Diet and Cancer

“Doc, one more column on nutrition and I will throw up!” says Dave.

“Dr. B, just ignore him. Tell me, how can good nutrition prevent cancer?” asks Susan.

Susan, this question has been bothering me too. So, let us see if there is any scientific literature to prove that good nutrition can prevent cancer.

Here are two articles. First one, a review article titled “Diet and the prevention of cancer” in the British Medical Journal. Second one, “Diet and cancer” in the Encyclopaedia Britannica. This is what they have to say.

There are three ways in which a person’s usual diet may lead to cancer: (1) A cancer producing substance, in food or drink, can come in contact with the lining of the mouth, throat, oesophagus, stomach, intestines, liver, or urinary bladder and trigger changes leading to cancer. (2) A person is little overfed or a little underfed may influence the incidence of hormone-dependent cancers in the breast, uterus or prostate by altering the hormone secretion or metabolism. (3) Some nutrients may influence the susceptibility of other sites to cancer producing substances.

It has been estimated that diet may be responsible for around 38 percent of cancer deaths. About 80 percent of cancers of the large bowel, breast and prostate may be related to diet. One of the articles says: While there is strong but indirect epidemiological evidence that most of the common cancers could be made less common by suitable modifications of food habits, there is still no precise and reliable evidence as to exactly what dietary changes would be of major importance.

For people like you and me this creates a significant dilemma. We need to know exactly what to eat and what to avoid to prevent cancer. Just like the “heart smart” diets where we know the type of foods that will keep our heart and blood vessels healthy.

Colon and rectal cancer is one for which the evidence that diet is involved is probably strongest. Constipation is known to be a risk factor because of the increased time the cancer inducing substances in the stool spend against the lining of the colon and rectum. Increased intake of fibre and vegetables can hasten the transit time and reduce the risk.

Red meat , processed meat, and canned meat increase the risk of colon and rectal cancer.

When it comes to breast cancer, overweight postmenopausal women have up to a twofold greater risk. In premenopausal women, the effect of weight is inconsistent. Meat and alcohol are associated with increased risk. Low intake of vegetables and fibre may have the same effect.

Other cancers where nutrition is important are: cancer of the prostate, stomach, oesophagus, pancreas, lung, and uterus. The common theme is – excessive use of cigarettes, alcohol, meat, and fat. Not enough intake of fruits, vegetables, fibre, and certain types of vitamins.

Role of vitamins in cancer is controversial. Some experts believe that caution should be used with high doses of purified supplements of vitamins and minerals. But all experts believe that vegetables and fruits have strong protective effect and red meat and processed meat is linked to high risk of many cancers.

So next time you buy a burger, don’t ask: Where is the beef?


This series of articles explore the health problems of Dave and his family. They are composite characters of a typical family with health problems.

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