Role of Nutrition in Cancer Treatment

Nutrition plays an important role in the prevention and treatment of cancer. Nutrients provide essential nourishment to the body for the maintenance of life. These can be divided into two groups, i.e. energy nutrients and protector nutrients. Certain vitamins (such as B vitamins) and minerals (such as magnesium), which help in the process of conversion of food into energy by activating specific enzymes are called energy nutrients, whereas the nutrients that protect the body from various toxins (such as environmental pollutants) are known as protector nutrients. The protector nutrients include beta-carotene, vitamin C, vitamin E, copper, manganese, selenium and zinc. Most of the protector nutrients act as antioxidants by eliminating free radicals (which are highly reactive, unstable molecules produced during the process of conversion of food into energy). Some nutrients are known to perform specific functions in the body, for example, vitamin C, vitamin E and selenium protect the body from environmental pollutants while B vitamins counteract emotional and physical stress. The nutritional deficiencies may lead to the genesis of cancer by suppressing the immune system of the body and inducing premature ageing.

A vegetarian diet is rich in fibre, micronutrients and antioxidants. A study conducted on 1200 persons, all above the age of 66 years, has shown that the vegetarians have a significantly lower incidence of cancer as compared to the non-vegetarians. Another study conducted at the Institute for Experimental Pathology, German Cancer Research Center, Heidelberg, Germany has revealed that the blood samples of vegetarians contain higher levels of cancer-preventing factors such as carotene and glutamine transferase. Moreover, the activity of the natural killer cells (NK cells) is found to be twofold higher in the vegetarians as compared to the non-vegetarians.

Amino acids play an important role in the prevention and treatment of cancer. N-acetyl cysteine is a sulphur-containing amino acid that inhibits angiogenesis, enhances the immunity of the body and reduces toxic side effects of radiotherapy & chemotherapy. N-acetyl cysteine plays an important role in the synthesis of DNA and protects DNA from the damaging effect of free radicals. L-arginine, an amino acid, enhances the anticancer activity of the natural killer cells (NK cells) and the cytotoxic T lymphocytes (CTL). Another sulphur-containing amino acid, methionine, increases survival period in the liver cancer patients.

Coenzyme Q10 (Ubiquinone) prevents the genesis of cancer by enhancing the activity of the macrophages. A study done on advanced cases of breast cancer has shown partially to complete regression of the tumours after administration of Coenzyme Q10. It also protects tissues of the liver, kidney and the heart from the damaging effect of free radicals. Soya bean, grape seed, sesame seed, pistachio, walnut and spinach contain rich contents of coenzyme Q10.

Gamma-linolenic acid inhibits the growth of cancer by producing good eicosanoids such as PGE-1. This function of gamma-linolenic acid is promoted by vitamin B3, vitamin B6, vitamin C and zinc. Studies have shown that a combination of gamma-linolenic acid and vitamin C increases the survival period in liver cancer patients. Black currant oil, evening primrose oil and mother's milk contain rich contents of gamma-linolenic acid.

Beta-carotene, a precursor of vitamin A, increases the immunity of the body against cancer by enhancing the activity of the natural killer cells (NK cells). It also acts as an antioxidant. Beta-carotene protects the body against many cancers including those of the cervix, lung and the stomach. Most of the vegetables such as carrot, sweet potato, spinach and yellow coloured fruits contain rich contents of beta-carotene.

Vitamin A is known to enhance the activity of the immune cells of the body against cancer. A study conducted on patients of squamous cell carcinoma of the lung has shown significant regression of the tumours after administration of vitamin A for 15 months. Another study conducted on the patients of squamous cell carcinoma of the head and neck region has shown considerable regression of the tumours after administration of 13-cis-retinoic acid, which is a derivative of vitamin A. Vitamin A also protects the body against the malignant melanoma.

Vitamin B3 or Niacin (Nicotinic acid) enhances the therapeutic effect of radiotherapy and chemotherapy when given in doses of 50 mg daily. Asparagus, whole grain and brewer's yeast contain rich contents of Vitamin B3.

