Do you take little or no exercise?
Do you smoke?
Do you drink a lot of alcohol?
Does your diet contain little or no calcium?
Do you have a fair skin and fine bone structure?
Do you have a family history of broken bones?
Are you a postmenopausal woman?
Are you taking excessive thyroid medication or high doses of cortisone-type drugs for conditions such as asthma, arthritis, or cancer?
The more times you answer “yes”, the greater your risk of developing a bone-thinning disease that causes debilitating fractures of the spine, hip and wrist. This disorder is called ‘osteoporosis’ and affects millions of people worldwide. In the UK alone there are an estimated 3 million people with osteoporosis. It mainly affects people in middle and later life and is around six times more common in women than it is in men.
Osteoporosis is a condition in which bones are thinner than they should be – and thin bones are more likely to break. Gradual loss of calcium from bones is a normal process in middle and later life but if the loss is rapid or severe (as may happen to women at menopause) then the bones become brittle. They can break easily and are hard to heal. A fracture in a bone weakened by osteoporosis may require weeks, sometimes months, of hospitalisation. Some breaks never really heal properly and impair the physical ability of those affected, preventing them from leading a normal active life.
Our bony skeleton is basically a protein mix in which crystals of calcium and phosphates are embedded.
The majority of our bones consist of two parts: an outer shell-like layer of hard, compact bone (termed ‘cortical’ bone) and an inner region of sponge-like cancellous bone (termed ‘trabecular’ bone).
Cortical bone is very dense and provides a strong tubular structure with an outer fibrous covering called the ‘periosteum’, to which ligaments, tendons and muscles are attached. Cortical bone accounts for around 80% of our total skeletal mass.
Trabecular bone is found mainly in the ends of the long bones of our arms and legs – which resemble the structure of an ‘Aero’ chocolate bar (see Diagram). This is a strong bony matrix, that gives lightness to our bones. Trabecular bone accounts for around 20% of our total bone mass.
The central shaft of long bones are basically hollow and contain the highly nutritious bone marrow, where, for example, most of our red blood cells are produced.
People with ‘heavy frames’ normally have higher levels of cortical bone than people with ‘light frames’. The skeleton of males is on average around 30% heavier than females and about 10% higher in blacks than in whites.
From birth until death bone tissue is constantly being formed, broken down and re-formed in a process called ‘re-modelling’. The cells that build bones are called osteoblasts and those that break down bone and help create the bone shape are called osteoclasts.
During puberty, rapid bone growth occurs – our bones get longer, thicker and more dense. Our peak bone density occurs between the ages of 20 and 30. Once this has been achieved, the osteoclast and osteoblast activity remains in balance until around 45-50 years of age. After this, the osteoclast activity becomes greater than the osteoblasts and the person slowly begins to lose bone mass. A variety of genetic and lifestyle factors will slow or accelerate this process. For example, a woman going through the menopause will have accelerated loss of bone. The early occurrence of menopause by natural or surgical means also increases the risk of accelerated bone loss. This is because the protective effect of the female hormone oestrogen is lost since its natural production ceases after the menopause. Oestrogens act directly on bones, increasing their density. Studies have demonstrated that oestrogen replacement therapy can prevent the subsequent loss of bone by as much as 50%, whilst also helping alleviate menopausal symptoms. (Oestrogen may also reduce the risk of heart disease by as much as 50%; however there are some concerns that long-term use of oestrogen may increase the risk of breast cancer). Other menstrual problems, such as those caused by bulimia & anorexia, or excessive exercise, may also lead to loss of bone mass.
Prevention – the good news is that in the majority of cases osteoporosis is preventable – regular exercise and a healthy diet can make a great deal of difference to the health of our bones.
Regular Exercise promotes healthy bones – and helps prevent osteoporosis
It is well known that bone loss is much greater in those leading sedentary, inactive lifestyles. One study showed that when healthy individuals underwent complete bed rest for 10 weeks, they lost 10% of their bone mass!
Exercise, particularly weight-bearing and resistance exercise, which places a healthy stress on the bones is vital for maintenance of our total bone mass.
Weight-bearing activities such as walking, running and racket sports seem more effective than non-weight-bearing activities, such as cycling and swimming. Resistance exercises, such as lifting, carrying, pulling and pushing, or a gym programme designed to increase overall strength and muscle tone, will also have a highly beneficial effect on your bones, making them stronger and sturdier.
Encouraging children to play a variety of games and sports and lead active lifestyles, helps them to increase their peak bone mass, thus creating stronger and healthier bones. This stands them in good stead and helps reduce the risk of osteoporosis as they become older.
Regular exercise in later life is vital for healthy bones. As people age, they tend to become less physically active, which leads to a reduction in bone density and to the increased risk of fractures.
So, for good bone health make sure that:
- your diet contains adequate amounts of calcium from foods such as low-fat dairy foods, leafy vegetables, nuts and seeds
- don’t smoke
- drink alcohol only in moderation
- don’t become bone idle – take regular exercise!