Bone is a living substance and, like tissues such as the skin, it is constantly being removed and replaced. Normally this process is in balance, with the amount of old bone removed being replaced by an equal amount of freshly formed bone. To keep this balance it seems that bones need mechanical stress (the harder they have to work against the force of gravity, the stronger they get), together with a dietary supply of calcium, phosphorous, and tiny amounts of various other nutrients.
The types of exercise that seem most beneficial for bone strength are the weightbearing ones, such as walking, dancing, jogging, lawn bowls, gardening, golf and tennis. Associated benefits are an increase in flexibility and an opportunity for mixing with other people. How you feel during exercise is an important guide. Try to maintain a feeling of being a little ‘pushed’ without moving to the breathless stage.
Australian health authorities say that women at and after menopause need an estimated iooo to 1500 mg of calcium a day to be in calcium balance. The Melbourne Women’s Midlife Health Study indicates that only 5 per cent of women aged between forty-five and fifty-five have sufficient calcium in their diet to meet this recommendation. The study found that about 20 per cent of women get about 250 mg of calcium a day, a quarter of the recommended daily intake, and another 35 per cent have a calcium intake of less than 500 mg.
Eating foods rich in calcium or taking calcium supplements each day can bring calcium intake up to recommended levels. Foods rich in calcium include milk, tofu, cheese, soy milk, yoghurt, green vegetables, parsley, cabbage, seaweed, almonds, hazelnuts and oily deep sea fish. Calcium-rich herbs include alfalfa, camomile, oatstraw and skullcap. For women who have cut back on dairy foods because of concerns about weight gain, low-fat alternatives are the ideal substitute. Some women have a deficiency of the lactase enzyme, which means that their bodies are incapable of metabolising dairy products. If you are one of these people you will need to get your calcium from other sources, such as yoghurt, which itself contains the lactase enzyme.