GET OUTSIDE

Along with calcium, vitamin D is crucial for bone development. Sunlight is by far the best source. Exposing your face and arms for 30 minutes a day between April and October - when the sun's rays are at their strongest - is enough to ensure levels remain stable, says Professor Graham Bentham, an environmental scientist at the University of East Anglia. "Ideally, people should be getting 10-minute stints in the midday and mid-afternoon sun during those months when the UVB radiation that creates vitamin D is strongest," he says. That isn't an excuse to roast in the sun, though.

START SKIPPING

Weight-bearing exercise is essential for building bones. And, according to the National Osteoporosis Society, research shows that just 15 skips a day can make a significant difference. Meanwhile, Dr Joan Bassey, a physiologist at the University of Nottingham Medical School, has found that taking stairs instead of a lift also helps: running upstairs provides on average 20 beneficial, high-impact jolts to the spine and hips; repeated five times a day, and the 100 jolts will protect your skeleton. "Bone is a living tissue that reacts to increases in loads and forces by growing stronger," Bassey says. "The effect is achieved by increasing the number of muscle fibres that pull and tug on bones, causing them to become denser and stronger."

DON'T UNDEREAT OR OVEREXERCISE

Dancers, gymnasts, long-distance runners and people with anorexia or bulimia nervosa are all known to be at greater risk of osteoporosis than the general population. Why? Because their low body fat levels and often inadequate nutrient intake leaves them vulnerable to weak bones. The same goes for yo-yo dieters and excessive exercisers. In women, amenorrhea (the cessation of periods) is a warning sign that levels of the hormone oestrogen have plummeted to those of a postmenopausal woman. Since oestrogen is vital for the development of bone, it can mean a woman may start losing bone mass, putting her at risk of osteoporosis.

MODERATE YOUR CAFFEINE

Some researchers have linked a high caffeine consumption (more than six cups of coffee a day) with the leeching of calcium from bones. One recent American study at the Creighton University Osteoporosis Research Centre in Nebraska, published in the American Journal Of Clinical Nutrition, showed that people who drank cola and other caffeinated carbonated drinks tended to excrete calcium through their urine. However, when researchers at the University of Cambridge looked at the diets of 1,200 elderly British women, they found that the tea drinkers had stronger bones than the non-tea drinkers. Reporting in the American Journal Of Clinical Nutrition a couple of years ago, they suggested it was the flavonoids (plant chemicals that act as antioxidants) in tea that were probably responsible for promoting bone density. Tea also contains fluoride, an important mineral for bone development. Dr Verona Hegarty, a gerontologist who led the study, said the number of cups of tea a day did not seem to play a role, but that women who added milk to their tea had much higher bone mineral density in the hip area.

AVOID FIZZY DRINKS

Drinking large amounts of fizzy drinks may weaken your bones, according to researchers at Denmark's Centre for Advanced Food Studies reporting in the journal Osteoporosis last year. Manufacturers make drinks fizzy by adding carbon dioxide, which also increases acidity. As this acid enters the bloodstream, the body attempts to neutralise it with calcium, the alkaline bone-building mineral. An earlier study of 400 schoolgirls at Harvard Medical School produced similar findings. Dr Grace Wyshak found that one-fifth of the fizzy drink addicts she questioned had suffered fractures by the time they were 20. Wyshak suggested the phosphorous content of the drinks alters the delicate balance of minerals in the body and causes calcium to be broken down.

START ROWING

Although it is not strictly weight-bearing exercise, studies have shown that the resistance of rowing against water (an indoor machine has the same effect) significantly improves bone density in the spine. Other sports to try include running (hips) and weight training (wrists, hip and spine), which build bone density by up to 2% in 18 months.

FOLLOW A BONE-BUILDING DIET

Milk and dairy foods are the obvious sources of calcium (research at the University of Sheffield medical school showed that drinking a pint of skimmed milk every day led to a 3% increase in bone mineral density over 12 months) but by no means the only way to build bones. Try eating more oily fish and eggs (rich sources of vitamin D), dark green, leafy vegetables and tinned fish (such as salmon). Foods to limit include those containing oxalic acid (almonds, rhubarb and chocolate) and phytic acid (wheat bran, brown rice and nuts), both of which inhibit calcium absorption. Excessive intakes of salt and alcohol are bad news, as is smoking. A supplement of vitamin D and calcium can be beneficial if you struggle to get enough from food.