How healthy living could reduce cancer risk
Very few specific foods or drinks have been convincingly shown to raise or lower the risk of cancer. This is because our diets consist of many different foods, nutrients and chemicals that could affect our risk of cancer.
It is very difficult to design studies that accurately look at the effect of a single food item or nutrient. This section will tell you about foods that are linked to cancer risk by strong scientific evidence.
Research suggests nearly one in 20 cancers in the UK may be linked to diets low in fruit and vegetables. Eating lots of fruits and vegetables has been linked to a lower risk of cancer of the mouth, oesophagus (food pipe), lung, larynx (voice box) and some types of stomach cancer.
Fruit and vegetables are an important part of a healthy diet and are an excellent source of many vitamins and minerals, as well as fibre.
Fruits and vegetables contain a wide variety of different nutrients that have many different effects on the body. These nutrients include carotenoids, folate, vitamin C, vitamin E, selenium, flavonoids and various other phytochemicals (chemicals found in plants). Some of these may be linked to reduced cancer risk by things like:
- mopping up harmful chemicals that could potentially damage DNA
- helping protect against DNA damage
- helping with repairing DNA
- blocking the formation of cancer-causing chemicals
Red meat includes all fresh, minced and frozen beef, pork and lamb. Processed meat includes ham, bacon, salami and sausages. White meat, such as chicken, is unlikely to increase the risk of cancer.
Scientists think there are a number of ways in which red and processed meat can increase the risk of cancer – they involve the chemicals found in these meats. Some chemicals are a natural part of the meat, and others are made when the meat is preserved or cooked at high temperatures.
Red and processed meats contain a red pigment called haem. Haem could irritate or damage cells in the bowel or fuel the production of harmful chemicals by bacteria in the gut, which could lead to a higher risk of cancer developing. Almost all red and processed meats contain greater amounts of haem than white meats. This may partly explain why red and processed meats increase cancer risk while white meats don’t.
Chemicals called nitrates and nitrites are often used to preserve processed meat. In the bowel nitrites can be converted into cancer causing-chemicals called N-nitroso compounds (NOCs). The presence of these chemicals may explain why many studies have found that processed meat increases the risk of cancer to a greater extent than red meat.
Cooking meat at high temperatures such as grilling or barbecuing can produce cancer-causing chemicals called heterocyclic amines (HCAs) and polycyclic amines (PCAs).
The presence of these chemicals may explain why some studies find that meat cooked at high temperatures might increase the risk of bowel cancer to a larger extent than meats cooked at lower temperatures such as boiling or braising.
We’ve written in more detail about the ways in which red and processed meat could increase the risk of cancer on our blog.
Much research has shown that bowel cancer is less common in people who eat lots of fibre. Fibre could help protect against bowel cancer in a number of ways.
Fibre increases the size of stools, dilutes their contents, and helps people have more frequent bowel movements. This reduces the contact time between the bowel and harmful chemicals in the stools. Fibre may also help gut bacteria to produce helpful chemicals that change the conditions in the bowel. All of these things help to reduce the risk of cancer.
Eating too much salt, or lots of foods high in salt, has been linked with a higher risk of stomach cancer.
Salt could increase cancer risk by damaging the stomach lining causing inflammation, or by making the stomach lining more sensitive to cancer-causing chemicals.
Salt could also interact with a stomach bug called Helicobacter pylori that is linked to both stomach ulcers and stomach cancer.
Question about cancer? Contact our information nurse team