Increases in bone density may be result of micronutrients in additional cereal

EDITOR—Cadogan et al reported the effect of increased milk intake on bone mineral acquisition in English schoolgirls.1 The results of their study have important implications for childhood dietary policy. We are concerned, however, that the results may be confounded by associated changes in dietary intake. We noted comments made by a participant in the study on a BBC news item that she consumed her additional milk with extra cereal.

Most cereals available in the United Kingdom are supplemented with a variety of vitamins and minerals. Furthermore, there is evidence in the literature that these micronutrients are important to bone health,2 and the effect observed may therefore reflect in part the additional micronutrient intake from this source. Indeed, the intake of phosphorus, magnesium, zinc, and vitamins B-1 and B-2 were higher in the milk supplemented group. This may not be solely attributable to the milk.

Details of how the milk was consumed are not given in the paper, but the data should be available from the interim food diaries recording non-weighed food intake over four days that subjects completed on five interim occasions. It would be interesting and important for these …