The osteoporosis-free diet

Most people don’t know that bone is living tissue. Throughout our lives, like our hair and skin, old bone is continuously being broken down and replaced by new bone – a process called remodelling. Osteoporosis occurs when bone breaks down at a faster rate than it can be replaced, ultimately causing bones to become brittle and, sometimes, break.

In their new book, Strong Women, Strong Bones Dr Miriam E. Nelson & Dr Sarah Wernick (£12.99, Piatkus, 2000) outline the process of bone development and the anatomy of osteoporosis in an accessible and straightforward way. They also help to dispel many of the myths about the disease, and provide answers to frequently asked questions about nutrition and exercise.

As Drs Nelson & Wernick explain, the most important nutrients needed for the process of renewal to take place in bones are calcium, phosphorous, protein, vitamin D, magnesium and zinc. This is because they help make bones harder through the chemical process of calcification. The majority of bones are formed during childhood and adolescence and although bones generally don’t increase in length after adolescence, they do continue to increase in density so that 90-95% of our bone mass is reached by the age of 20.

By the time we reach 30, bone begins to break down faster than it can be replaced, a rate which increases each year. During menopause, women can lose as much as 50% of their bone mass because levels of oestrogen, a female hormone that has a protective effect on bone, decrease severely. Many women go on hormone replacement therapy (HRT) to slow down bone loss. But oestrogen levels do not naturally go back to their previous levels. Consequently, as bone density decreases, the bones gradually lose their strength and become more brittle. If the losses are large, bones can become so weak that they break.

Calcium plays the most important role in the development and maintenance of a healthy skeleton. 99% of our calcium intake goes direct to our bones, providing them with the strength and rigidity to enable us to stand upright, walk, jump and run.

At present, there is no internationally agreed recommendation for daily calcium intake. The Department of Health’s 1999 report, ‘Nutrition and Bone Health’, daily recommendations are:

• Age 19-50: 700mg per day
• Age 11-18 (girls): 800mg
• Age 11-18 (boys): 1000mg
• Age 7-11: 550mg

The National Osteoporosis Society, suggest:

• General: 1000mg per day
• Age 7-12: 800mg per day