Osteoporosis affects one in three women in the UK. Dr Wynnie Chan reviews Strong Women, Strong Bones and explains how to safeguard against brittle bones through healthy eating and exercise.

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

Although these figures differ, we clearly need a regular intake of calcium throughout our lives, particularly during childhood, adolescence and early adulthood. This is because the greater the bone mass we accumulate during this period, the better prepared the skeleton will be for later bone loss, thereby reducing the risk of fractures.

The best sources of calcium come from milk and dairy products, canned fish (such as sardines and salmon), tofu, prawns and green leafy vegetables. White bread, some fruits (such as oranges and dried apricots) eggs and peanuts provide only small amounts of calcium.

However, in order for the body to absorb calcium from these foods, it is also important to get a regular dose of Vitamin D, the easiest source of which is exposing your skin to natural sunlight. This vitamin helps the body take in calcium by ‘unlocking the door’ to the intestines, and allowing calcium to enter the bloodstream. Approximately ten to fifteen minutes of sun exposure to your hands and face, two to three times a week is sufficient.

Consumption of the following items can affect the development and progression of bone renewal:

• high fibre intake, particularly raw bran, which reduces the availability of calcium for the body, as fibre binds with calcium and is then eliminated from your body.
• high alcohol intake (anything above the recommended level of 2-3 units a day, with 1 unit being equivalent to one small glass of wine, or ½ pint of beer), which accelerates bone loss by interfering with the body’s ability to absorb calcium
• high caffeine intake (around 15 cups a day) which may affect the balance of calcium in the body by interfering with the body’s ability to absorb calcium
• smoking and low body weight, which tend to induce an earlier menopause, which in turn advances the development of osteoporosis

As far as exercise, physical activity is thought to benefit the skeleton by helping to improve bone density and bone strength, as well as helping balance. Like muscles, bones grow stronger through use and exercise. The authors suggest different bone-boosting workouts and exercise regimes for up to a period of 12 weeks. These include jogging, jumping, and weight training, while for women after menopause, suggested activities include intermittent jogging, stair climbing, and light weight training.

It’s never too late to start changing your diet to protect yourself from developing osteoporosis. Based on the latest scientific evidence, doctors Nelson and Wernick provide different menu plans to help meet calcium dietary requirements, which also address the needs of vegans, people who are lactose intolerant and people who don’t like milk or dairy products. The following is a sample diet plan to help meet your daily requirement of calcium by providing at least 1000mg calcium. (Choose one from each heading.)

Breakfast

• 200ml semi-skimmed milk with muesli and dried apricots, 1 piece white bread, toasted, reduced fat spread and marmite.
• 140g pot reduced fat yoghurt with bowl mixed fruit salad, 1 pancake with maple syrup.
• 200ml soymilk fortified with calcium with Weetabix, dried prunes, 1 piece pumpernickel bread with reduced fat spread.
• 1 bowl porridge made with skimmed milk and topped with strawberries, 2 rye crispbreads with cottage cheese.
• 1 bagel with reduced fat cream cheese and pineapple, half a grapefruit.
• Coffee or tea with reduced fat milk, 1 glass of Tropicana calcium-fortified orange juice

Lunch

• Cheese and mushroom omelette with mixed green salad and tofu dressing, 1 white roll, 1 orange.
• Potato wedges with sour cream and chives, 1 bowl mixed fruit salad with reduced fat fromage frais.
• Pita bread stuffed with canned salmon, cucumber and reduced fat mayonnaise, 1 portion of melon.
• Ploughman’s sandwich made with French stick, cheddar cheese, pickle, and 1 bowl of mixed green salad with reduced fat ranch dressing.
• 1 bowl of creamy leek and potato soup, with walnut bread, tomato and mozzarella salad with reduced fat French dressing.
• 1 glass of water, either tap or bottled.

Dinner

• Spinach lasagne made with skimmed milk and ricotta cheese, mixed green salad served with yogurt dressing, 1 serving of ice cream.
• Prawn and mixed vegetables stir-fry served with noodles and topped with chopped peanuts, 1 serving of reduced fat cheesecake.
• Tofu salad (made with carrots, beansprouts, spring onion, green peppers and courgettes in a vinaigrette dressing), served with steamed millet, 1 serving frozen fruit yogurt,1 serving of rhubarb crumble with custard.
• Tempeh burgers served with mixed bean salad in a creamy Italian dressing and baked sweet potato, 1serving of rice pudding made with skimmed milk.
• Mixed vegetables enchiladas made with olives, green and red pepper, onions, green beans, broccoli, canned tomatoes and cream cheese, served with refried beans and tortilla chips, 1 serving of mixed fruit salad.
• 1 glass of water either tap or bottled.

Extra boosts:

• Banana smoothie made with yoghurt, banana and lots of ice.
• Strawberry milkshakes made with skimmed milk.
• Handful of almonds.
• Handful of raisins or prunes.