The claims have been sensational. Martin Mittelstaedt checks up on the research behind the hype ### In the summer of 1974, brothers Frank and Cedric Garland had a heretical brainwave. The young epidemiologists were watching a presentation on death rates from cancer county by county across the United States. As they sat in a lecture hall at Johns Hopkins University in Baltimore looking at the colour-coded cancer maps, they noticed a striking pattern, with the map for colon cancer the most pronounced. Counties with high death rates were red; those with low rates were blue. Oddly, the nation was almost...