Thursday, August 11, 2011

Osteoporosis: The Role of Calcium in Maintaining Bone Strength

This is a more concise version an article that I have written some time back on the importance of calcium intake...

What is Calcium?

Calcium is the main constituent of bones. Calcium is also important for muscle and nerve health. Our bones and teeth contain 99% of the body's total calcium and the remaining calcium is found in our bodily fluids. 
Our sole source of calcium is from our diets.

Importance of Calcium during the Younger Years

During childhood and adolescence, more bone tissue is deposited than it is broken down leading to bone growth and increased density. More than 90% of a person’s bone mass develops before  20 years of age, and half of that bone mass develops from age 11-15 years. Thus, calcium intake is critical for this age group.

Our bones amass calcium to reach their peak mass at around age 30, after which, new bone formation starts to slow. As one gets older, getting enough calcium everyday is equally important to slow down the loss of calcium from bones.

Higher calcium intake may also be needed during pregnancy in order to build strong bones for the baby. Higher calcium intake is also recommended for post-menopausal women to reduce the risk of osteoporosis.

What is Osteporosis?

Osteoporosis, which means “porous” bones, is a silent disease where bone density decreases leading to bone fragility and increased risk for fracture. There are usually no signs and symptoms in the early stages but in the later stages, those who are affected may develop back pain, stooped posture usually associated with a humped upper back and/or bone fractures commonly in the hip, spine, wrist and upper arm.

Osteoporosis can be broadly classified into primary and secondary osteoporosis. Primary osteoporosis is age-related, typically occurs in postmenopausal women and elderly above age 70. Secondary osteoporosis can occur in people of any age. Possible causes are prolonged usage of certain medicines such as oral corticosteroids or other health conditions such as kidney disease or hormonal disorders.

Bone mass density test is often used in the screening of osteoporosis.

Risk factors for osteoporosis

- having a family history of osteoporosis
- over the age of 65
- extended immobilization
- being underweight (BMI <19kg/m2)
- having insufficient dietary intake of calcium, phosphate and vitamin D
- cigarette smoking
- excessive caffeine or alcohol use
- menopause.

Can Osteoporosis be prevented? 
Prevention and treatment measures for osteoporosis involve ensuring an adequate intake of calcium and vitamin D, regular exercises to maximize bone and muscle strength and to reduce the risk of falls, avoidance of smoking and excessive alcohol consumption and undergo calcium supplementation or medication with bisphosphonates to preserve bone mass or stimulate new bone formation, on your doctor’s advice.

Physical activity during childhood and adolescence increases bone density and strength. This means that children who exercise regularly are more likely to reach a higher peak bone mass by age 30 and are less likely to develop osteoporosis in future. Exercises that can prevent osteoporosis are weight-bearing exercise that works against gravity and resistance exercise. Weight-bearing exercises include walking, jogging, stairs-climbing, playing tennis, rope-jumping and dancing. It is recommended for weight bearing exercises to be done for a total of 30  minutes on most days of the week. Resistance exercises include activities that use muscle strength to build muscle mass and strengthen bones. These activities include weight lifting and using elastic exercise bands. They are recommended to be done 2-3 times per week. Exercise also has the additional benefits of increasing muscle strength, coordination, and balance thus decreasing the risk of falls.

However, elderly, people diagnosed with osteoporosis, people with heart or lung disease, and people who have not exercised for most of adulthood should check with their physicians before beginning any exercise program.

What Foods Contain Calcium? How can I obtain more Calcium from my Diet?

Eating a well-balanced diet would provide the body with nutrients and enough calcium for strong bones. Foods that are rich in calcium include calcium-fortified products (such as high-calcium milk powder), low-fat yoghurt, low-fat milk, ikan bilis (with bones intact), almonds, dried figs, soya beans, beancurd, cheese and green leafy vegetables such as kailan and spinach.

You can obtain more calcium from your diet by adding skimmed milk powder or low-fat milk to your soups, smoothies, milkshakes and sauces. Eating more low-fat dairy products and choosing breads, cereals and drinks that are calcium-fortified are also ways to contribute to a higher calcium intake.

7. What if I'm lactose intolerant?

Lactose intolerant is the inability for one to digest lactose, a sugar found in milk and dairy products. In the case of mild lactose-intolerant, try adding small quantity of milk to soups and cereals, taking yoghurt or low-fat cheeses that are low in lactose such as cheddar, Swiss or parmesan.

You can also go for other calcium sources such as lactose-free milk and dairy products, or other calcium-rich food such as soya bean milk, green leafy vegetables, tofu, almonds, ikan bilis and sardines with bones.

Lactase, the lactose-digesting enzyme which is available commercially, can be added into milk or other dairy products to break down the lactose before consumption. It can also be taken whenever you eat or drink any offending dairy product to prevent cramps, bloating and diarrhea.

For more information on the recommended daily calcium intake according to age, refer to HPB site here or the table below.

Recommended elemental calcium requirements based on age
Calcium intake (mg)
Vitamin D (IU)
0-6 months
6-12 months
1-3 years
4-8 years
9-18 years
19-50 years
Older than 50 years
1200 (women)
1000 (men)
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