Diet and lifestyle changes key to protecting women against osteoporosis
Asian women can fight back against osteoporosis with diet and lifestyle changes, writes Jeanette Wang
Women may live longer than men but they may not necessarily be healthier. The International Osteoporosis Foundation (IOF) said during yesterday's World Osteoporosis Day the quality of life for women would be seriously jeopardised without action to protect their bone health.
Osteoporosis can strike anyone but post-menopausal women are most vulnerable. Worldwide, the IOF estimates that 200 million women are affected by osteoporosis and about one in three women older than 50 will suffer a fractured bone due to it.
The problem is more pronounced in Asia, not only because populations in the region are ageing rapidly, but also because of physical and lifestyle factors. Asian women tend to have lower bone mass and density, and smaller body frames than the worldwide averages.
A traditional Chinese diet also tends to be low in calcium, the key mineral for healthy bones. Average calcium intake in Chinese diets hovered around 400mg in the 1980s and 1990s, and was between about 500mg and 600mg in the 2000s, according to a report by the Osteoporosis Society of Hong Kong, Guidelines for Clinical Management of Postmenopausal Osteoporosis in Hong Kong, published in April. Average calcium intake is further reduced because lactose intolerance, an inability to digest a sugar found in milk and its products, is more common among Asians than Europeans, for example.
By 2050, the IOF estimates that half of the world's osteoporotic fractures will occur in Asia. In the mainland, almost 70 million people over the age of 50 suffer from osteoporosis and the disease causes about 687,000 hip fractures a year.
From 2002 to 2006, hip fractures among those over 50 year in Beijing increased by 58 per cent in women and 49 per cent in men, according to a study by the Chinese Academy of Medical Sciences published last year in the Journal of Bone and Mineral Research.
Urbanisation and lifestyle changes are suggested as the main reasons for such a rapid change. Previous studies in a number of Asian countries have shown the incidence of hip fractures is directly proportional to economic development.
The burden is not only physical but financial. In 2006, US$1.6 billion was spent on hip fracture care in China, the IOF says, and this is projected to rise to US$12.5 billion by 2020 and US$265 billion by 2050.
Women are a key concern for the IOF. "Around the world it is women over 50 who most often take on the burden of care for elderly parents and disabled or sick family members," says the IOF in their report Bone Care for the Postmenopausal Woman.
Report co-author Professor Bess Dawson-Hughes, the director of the Bone Metabolism Laboratory at the Human Nutrition Research Centre on Ageing at Tufts University in Boston, says: "Although the earlier prevention begins the better, when a woman reaches menopause she must not delay any longer. Menopause is the critical time to take preventive measures against bone loss and muscle weakness that can lead to osteoporosis, falls and fractures."
Oestrogen plays a vital role in regulating the turnover of bone. It is a daily cycle of bone formation and bone resorption, the breaking down of bones. The process ensures that the skeleton maintains its structural integrity.
In young people, the body forms enough new bone to replace what is lost. After age 30, bone mass begins to decline and for women, the process speeds up again after menopause. As oestrogen levels decline, the equilibrium in producing and consuming bones is lost. Osteoporosis develops when the body cannot replace bone fast enough.
The disease has no symptoms until a fracture occurs. It can affect any bone in the body but most commonly affects the spine, wrists and hips. Apart from pain and disability, hip and spine fractures are also associated with a higher risk of death - 20 per cent of people who fracture a hip die within six months.
"An individual who has experienced a fracture is at double the risk of suffering a second fracture as compared to a person without fractures. In postmenopausal women, a broken wrist or a spinal fracture is often the harbinger of more fractures to come and should be taken as a warning that testing and preventive treatment is needed," says Professor Cyrus Cooper, chairman of the IOF's committee of scientific advisers.
While there are some risk factors that cannot be mitigated - such as family history, age at menopause and diseases such as rheumatoid arthritis - lifestyle and diet changes can lower the risk of osteoporosis and fractures.
Here are the suggestions from the IOF report.
Sedentary people are more likely to suffer hip fractures. Women who sit for more than nine hours a day are 43 per cent more likely to have a hip fracture than those who sit for fewer than six hours as day, according to a study in the Journal of Bone and Mineral Research.
Exercise has been shown to boost bone mineral density by 1-2 per cent in randomised, controlled trials, but its main benefit appears to lie in increasing muscle mass and the resulting improvement in balance and strength - both important factors in preventing falls and fractures.
Pick an exercise that suits your needs and abilities but the IOF recommends that most people should exercise for 30 to 40 minutes, three to four times a week. Exercises should be both weight-bearing, such as dancing, hiking, jogging and rope skipping, and muscle-strengthening, including using elastic resistance bands and weights.
Tai chi is recommended by the Osteoporosis Society of Hong Kong as an "appropriate and safe exercise for older adults for general health and fall prevention".
A review of 47 studies showed the benefits of the Chinese martial art were reported in balance and strength, cardiovascular and respiratory function, flexibility, a healthier immune system, relief from the symptoms of arthritis, improved muscular strength and mental well-being.
Get the right nutrients Calcium: Postmenopausal women should get 1,300mg of calcium a day, according to the World Health Organisation. One hundred grams of steamed tofu (510mg of calcium), four figs (506mg of calcium) and a 150-gram pot of plain low-fat yogurt (243mg of calcium) will meet that daily need.
In the past few years there has been substantial debate about the efficacy and safety of calcium supplements, but there's no question that diet should be the primary source of the mineral.
Vitamin D: This vitamin aids bone health in two ways. It helps calcium absorption and with important bone development and maintenance. It also has a direct effect on muscle performance and reduces the risk of falling.
The US National Institutes of Health recommends a daily intake of 600 IU (15 micrograms) for adults aged up to 70, and 800 IU (20 micrograms) for older people. A 90-gram serving of cooked salmon provides about 450 IU of vitamin D.
Protein: Getting enough protein should not be a problem for anyone eating a meat-heavy modern diet, but vegetarians and vegans might want to take extra care. The Framingham Osteoporosis Study from the US found that lower protein intake and lower animal protein intake were associated with loss of bone mineral density in the hips and spines of older people.
And you know the rest … Don't smoke: Smoking is linked to several risk factors for osteoporosis, including early menopause and excessive thinness. Both current and ex-smokers face an increased risk of any fracture compared to non-smokers.
Drink in moderation: Up to two glasses, 120ml each, of wine a day does not negatively impact on bone health. In fact, a Finnish study reported that mild to moderate alcohol intake was actually associated with greater bone mass among postmenopausal women.
Maintain a healthy weight: Being lean is good - up to a point. Excessive thinness, plus the risk of malnutrition and loss of oestrogen, can be devastating to bone health.