ABSTRACT
Migrating populations have a particular fascination for epidemiologists and amongst the most studied migrants are a group of ethnic Japanese in Hawaii. They were originally chosen to throw light on how affluence and modernity cause heart attacks, with the expectation that their mortality from ‘diseases of affluence’ would rise with increasing exposure to the American way of life. Things turned out differently, for although there was some rise in heart disease mortality rates towards that of the host population up until the 1960s, rates then fell in parallel with the decline in rates throughout the US. The death rate from all causes in Hawaiian Japanese around 1980 was some 20 per cent lower than the rates of Japan, which were substantially lower than those in the US.1 The interesting question is no longer ‘how are they harmed’, but rather ‘what protects them’? Numerous studies have tried, with limited success, to identify the sources-genetic, behavioural, environmental or a combination of these-of their low mortality.2
