Most of cancer in humans are caused by food-related factors. The cancer-causing agents, known as carcinogens may be present in the food as such or may be produced during the process of cooking and storing of the food. The bitter-tasting cereals, nuts, and corn may contain aflatoxins, which are broken down into epoxide in the liver. The epoxide is a highly carcinogenic agent that remains in the body for a very short period but this duration is sufficient for it to damage the cellular DNA. Aflatoxins are known to cause cancers of the liver, stomach and the kidney. Nutritional imbalances are also known to cause cancer, for example, todayâ€™s fast food, which is rich in sodium and cholesterol but poor in fiber, vitamins, and calcium, may lead to cancer.
Grilled, tandoori and fried food contain certain polycyclic aromatic hydrocarbons that may cause cancer by damaging the DNA. In China, the incidence of the stomach and the oesophageal cancer is much higher, probably due to excessive consumption of smoked and pickled food that contain several carcinogenic substances. Some carcinogens are produced when meat, poultry, and fish are fried, broiled, grilled or barbecued at a higher temperature for longer periods. It has been observed that the fried and broiled meat contain a much higher content of mutagens. A recent study has revealed that about 20 percent non-vegetarians have toxic mutagens in their digestive tract.
Excessive consumption of the animal protein produces a large number of nitrogenous wastes in the intestine that get converted into highly carcinogenic compounds called nitrosamines, which are known to cause many cancers including those of the breast, colon, pancreas, kidney, prostate and the uterus. Studies conducted in the U.S.A. have revealed that those persons, who consume red meat, have a twofold higher risk of breast cancer and a threefold higher risk of prostate cancer. Another study has shown that there is a higher incidence of colon cancer in those persons who consume beef, pork or lamb meat.
Excessive consumption of fat, particularly the animal fat may cause cancers of the breast, colon, rectum, uterus, prostate and the kidney. On the other hand, a low intake of fat reduces the risk of cancer. Most of the consumed animal fat such as meat & egg and most of the dairy products belong to the omega-6 class that acts as cancer promoter by suppressing the immune system of the body and generating free radicals (highly reactive, unstable molecules that promote the growth of cancer). The fried, creamy and oily food also belongs to the omega-6 class. On the other hand, the fat found in fish and vegetables (such as oils of safflower, sunflower, flaxseed, sesame, walnut, corn and pumpkin seed) belongs to the omega-3 class, which is beneficial to human health. Omega-3 fatty acids promote the production of the good eicosanoids (such as PGE-1) and prevent the synthesis of the bad eicosanoids (such as PGE-2). It is worth mentioning here that the omega-3 fatty acids synthesize PGE-1 in presence of certain co-factors such as zinc, niacin, pyridoxine and ascorbic acid. A study conducted in the USA on 429 non-smoking lung cancer patients for 6 years has revealed that excessive intake of the saturated fat is one of the major causes of lung cancer in non-smokers.
[Eicosanoids are hormones like substances produced from arachidonic acid and some other fatty acids. The good eicosanoids improve immunity and overall health, while the bad eicosanoids promote genesis as well as the growth of cancer by stimulating the inflammatory process, enhancing proliferation of the cancerous cells and paralyzing the immune cells of the body].
The consumption of contaminated fish may cause cancer in human beings. Industrial and agricultural pollutants such as polychlorinated biphenyls (PCBs), methyl mercury and hydrocyanic acid may enter the fish through the food chain and get accumulated. Methyl mercury is known to cause cancer by suppressing the activity of the immune cells. Studies have revealed that PCBs may cause cancer in human beings even in a very small quantity.
Recombinant Bovine Growth Hormone (rBGH) injections are routinely given to the dairy cows to increase their milk yield. Consumption of the milk from rBGH treated cows may cause cancer, particularly breast cancer. Similarly, consumption of dairy products and the meat contaminated with steroids may lead to cancer.
Excessive consumption of sugar and other refined carbohydrates create favorable conditions for tumours to grow by lowering the oxygen level in the tissues. Sugar also stimulates the production of PGE-2 in the body that further promotes the growth of cancer. Consumption of sugar stimulates the production of insulin that in turn promotes the growth of cancer. Sugar is also known to suppress the activity of the immune cells in the body. It has been observed that after consuming 100 grams of sugar, the working capacity of the white blood cells is reduced by 35 percent for at least 2 hours. This immunosuppressive action starts within 30 minutes after taking sugar and lasts up to 5 hours.
Most of the food additives including preservatives, sweeteners, and colorants are found to have carcinogenic activity. Butylated hydroxytoluene, used as a preservative, is known to cause liver cancer. Saccharin and cyclamates, used as artificial sweeteners, may cause cancer of the bladder. Another artificial sweetener, Aspartame, is known to cause the brain tumours. There are many other food additives including Blue Dye No. 2, Red Dye No. 3, Gentian violet, Propyl gallate, Nitrofurans, and Aldicarb, which may lead to the genesis of cancer.
Consumption of irradiated food may cause cancer. Irradiation of food is done to extend its shelf life by killing insects, bacteria, moulds, and fungi. During the process of irradiation, the food is exposed to radioactive substances such as caesium-137 and cobalt-60. The irradiation of food may produce certain toxic substances such as formaldehyde and benzene. It also increases the level of aflatoxins in the food. When the residual contents of herbicides, insecticides, pesticides, fungicides, colorants, antibiotics, steroids, preservatives and stabilizers, present in the food, are irradiated, these get transformed into certain toxic radioactive products known as unique radioactive products (URPs), which are highly carcinogenic.
Alcohol stimulates the growth of cancer by suppressing the activity of the natural killer cells (NK cells). Alcohol may lead to the genesis of many cancers including those of the breast, mouth, throat, oesophagus, pancreas and the liver.
Excessive intake of caffeine (coffee, tea, cola, and chocolate) may cause cancer of the urinary tract. Caffeine causes cancer by damaging the DNA as well as by impairing the natural DNA repair mechanism of the body.
Iron promotes the growth of cancer by producing free radicals. Studies have revealed that even a moderate accumulation of iron in the body enhances the risk of cancer.
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