A review in this week's issue of The Lancet assessing the research to-date on possible links between diet and cancer reaches a familiar conclusion - cancer risk can be reduced by eating a balanced diet (with regular consumption of fresh fruit and vegetables), combined with regular exercise and a restriction on alcohol intake.
Diet-related factors are thought to be second only to tobacco in causes of cancer - accounting for about 30 per cent of cancers in developed countries - but there has been a lack of established evidence of specific dietary determinants of cancer risk said researchers.
Timothy Key and colleagues from the Cancer Research UK Epidemiology Unit at Oxford, UK, discussed a range of cancers that are associated with dietary factors. Obesity increases the risk of cancers in the oesophagus, colorectum, breast, endometrium, and kidney find the researchers, while alcohol causes cancers of the oral cavity, pharynx, larynx, oesophagus, and liver, and brings a small increase in the risk of breast cancer.
Key commented: "Despite extensive research during the last 30 years, few specific dietary determinants of cancer risk have been established, even for cancers such as colorectal cancer for which most researchers agree that diet probably has important effects. "
He continued: "The main factors that have held back progress are the inaccuracy of methods for estimating food and nutrient intake and the biases in case-control studies. The results of existing large prospective studies and controlled trials should substantially advance our understanding of the role of diet in cancer during the next few years.
At present, prudent advice is to maintain a healthy weight, restrict alcohol consumption, and select a conventionally balanced diet ensuring an adequate intake of fruit, vegetables, and cereals."