Editor,—In a recent article on diet and colorectal cancer, Stoneham et al 1reported that 76% of the variation in incidence rates between 28 countries could be explained by three significant dietary factors (meat, fish, and olive oil). The authors concluded that olive oil may have a protective effect on the development of colorectal cancer. While a plausible mechanism is proposed, it is worth noting that 21 of the 28 populations included in the ecological study were essentially non-consumers of olive oil (<0.01 kg/year per capita) and the inverse association between consumption and colorectal cancer risk …