We are frequently bombarded with information about "cancer-causing" or "cancer-curing" foods. And while there is no such thing as the latter, research has highlighted nutritional components that, in addition to other factors, can influence your cancer risk.

Certain types of cancer are more affected by diet, and these tend to be cancers of the digestive tract which come into direct contact with food such as the mouth, throat, stomach and bowel.

A hearty fruit and vegetable intake decreases risk of both stomach and throat cancer, which may be due to the protective effects of anti-oxidant vitamins. Fruit and vegetables contain other components such as folate, phytonutrients and plenty of fiber, which may play a role.

The European Prospective Investigation of Cancer (EPIC), a huge study ongoing in Europe, has found that an intake of 35g of fiber per day (equivalent to 7 portions of fruit and vegetables and 5 slices of wholemeal bread) can lead to a 40 percent reduction in colon cancer risk. A generous intake of milk, cheese and high overall calcium intake also seems to reduce this risk.

Studies of Chinese populations have also shown some interesting relationships. A Shanghai study published in 2005 found foods from the Allium family (such as onions and garlic) have been shown to greatly reduce the risk of stomach cancer. More recently this has been corroborated in an Italian study which also showed a protective effect against other cancers including mouth, throat, colon and prostate.

Another study carried out among Chinese patients in Australia found the regular green tea consumption reduced the risk of ovarian cancer in women, with those that had been sipping it daily for 30 years having only 23 percent of the risk of those that had not. In fact the polyphenols in both black and green tea can help to detoxify cancer-causing substances, and also to slow the rate of cancer cell development

Unfortunately the adjustment to a more Western style of eating in China, with an increase in meats and sweets has had a negative impact on cancer incidence. Older Chinese women that have taken on Western eating habits are more likely to develop breast cancer than those with a more traditional vegetable and soy-based diet. This may be partially associated with obesity, but also the changes in food itself.

A large study published in 2005, called the China Study also found evidence to support the connection of high red meat consumption to colon cancer risk. This risk is even greater if burnt or charred meat is frequently consumed due to the action of heterocyclic amines, compounds which are capable of mutating cells in the body. Boiling or stewing may well be the safest way to eat meat.

This nutrition-related column is written by Nina Lenton, a qualified dietitian living in Beijing and working at Bayley and Jackson Medical Center. Contact her at nina.lenton@bjhealthcare.com.

(China Daily 09/06/2007 page14)