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Life can be hectic in your 20, 30s and 40s due to friends, family and work commitments. If you did not think much about the state of your bones before, now is a good time to start.

Bone production

Bone is living tissue made up of specialised bone cells and, like the rest of the body, it is constantly being broken down and renewed. Bone growth is nearly complete by the end of puberty, with only a small increase in bone strength occurring after the late teenage years. From the mid-30s on there is a mismatch between bone production and bone breakdown: Bone loss starts to overtake bone gain. It is part of the normal ageing process that bones lose their calcium (mineral) and protein (collagen) content. Although your bone mass may have reached its peak, it is important to continue to limit the degree of age-related bone loss. This will reduce your risk of osteoporosis in later life. Osteoporosis is a condition in which loss of bone strength makes bones more fragile and likely to break.

Maintaining healthy bones

Gaining bone strength

Like muscles, bones need physical activity to gain strength. The types of physical activities most beneficial to bones include weight-bearing and strength training exercises. The term ‘weight-bearing’ refers to exercises performed on your feet, working against the force of your own body weight. Examples include walking, running, jumping, tennis and dancing. ‘Strength training’ includes weight lifting and other resistive exercises.

Healthy eating

The years from age 20 to 40 represent both your reproductive and premenopausal years, thus it is vital that you have an adequate calcium intake. The major source of calcium comes from dairy foods. Women should aim to have 2-3 serves of dairy foods per day in order to meet their daily calcium requirement.

Vitamin D is also an important requirement for maintaining healthy bones, as it assists in depositing calcium in bone. The major source of vitamin D is manufacture in the skin upon exposure to sunlight. Only 10-15 minutes of sunlight are needed each day to provide adequate levels of vitamin D.

Hormones

Hormones such as oestrogen are important in the development and maintenance of bone health. If you have regular menstrual periods you will have sufficient levels of oestrogen to provide adequate bone protection.

Avoid smoking

To protect bones it is advisable not to smoke. Women who smoke lose bone strength faster than women who do not smoke.

Special considerations

In women, osteoporosis is more commonly seen after the menopause. However, some young women may develop osteoporosis at an earlier stage of life due to various illnesses or hormonal deficiencies. During their 20s-40s, many women start to think about issues relating to their bone health. Often this is spurred on by women finding that their mothers have developed osteoporosis. Women who have a family history of osteoporosis are at higher risk of developing the condition in the future.

Eating disorders

Women who develop eating disorders in early adolescence, when the skeleton is in the process of growing, severely reduce their potential to achieve a high peak bone mass. This can lead to the development of osteoporosis at a younger age, especially if the eating disorder persists for several years. It is not uncommon for women who have had an eating disorder since their teenage years to develop osteoporosis by their early 20s. Even women who develop an eating disorder after the process of skeletal growth has been completed will be at increased risk.

Athletes

Adolescent females and young women who participate in excessive amounts of exercise may place themselves at increased risk of bone loss. This is more likely to occur if such activity results in amenorrhoea (menstruation stops) or disordered eating habits.

Pregnant and breastfeeding women

Calcium requirements are increased during pregnancy, as the foetus draws calcium from the mother in order to build the foetal skeleton. This demand is largely met by an increase in calcium absorption through the gut. Women who breastfeed also need to increase the availability of calcium in their circulation. This is achieved largely by calcium being extracted from the skeleton.Normal pregnancy and breastfeeding are associated with a certain amount of bone mineral loss, which generally recovers within a year if the woman is not pregnant again or breastfeeding. The mechanism behind this recovery is still not fully understood.

Approaching midlife

Women generally start to lose bone mass in the years leading up to menopause, since oestrogen levels are already starting to drop even though menstrual periods may still be occurring. Your gastrointestinal system becomes less efficient at absorbing calcium from food, and it is believed that this process is also due to the loss of oestrogen. The kidney also becomes less efficient in conserving calcium, setting up a state of potential calcium loss in the blood. Your body compensates for this by drawing calcium out of the bones.

Early menopause

Menopause occurring before the age of 45 is regarded as early menopause. Women who undergo early menopause may start to lose bone at a significantly earlier age (putting them at a greater risk of developing osteoporosis at an earlier age) than women who undergo menopause in their 50s.

Further resources

Content updated 3 August 2011