Introduction

Cancer is the second leading cause of death globally and is responsible for an estimated 9.6 million deaths in 2018. Globally, about 1 in 6 deaths is due to cancer. Cancer is a generic term for a large group of diseases that can affect any part of the body. It is postulated that 80 percent of cancer may be due to environmental factors, and it is possible that some dietetic factors may be involved. Some of the existing knowledge about nutritional factors and cancer are:

Alcohol: Heavy drinking increase the risk of liver cancer. It is estimated that alcohol contributes to about 3% of all cancer deaths. Some recent studies have suggested that beer consumption may be related to cancer rectum, but the association has not been confirmed.

Dietary fat: Population surveys have shown a strong positive correlation between cancer colon and dietary intake of fat. It has been suggested that high fat intake accounts for the high incidence of colon cancer in Western communities. In Japan, recent increases in fat consumption have been associated with a striking increase in rates of colon cancer. Dietary fat is believed to increase the secretion of bile acids in the bowl which is then metabolized by bacterial flora into carcinogen or co-carcinogens. However, no known carcinogen has yet been identified from faeces and the evidence is thus incomplete.

Dietary fibre: Several studies indicate that the risk of colon cancer is inversely related to the consumption of dietary fibre, which may protect against intestinal carcinogens or precursors by dilutional or other effects. Although the available epidemiological data are not entirely consistent, the weight of evidence generally supports the hypothesis that fibre protects against colon cancer.

Micronutrients: Micronutrients may have a protective influence, since cancers of the lung and several other sites have been associated with a low intake of vitamin A. The risk of stomach cancer has been related to a deficiency of vitamin C, which may act by inhibiting the formation carcinogenic nitrosamines in the stomach. Trace elements have also been implicated in the aetiology of cancer.

Food additive and contaminants: Food additives and contaminants have always been under suspicion as possible carcinogens in their long-term effects. Food processing involves exposure to high temperature, oxidation polymerization, production of nitrosamines, polycyclic aromatic hydrocarbons, etc which are injurious to health. It is thought in some quarters that nitrosamines are responsible for certain types of gastric carcinoma. Saccharin and cyclamate are weak bladder carcinogens or co-carcinogens in laboratory animals, but the risk in man is very small if present at all. Aflatoxin is a carcinogenic metabolite. Coffee intake has been associated with bladder cancer and recently with pancreatic cancer but causal relationships has not been established. The mutagenic properties of food additives are under constant surveillance.

Reference:

Willet, W.C. and B. MacMahon. N.Eng.J.Med., 310(11) 697
Park’s Textbook of Preventive and Social Medicine, K. Park: 23^rd Edition ; Assessment of Nutritional Status: Pg (647-648).
Wynder, E.L. and Hill, P.Lancet, 2:840-841
WHO