International differences in coronary heart disease mortality and consumption of fish and other foodstuffs.

The relationship between fish consumption and coronary heart disease mortality was investigated using data on foodstuff consumption and mortality from 21 countries. A moderate negative association was found which appeared stable over different periods. This association disappeared when the effects of other foodstuffs were controlled for in multiple regression analysis. One feature to emerge was the anomalous position of Japan in consumption of several foodstuffs. Inclusive or exclusion of this country from regression analysis had a powerful effect on which independent variables entered the model. This illustrates the danger of using single countries, for example Japan with a high fish consumption and low CHD mortality, to support causal hypotheses about diet and disease.