EDITOR, - Sean Murphy and colleagues concluded that milk consumption should be encouraged during childhood and adolescence to prevent osteoporotic fractures in later life.1 This, however, prompts several questions. Firstly, the subjects in the authors' study were asked to categorise their milk consumption without estimating their past total calcium intake. It is known that many subjects who do not drink milk consume other dairy products (cheese and ice cream). Secondly, the subjects had to recall their milk consumption up to age 25, which was a long time before the study (50 years for the 74 year old woman). It could as well be concluded that good memory makes strong bones or vice versa.

If the results are reliable they lead to an interesting speculation. It is known that calcium supplementation increases bone mass in childhood.2 This does not occur later in life. Might calcium, or some other agent in dairy products, affect the developing bone in a way that later in life allows calcium intake and maintains high mineral density?

I strongly disagree with the public health implications cited by Murphy and colleagues. Dietary habits are learnt in childhood and adolescence and commonly …