important role in bone health. Getting the correct balance of vitamins, mineral and protein assists in bone development and ongoing health. Because people with CF have troubles absorbing food, they generally lack a healthy balance of minerals and vitamins. This means the bones of people with CF are often weaker.
Maintaining a healthy weight is important for everyone, but it can be hard for people CF to do so. Many people with CF are underweight, which can make bones weaker.
Medication use, especially steroids, can cause rapid bone loss. Medications reduce the level of calcium absorbed from the gut, increase the amount of calcium lost through urine, decrease the number of bone-forming cells and increase bone resorption (the breakdown of bone by cells known as osteoclasts).
Low BMD has also been associated with CF-related diabetes.
Treatments for bones
Medication called bisphosphonate is required once bone strength deteriorates too far. Bisphosphonate helps strengthen the bones.
Oral bisphosphonates are taken either:
- once a day
- once a week (on the same day of the week), or
- once a month (on the same day each month)
To help your oral bisphosphonate tablet be absorbed and to avoid side effects:
- Do NOT take with food or drinks, other than water
- Swallow the tablet with a full glass of water and stand/sit upright for 30 minutes afterwards. Bisphosphonates can irritate your oesophagus (the food pipe to the stomach)
- After taking your dose you need to wait between 30 minutes and 2 hours before eating or drinking anything (other than water)
It is important you take this medication exactly the way it is recommended and always read the patient information leaflet carefully.
Intravenous (IV) bisphosphonate infusion
If you require an IV bisphosphonate infusion, it’s recommended you:
- Drink 6-8 glasses of water for a least the 3 days before the IV infusion
- Take pain medication as advised by your CF team, and let them know of any side effects
Vitamin D plays a vital role in absorbing calcium from you food, and calcium makes your bones and teeth stronger. This in turn helps prevent osteoporosis and fractures, and even helps improve your mood, protecting you from depression.
How to get vitamin D
You need about 400 – 800IU of vitamin D daily.
Sunlight is a good source of vitamin D and it’s recommended you expose your hands, face and arms to sunlight for about 6 – 8 minutes, 4 – 6 times per week (before 10am or after 2pm).
Remember to check which of your medications make your skin more likely to burn and balance the good effect of the sun’s rays with the risk of sunburn and skin cancer.
Food rich in vitamin D include:
- Breakfast cereals
- Your CF team may also advise you to take a vitamin D supplement
Calcium is the most abundant mineral in the body and plays a major role in keeping bones strong. The daily recommended amount changes with age, for adults with CF it is around 900 – 1500mg.
Foods high in calcium include:
- Milk and other dairy products
- Leafy green vegetables like kale, spinach, broccoli
- Baked and other canned beans
- Some milk, bread and cereal are fortified with calcium
- For extra calcium add 2 – 4 tablespoons of milk powder to recipes, cereal, milk, puddings, casseroles, soups etc. This will add 52mg calcium per tablespoon
- Your CF team might also suggest calcium supplements in the form of carbonate (such as Caltrate)
A high salt diet is recommended for people with CF as the disease throws out the salt and water balance in the body. However, when salt leaves the body it takes calcium with it, meaning it’s even more important for people with CF to increase their calcium intake.
What is unhealthy for bones?
Soft drinks: caffeine and phosphorous commonly found in cola drinks have been associated with bone loss. You should limit your intake of drinks and processed foods that have phosphate or phosphoric acid listed in their ingredients.
Caffeine: more than three cups of coffee a day can decrease the absorption of calcium and contribute to bone loss. Tea and soft drinks also contain caffeine, so drink in moderation.
Alcohol: heavy drinking can lead to bone loss. Australian Guidelines recommend no more than 2 standard drinks per day and no more than 4 standard drinks on any occasion
Smoking tobacco: there are many reasons not to smoke, including reduced lung function, but smokers also have a higher rate of bone disease. Get tips on how to quit at Quit Now.
Being sedentary: Exercise has many benefits, but improving bone health is high on the list. It also helps improve your mood, fitness and general well-being, leaving you in a better position to fight infections.
Teeth like bones need calcium for their health. Everyone should be brushing their teeth at least twice a day, replacing their toothbrush with every season and should see a dentist twice a year.
Because people with CF often lack sufficient calcium and other minerals, their dental health can suffer. So it’s important to take care of your teeth.
Dentists will recommend that all major dental work be done before any bisphosphonates medications are needed.