A paper titled "Diet, nutrition and the prevention of cancer"(Key TJ et al. Public Health Nutr. 2004 Feb; 7(1A):187-200) provides a good view of the current state of knowledge on diet and cancer. Here are the summarized analysis and recommendations from this study:
1. Try to maintain body mass index (BMI) in the range of 18.5–25.0 kg/m2, and avoid weight gain in adulthood, which can avoid the risk for cancers of the esophagus, colorectum, breast (postmenopausal), endometrium, and kidney due to the obesity.
2. It is necessary to engage in regular physical activity to reduce the risk for colorectal cancer and probably the risk for breast cancer.
3. Drinking of alcoholic beverages is not recommended: if consumed, do not exceed 2 units/d (1 unit is equivalent to approximately 10 g of alcohol and is provided by one glass of beer, wine or spirits). Alcohol causes cancers of the oral cavity, pharynx, oesophagus and liver, and a small increase in the risk for breast cancer.
4. Aflatoxin in foods will cause liver cancer, to which the exposure should be minimized.
5. Chinese-style salted fish increases the risk for nasopharyngeal cancer and should only be eaten in moderation, especially during childhood. Overall consumption of salt-preserved foods and salted fish should be moderate.
6. It is necessary to have a diet which includes at least 400 g/d of total fruit and vegetables, which probably reduce the risk for cancers of the oral cavity, esophagus, stomach and colorectum.
7. Those who are not vegetarian are advised to moderate consumption of preserved meat (e.g. sausages, salami, bacon, ham etc.) and red meat (e.g. beef, pork, lamb). Preserved meat and red meat probably increase the risk for colorectal cancer. Salt preserved foods and high salt intake probably increase the risk for stomach cancer. Poultry and fish (except Chinese-style salted fish, see 5. above) have been studied and found not to be associated with increased cancer risk.
8. Do not consume foods or drinks when they are at a very hot (scalding hot) temperature, which probably increase the risk for cancers of the oral cavity, pharynx and esophagus.