Milk… Is it worthy of the tag line “what more can a body ask for?”
The human health benefits (or disbenefits) of milk and dairy products continue to grab the headlines. Recently the media reported on a study in the British Medical Journal relating milk intake (liquid and products) to the risk of bone fractures and mortality in men and women. So is this the final evidence that means school milk will never darken our doors again? Well the answer to that would appear to be no, and on the whole the press coverage of the original study was fair and balanced. The reports point to one of the main conclusions that drinking (a lot) of milk may have some health risks with the headlines ranging from Milk might not be as good for us as we thought to Three glasses of milk a day can lead to early death. In reality the most accurate of the headlines reporting this study was High milk diet ‘may not cut risk of bone fractures’.
The study was based on analysis of two large Swedish cohort studies (one male and one female). The average frequency of consuming up to 96 food and beverages (including drinking liquid milk and fermented dairy products such as yogurt and cheese) was self reported by the participants. These food frequency results were aligned with records for health outcomes and death (and the causes of death), including clinical measurements on subsamples. Some of the key results in the paper showed a positive association of milk intake with mortality (in men and women) and bone fracture (in women only), that is, more those consuming more milk had poorer outcomes. In contrast the study also showed that women with a higher rate of consumption of fermented milk/dairy products had lower mortality and fracture rates.
All of the previously mentioned news articles reported these main results but also highlighted that they should be treated with some caution and not be the basis for changing dietary guidelines. So although to be commended for their cautious approach in the interpretation of the results, a few further highlighted the potential influence of other factors such as smoking, alcohol and weight. For example, the BBC picked up on a suggested link the study made that some “sugars in milk … have been shown to accelerate ageing in some early animal studies” and that this might be a potential mechanism that underlies the reported associations in this study. However, this study does not show any causal link between the constituents of different types of milk and dairy products, and the consumption thereof, with any subsequent fracture or mortality risk. There was no data on the make-up of the dairy products considered in the study.
In presenting the main results, to a lesser or a greater extent all articles quoted the authors and/or other experts in highlighting the importance of a balanced diet and the role of dairy within that; so in that regard there is probably little chance of a knee jerk reaction by consumers.
Michaëlsson, K. et al. (2014). Milk intake and risk of mortality and fractures in women and men: cohort studies. British Medical Journal. DOI:110.1136/bmj.g6015