HOW COMFORTING it is for parents of the child who won’t eat to know that at least she’s getting calcium from that evening cup of milk. Drinking milk and eating dairy foods as a way to strengthen bones, has always been something of a mantra for the layman and nutritionist worried about the risks of developing osteoporosis in later life.

But recent research has raised questions about the benefits of milk, yoghurt and cheese on bone health.

A report in the latest issue of Pediatrics suggests there is “scant evidence” that dairy intake has much effect on promoting strong bones. The report’s authors — who are researchers on the Physicians’ Committee for Responsible Medicine (PCRM) in Washington — based their findings on a review of 37 studies; 27 of the studies showed no relationship between dairy foods or dietary calcium and bone health in children and young adults, while the remainder found only a small association. This led researchers to conclude that “under scientific scrutiny, the support for the milk myth crumbles”.

According to Dr Amy Joy Lanou, a nutritionist in the PCRM team, calcium, of which dairy food is a source, does play an important role in the development of bones. But Dr Lanou says their findings showed that physical activity during the peak years of bone growth (between birth and the early twenties) is a far stronger indicator of a strong skeleton in adulthood than dairy consumption. “It is really important for parents to understand that milk is not a necessary food for young people,” she says. “If children can’t drink milk for health or other reasons, their bones are still going to be just fine.”

There is no denying that osteoporosis is an increasing problem. One woman in three and one man in 12 over the age of 50 in the UK is affected, at a cost to the NHS of some £1.7 billion a year. Every three minutes someone suffers a fracture, usually to the hip, wrist or spine, because of the condition. According to the National Osteoporosis Society, prevention should begin in childhood with regular exercise and a diet that, where appropriate, includes dairy products. Current government recommendations state that anyone over 19 should aim to consume 700mg a day of calcium, with milk, yoghurt and cheese highlighted as important sources. Daily amounts for children vary according to age.

However, other experts suggest that the emphasis on dairy foods is overplayed, and point out instead the importance of other factors, including weight-bearing exercise, genetics, smoking, protein consumption and an adequate intake of vitamin D.

Professor Walter Willett, head of nutrition at Harvard University School of Public Health and the principal investigator in the Nurses’ Health Study (which has followed the diet and lifestyle habits of 72,000 women for 25 years), says that there is “no solid evidence that merely increasing the amount of milk in your diet will protect you from breaking a hip or crushing a backbone in later years.”

Professor Willett found instead that women who drank a glass of milk twice a day for many years were as likely to a suffer broken bone as those who drank only a glass a week. In a separate study of 43,000 men, the Harvard research team also failed to link long-term low-dairy consumption with brittle bones.

It has also been suggested that dairy foods and meat can even promote a leaching of calcium from the bones. According to Professor Colin Campbell, of the department of nutritional biochemistry at Cornell University, these foods contain good amounts of animal protein, which makes blood more acidic; the body tries to neutralise this by drawing calcium from the bones.

Professor Campbell argues that the more dairy people eat, the more calcium they will need to consume to balance these losses. His research has shown that in Asian countries, where dairy intakes are low, their populations suffer one fifth fewer broken bones than in Britain or America. “Those countries that use the most cows’ milk and its related products have the highest fracture rates and the worst bone health,” he says.

Bridget McKevith, a nutrition scientist for the British Nutrition Foundation, says that adults and children need no more than 0.8g of protein per kilogram of bodyweight every day, the equivalent of two servings.

“Too high an intake of animal protein is known to affect bone health adversely,” she says. “The same is true of highly processed foods and products that cause high levels of acidity, such as fizzy drinks.”

But McKevith and the majority of nutritionists remain cautious about the suggestion emerging from this research that it may be time to “ditch the dairy”, because full-fat milk is a “convenient source” of fat and calories for children under 12.

“Some calcium is essential in the diet,” she adds, “and dairy remains a useful way to get it, although it is not the only step we should take to protect our bones.”

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