With the potential for cancer looming in the background, it's important to understand which foods may increase the risk of different types of cancer. Eating a diet rich in whole, non-starchy vegetables and fruits is likely to reduce the risk. When it comes to carcinogenic foods, there aren't many that can be definitively linked to cancer. However, research has found that consuming red and processed meat may increase the risk of bowel cancer.
The World Health Organization (WHO) has classified processed meat as a Group 1 carcinogen, specifically related to colorectal and stomach cancer. Red meat is classified as Group 2A, probably carcinogenic to humans, with the strongest link between red meat consumption and colorectal cancer. There is also evidence of links to both pancreatic and prostate cancers. To reduce the risk of cancer, the Cancer Council recommends limiting consumption of cooked red meat to 65-100g per week.
Alcohol consumption should also be reduced as much as possible, as it is classified as a Group 1 carcinogen, related to cancers of the mouth, throat, esophagus, breast, liver, stomach and intestine. The cancer risk associated with alcohol is thought to be dose-dependent in some forms of cancer. However, a study suggests that moderate consumption of red wine may be related to lower overall mortality and a lower risk of coronary heart disease and stroke. Chinese-style salted fish is another Group 1 carcinogen like processed meat.
Tomatoes contain high amounts of lycopene, a chemical that offers “moderate protection” against prostate cancer for those who consume large quantities of raw tomatoes. Eating citrus fruits can significantly reduce the risk of esophageal and pancreatic cancer, with a high intake (at least three servings per week) reducing the risk of stomach cancer by 28%. The Global Fund for Cancer Research suggests that high-dose dietary supplements are not recommended for cancer prevention, and that the best approach to preventing cancer is to try to meet nutritional needs through whole foods. No single food can prevent cancer, but eating whole foods that are high in fiber reduces the risk of bowel cancer.
The Australian Guide to Healthy Eating recommends eating a variety of foods from the food group (lean meats and poultry), fish, eggs, tofu, nuts and seeds, legumes and beans. While food plays an important role in preventing some types of cancer, the therapeutic value of food for treating existing cancers is less clear.