Page 2 2011 Winter
Your bone health's connected to your...
Do you take your skeleton for granted? CEO of Osteoporosis Australia, Shelley Evans, says "Osteoporosis is widespread and extremely underdiagnosed. More than 2 million Australians have osteoporosis – this is expected to increase to more than 3 million by 2021." Fortunately, there's a lot you can do to keep your bones healthy and prevent osteoporosis.
What is osteoporosis?
Osteoporosis is a condition characterised by fragile, brittle bones. It occurs when bones lose minerals, like calcium, more quickly than the body can replace them, leading to loss of bone thickness (bone mass or density). Bones then become thinner; even a minor bump can cause a fracture (break or crack). Any bone can be affected by osteoporosis, but the most common sites are in the hip, spine, wrist, ribs, pelvis and upper arm. Often, there are no signs or symptoms of osteoporosis until a fracture occurs.
Risk factors for osteoporosis
Any history of osteoporosis and fractures.
Conditions and medications including:
- cortico-steroids (commonly used for asthma)
- rheumatoid arthritis
- over-active thyroid or parathyroid glands
- coeliac disease; other chronic gut conditions
- chronic liver or kidney disease
- women whose periods have stopped for 6-12 consecutive months (excluding pregnancy, menopause or hysterectomy) or who have experienced early menopause
- excessive alcohol consumption
- nutrition lacking in calcium
- lack of sunlight exposure (may cause vitamin D deficiency)
- lack of physical activity over many years
- low body weight
What is a DXA scan?
A DXA (Dual-emission X-ray Absorptiometry) scan measures bone mineral density. It's the 'gold standard' tool for diagnosing and following osteoporosis. X-ray beams with different energy levels are aimed at the bones and the bone mineral density determined from the absorption of each beam by bone. The scan costs $80-$300 and Medicare reimburses people aged over 70 and/or at high risk of osteoporosis.
Calcium and bone health
Calcium comes from diet and is vital for building and maintaining bone. Combined with other minerals, it forms hard crystals, giving bone its strength. Almost all our body's calcium is in our bones. If calcium intake through nutrition is poor, some of the calcium crystals in bone dissolve, giving their calcium back to the bloodstream. This can result in loss of bone strength. Weight bearing exercise, where bones and muscles work against gravity, is the key to good bone health. "High intensity, rapid impact exercise stimulates bone cell formation," explains Shelley.
Hormones and bone health
Women are at greater risk of developing osteoporosis than men. "When oestrogen levels decrease rapidly after menopause, bones lose calcium and other minerals at a faster rate," explains medical director of Osteoporosis Australia, and head of medicine at Western Hospital, Professor Peter Ebeling. "Bone loss occurs at a rate of about 1-5% per year after menopause. Hormone Replacement Therapy (HRT) may be used to slow this process."
Smoking, alcohol and caffeine
"Any degree of smoking harms bone," says Peter. "Recent research indicates that moderate alcohol intake (no more than two standard drinks per day) may actually improve your bone health. Importantly, excessive alcohol intake is associated with higher incidence of fractures in women." Drinking more than three caffeinated beverages per day may reduce calcium absorption. Excessive caffeine is also associated with reduced dietary calcium intake.
Physical activity and bone health
Weight bearing exercise, where bones and muscles work against gravity, is the key to good bone health. "High intensity, rapid impact exercise stimulates bone cell formation," explains Shelley. "Other exercises like yoga may also be beneficial, as improved balance is associated with reduced risk of falls." Exercise recommendations are different for bone and cardiac health. Fifteen minutes of weight bearing exercise, four times per week; for example gym resistance training, medium impact aerobics, skipping, dancing or jumping exercises, all contribute to optimal bone health.
Tips for keeping bones healthy
Under 40 years
- Fifteen minutes, four times a week of weight bearing exercise.
- Ensure adequate calcium intake of 1000mg/day (equal to three serves of dairy foods).
- Ensure an adequate vitamin D level through regular sunlight exposure.
- Eat a moderate, healthy diet high in fruit and vegetables.
- Avoid excessive intake of alcohol and caffeinated drinks.
- Organise a DXA scan, as 15% of bone is lost at menopause. The results can prompt you to take simple steps to reduce the progression of osteoporosis or even reverse the effects.
- Assess your osteoporosis risk factors using a simple online tool like the World Health Organisation fracture risk assessment: (http://www.shef.ac.uk/FRAX/tool.jsp?country=31) or the Garvan Institute's fracture risk calculator (http://garvan.org.au/promotions/bone-fracture-risk/calculator/).
- Ask your GP whether you need to pay attention to other medical risk factors.
- Fifteen minutes, four times a week of weight bearing exercise.
- Ensure adequate calcium intake (1000mg/day if you are under 50 years, 1300mg/day if over 50).
- Ensure adequate vitamin D level through regular sunlight exposure.
- Refer to tips for 40-55 years (previous page).
- See your GP if you have had a minimal trauma fracture (a break caused by only a minor bump/fall).
- If you have had height loss of 3.5cm or more (compare your height now to your height in your thirties), request a spinal x-ray to rule out spinal fractures.
A word on calcium supplements
Calcium needs are generally best met through diet. Two serves of dairy and another serve of calcium-rich foods like broccoli, beans, almonds, tinned salmon and sardines equates to about 1000mg calcium. In order to meet 1300mg per day of calcium, supplements may be prescribed by your GP. Peter recommends taking these at night, as this is when bone 'turnover' increases. It's important not to overdose on calcium supplements, as very high calcium intake (2400mg/day) has been linked with heart disease.
The importance of vitamin D
Vitamin D is essential for bone health. It helps increase the absorption of calcium from the stomach, regulates the amount of calcium in the blood and strengthens the skeleton. The main source of vitamin D is exposure to sunlight, with small amounts also available in some foods.
Who's most at risk of vitamin D deficiency?
- Older and/or institutionalised people – particularly those who stay indoors or cannot walk (so have limited sunlight exposure).
- People with gastrointestinal disease.
- People taking certain medications (e.g. anti-epileptics).
- People who cover their skin for religious/cultural reasons.
- Dark-skinned people.
- Pregnant women.
- Postmenopausal women.
How much sun is enough?
Exposing face, arms, hands or legs to the sun for 10 minutes in summer, 15-20 minutes in spring and autumn, and 30 minutes in winter outside peak UV times (10am-2pm or 11am-3pm daylight saving times) should give you enough vitamin D. People with darker skin may need longer sun exposure periods. During these short times, there is usually no need to worry about sun protection such as sunscreen, as sunscreen blocks the UV from touching the skin and therefore no vitamin D is created.
Always protect yourself when the UV index is above 3, which indicates sun strong enough to damage skin. For example, cover your body with clothes and apply sunscreen to exposed areas. To check daily updates on the UV index visit: www.sunsmart.com.au. Don't use solariums as a substitute for sunlight. The UV radiation in solariums doesn't help to produce vitamin D and will not help with vitamin D deficiency; it increases your risk of skin cancer by exposing your skin to dangerous levels of UV radiation.
For more information
Fact sheets on bone health and vitamin D are available at www.jeanhailes.org.au
Content updated June 2011