Cancer is responsible for more deaths annually in the United Kingdom than is ischaemic heart disease. Around half of cancer deaths are due to tumours at four principal sites: lung, bowel, breast, and prostate. These cancers are virtually absent in many countries in the developing world but increase in incidence within one or two generations when migrants move from low to high risk areas.1 Thus many cancers common in Western populations are due to environmental factors, and these cancers should be largely preventable.

Diet is one of the most important lifestyle factors and has been estimated to account for up to 80% of cancers of the large bowel, breast, and prostate. 2 3 Even lung cancer may have a dietary component, although cigarette smoking is the overwhelming cause of this and contributes also to oropharyngeal, oesophageal, and bladder cancer. Physical activity, reproductive and sexual behaviour, infection with hepatitis B and C viruses, infection with helicobacter, and exposure to sunlight, ionising radiation, and environmental chemicals are also important at particular sites. Nevertheless, food and drink has a part to play in many if not all cancers, albeit to a variable extent.