Truswell’s recent review of the A1/A2 milk hypothesis in this journal (Truswell, 2005) is very clear in its conclusion that『there is no convincing or even probable evidence that the A1 b-casein of cow milk has any adverse effects in humans』. The basis on which this conclusion is reached needs scrutiny. 

There are seven strands off evidence relevant to the A1/A2 hypothesis: epidemiology, milk chemistry, pharmacology, animal experiments, human trials, clinical observations, and consumer experiences. It is the totality of these seven strands that makes the A2 hypothesis so intriguing.