Vitamin B6 enhances the immunity of the body. It protects the respiratory tract from environmental pollutants and infections by keeping the mucous membrane in a healthier state. Vitamin B6 inhibits the growth of the liver and cervical cancers. It also protects the body from toxic side effects of radiotherapy. Studies conducted on 33 patients of the bladder cancer have shown that there was a considerably lower incidence of recurrence after administration of vitamin B6. Banana, apple, carrot, sweet potato and leafy green vegetables contain rich contents of Vitamin B6.

Vitamin C enhances the immunity of the body by boosting the production of interferon and stimulating the natural killer cells (NK cells). It inhibits the growth of cancer by blocking the production of nitrosamines. Vitamin C protects the body from toxic side effects of chemotherapy and radiotherapy. Studies done in Scotland and Canada have shown that vitamin C prolongs the survival period and improves the quality of life in terminal cases of cancer. Vitamin C also prevents the direct spread of cancer by stabilising and strengthening connective tissue around the tumour. Vitamin C is found in many fruits and vegetables including citrus fruit, broccoli and green pepper.

Vitamin D and its metabolites prevent the growth of cancer by inhibiting angiogenesis and promoting apoptosis in the cancerous cells. Vitamin D also induces conversion of cancerous cells to normal cells. The incidence of prostatic cancer is higher in Iceland, Denmark and Sweden due to the limited sunlight, leading to deficiency of vitamin D. Research done in Australia has confirmed the protective role of vitamin D against prostatic cancer.

Vitamin E protects the body from chemical carcinogens due to its strong antioxidant and detoxifying activities. A study conducted on the patients of oral leukoplakia has shown that 46 per cent of cases recovered fully after administration of vitamin E in doses of 400 IU twice daily for 24 weeks. Vitamin E protects the body against cancer, particularly colon cancer. It also reduces the toxic side effects of chemotherapy and radiotherapy. Dark green leafy vegetables, wheatgrass and unrefined vegetable oils contain rich contents of Vitamin E.

Folic acid plays an important role in the synthesis of DNA and protects the body against cancer, particularly cervical cancer. Cabbage, dark green leafy vegetables, citrus fruits and dairy products contain rich contents of folic acid.

Omega-3 fatty acids play an important role in the normal functioning of the human cells and protect the body from cancer by inhibiting the production of bad eicosanoids such as PGE-2. Omega-3 fatty acids are known to protect the body against cancers of the breast and the liver. Omega-3 fatty acids enhance the therapeutic effect of chemotherapy by altering cell membrane of the cancerous cells. Omega-3 fatty acids should be consumed in a moderate quantity and that too along with an adequate amount of antioxidants because excessive consumption of any type of fat enhances the risk of cancer. Fish and plant oils such as flaxseed, pumpkin seed, corn, safflower, sunflower and walnut contain rich contents of omega-3 fatty acids.

Genistein and daidzein are natural oestrogens found in legumes, especially soya bean. Genistein and daidzein inhibit the growth of hormone-dependent cancers by blocking oestrogen. Studies have confirmed that genistein prevents mutation in the oncogenes. Genistein also possesses antioxidant activity.

Limonene is found in essential oils of citrus fruits and spices. Limonene and one of its derivative known as Perillyl alcohol inhibit the growth of cancer. Limonene also enhances the process of detoxification in the liver.

Fibre protects the body against cancer by eliminating toxins from the digestive tract. Inositol hexaphosphate is found in the high fibre diet including legumes, cereals, grains, green vegetables and fruits, especially citrus fruit. Studies conducted by Fred Hutchinson Cancer Research Centre in Seattle, Washington have shown that inositol hexaphosphate possesses anticancer activity.

Lactobacilli, found in the human intestines, are friendly bacteria, which protect the body against cancer by detoxifying chemical carcinogens and by direct anticancer activity. Lactobacilli produce B vitamins, which enhance the immunity of the body. A study conducted on 138 patients of the bladder cancer has shown that there was a much lower incidence of recurrence of the bladder cancer after administration of Lactobacilli. Another study conducted on 100 patients suffering from advanced stages of cancer, has shown prolonged survival period and better quality of life after administration of Lactobacillus bulgaricus.

Selenium is a trace mineral, which is found in fruits and vegetables. Selenium is essential in the synthesis of an enzyme called glutathione, which plays an important role in detoxification process of the body. Selenium also enhances activity of the natural killer cells (NK cells) and arrests micrometastases. