Food Health Nutrition and cancer

Press, 28 March 1981, Page 10

Food Health Nutrition and cancer

A review in two parts by Prof. DON BEAVEN

All cells in the body divide and replace, themselves.

, This cell division and replacement goes on throughout the body during life. With increasing age, more and more divisions have taken place and thus the chance of some abnormal division becomes greater. As a cell divides the essential genetic material is then at risk from outside influences — well-accepted influences such as natural or cosmic radiation, and X-rays used for both diagnosis and treatment.

Such dividing cells could, theoretically, be influenced by any chemical substances which can enter the cell from the bloodstream. Most such chemicals are eaten as part of our food, or are in the fluids we drink. When cell divisions are altered or disrupted at the moment of division by abnormal radiation or excess chemicals not normally found in the cell, an abnormal cell results. If an abnormal cell which has no regulators for division and growth is produced, it could go on to form a rapid accumulation of abnormal cells, or a small cancer.

Such abnormal, or mutant, cells are being formed all the time. But they are being attacked and destroyed by special cells in the body which patrol about, awaiting the emergence of such mutant cells. Some mutant cells are good, and allow a slow change and adaptation to our environment over several thousands of generations. Later in life, there are more and more mutations. Many are harmful and potentially cancer-forming. If any escape destruction

by the patrol cells, or special lymphocytes, they will grow over many years to form a cancer able to be detected for the first time by doctors and scientists. These substances are called carcinogens. Some, such as mycotoxins from mouldy peanuts, may eventually give liver cancer. Some nitrosamines, when taken regularly in excess, will give cancer of the stomach. Professor Ernst Wynder, of the American Health Foundation, of New York, ■unlike so many “popular” medical authors in this field, is a top United States food scientist requested to publish a review for the prestigious, federation meeting of American Societies for Experimental Biology. Although he believes that 50 to 90 per cent of all cancers are related to our environment, he is not much impressed by arguments implicating food additives, except in rare and well-docu-mented instances. In Table 1 Professor Wynder lists associations of suspected nutritional deficiencies, or imbalances, leading to cancers:

After a full review he comments that studies are extremely difficult because animal models do not directly reflect the human setting. He makes a plea for more measurements from body fluids and tissues in groups of persons from populations with high and low, known, specific cancer rates. It is increasingly believed that the development of cancer appears to be related to an excess of nutrients. Although, until the. last few hundred years, most people died younger from food deficiencies and worn-out teeth, the suspected, nutritional-ex-cess cancers cannot all be accounted for by longer life span. Calorie excess on its own appears to be associated with an increase of kidney and uterus cancer in women. Professor Wynder discusses each of two major cancers in our New Zealand society, breast cancer in women and colon cancer in men. The results of these fascinating studies will be looked at in our next column, with some implications for the typical New Zealand diet.

TABLE 1 Suspected associations— Nutritional deficiencies or imbalances

Cancer in:— Iron (Plummer-Vinson) Upper G.I. tract Iodine (goitre) Thyroid Vitamin B2 (Alcoholism) Upper G.I. tract Vitamin A (low fat) Cervix stomach Pyridoxin Liver