Most of the cancers are caused by food related factors. Certain foods contain carcinogens, while in some; carcinogens are produced during the process of cooking & storing. Nutritional imbalances are also known to cause cancer, for example, today's fast food, which is rich in sodium and cholesterol but poor in fibres, vitamins and calcium, can lead to the development of cancer.
Some bitter tasting cereals, peanuts and corn might contain Aflatoxins, which are broken down into Epoxide in the liver. Epoxide is a highly carcinogenic agent that remains in the body for a very short duration, but this period is sufficient for it to damage the cellular DNA. Aflatoxins can cause cancers of liver, stomach and kidney.
Grilled, tandoori and fried foods contain Polycyclic Aromatic Hydrocarbons along with some other toxins, which enhance the risk of cancer by damaging the DNA. In China, the incidence of stomach and oesophageal cancer is higher due to excessive consumption of smoked & pickled foods that contain several carcinogenic substances.
Excessive consumption of animal proteins produces large amounts of nitrogenous waste in the intestine that get converted into highly carcinogenic compounds called Nitrosamines, which are known to cause various cancers including those of the breast, colon, pancreas, kidney, prostate and uterus. Studies conducted in the U.S.A. have revealed that the persons consuming red meat have twofold higher risk of breast cancer in females and threefold higher risk of prostate cancer in males. Another study has shown that there is a higher incidence of colon cancer among the persons who consume beef, pork or lamb meat. Certain carcinogens are produced when meat, poultry and fish are fried, broiled, grilled or barbecued for longer periods at higher temperature. The fried and broiled meat have higher content of mutagens. A study conducted on non-vegetarians has shown that 20 percent of them have toxic mutagens in their digestive tract.
Excessive consumption of fat, particularly animal fat enhances the chance of damage to DNA, causing various cancers including those of the breast, colon, rectum, uterus, prostate and kidney. On the other hand, low intake of fat decreases the risk of cancer. Most of the consumed animal fat is of Omega-6 class, which acts as a cancer promoter by generating free radicals (highly reactive, unstable molecules that promote growth of cancer) and suppressing the immune system of the body. But the fat found in fish and vegetable oils (such as Corn, Safflower, Sunflower, Flaxseed, Sesame, Walnut and Pumpkin seed) is of Omega-3 class, which are beneficial to human health. Omega-3 fatty acids promote production of the good eicosanoids (such as PGE-1) and prevent synthesis of the bad eicosanoids (such as PGE-2). It is worth mentioning that Omega-3 fatty acids synthesise PGE-1 in the presence of certain co-factors like Zinc, Niacin, Pyridoxine and Ascorbic acid. By avoiding meat, eggs, fried foods, creamy sauces, oily dressings and other dairy products in the diet, one can get rid of bad eicosanoids. A study conducted in the USA on 429 non-smoking lung cancer patients for 6 years, has shown that the excessive dietary intake of saturated fat is one of the major causes of lung cancer.
Eicosanoids are hormone-like substances produced from Arachidonic acid & other fatty acids. The Good Eicosanoids improve immunity and overall health of a person. The Bad Eicosanoids promote genesis & growth of cancer by stimulating inflammatory processes, enhancing proliferation of the cancerous cells and paralysing immune cells of the body, especially the natural killer (NK) cells.
Consumption of contaminated fish can cause cancer. It has been observed that industrial and agricultural pollutants such as mercury, nickel and hydrocyanic acid get into the tissues of fish through the food chain. Other chemicals such as Polychlorinated biphenyls (PCBs) and Methyl mercury also get accumulated in fish. Studies have shown that Polychlorinated biphenyls can cause cancer in human beings, even in very small quantities. Methyl mercury decreases the activity of immune cells, thus predisposing the body to cancer.
The recombinant Bovine Growth Hormone (rBGH) injections are routinely used in dairy cows to increase the milk yield. The use of dairy milk from rBGH treated cows can cause cancer of the breast. Consumption of dairy products & meat contaminated with steroids and antibiotics is another risk factor of cancer.
Excessive consumption of sugar & other refined carbohydrates lowers oxygen level in the body thus creating a favourable condition for the tumour to grow. Sugar promotes the growth of cancer by stimulating PGE-2 production in the body. Sugar also reduces the activity of immune cells in the body. Studies have shown that after consuming 100 grams of sugar, working capacity of the white blood cells is reduced by 35 per cent for at least 2 hours. The immune suppressive action starts within 30 minutes of taking sugar and lasts up to 5 hours. It has been observed that consumption of sugar stimulates production of insulin in the body, which in turn promotes growth of cancer.
Most of the food additives like preservatives, sweeteners and colorants have carcinogenic activity. Butylated hydroxytoluene, used as a preservative, can cause cancer of the liver. Saccharin and Cyclamates, used as artificial sweeteners can cause cancer of the bladder. Another artificial sweetener called Aspartame is known to cause brain tumours. Other food additives, which are known to cause cancer, include Blue Dye No 2, Red Dye No. 3, Propyl gallate, Gentian violet, Nitro furans and Aldicarb.
Food irradiation can cause cancer. Irradiation of food is done to kill insects, bacteria, moulds and fungi with the aim to extend its shelf life. During the process of irradiation, food is exposed to radioactive substances such as Caesium-137 and Cobalt-60. The process of food irradiation can produce certain toxic substances (such as Benzene and Formaldehyde) in the food. Irradiation also increases the level of Aflatoxins (one of the major carcinogens) in the food. When the residual contents of herbicides, insecticides, pesticides, fungicides, colorants, antibiotics, steroids, preservatives and stabilisers present in the food are irradiated, these get transformed into certain toxic radioactive products known as Unique Radioactive Products (URPs), which are highly carcinogenic substances.
Alcohol stimulates the growth of cancer by suppressing the activity of the natural killer (NK) cells, leading to various cancers including those of the breast, mouth, throat, oesophagus, pancreas and liver.
Excessive intake of caffeine (found in coffee, tea, cola and chocolate) can cause cancer of the urinary tract. Caffeine damages the cellular DNA as well as impairs the natural DNA repair mechanism, thus enhancing the risk of cancer.
Iron promotes the growth of tumours by producing free radicals (highly reactive, unstable molecules that promote the growth of cancer). Recent research data has shown that even moderate accumulation of iron in the body enhances the risk of cancer.