This week, the World Cancer Research Fund (WCRF) launches its second report on diet and cancer through simultaneous conferences in London and Washington. Entitled Food, Nutrition, Physical Activity, and the Prevention of Cancer, the report updates the previous publication from the charity. It is the culmination of five years' work by scientists in nine universities from four countries who have assessed the original research according to a specially developed standardised review protocol.1

The possible influence of diet on the risk of cancer is constantly topical. The subject is important because people can change their diets, and even a moderate effect on risk could prevent several thousand cancers each year in a country the size of the United Kingdom. However, apart from the confirmed adverse effects of alcohol and obesity on the risk for some types of cancer,2 3 4 5 progress in understanding has been slow and the evidence remains confusing.

The conclusions in the WCRF report about the effects of obesity and alcohol are similar to those reached by other expert consultations.1 2 3 4 5 Obesity increases the risk of cancer of the oesophagus, colorectum, pancreas, breast, endometrium, and kidney. The report's public health goal for obesity is for the median body mass …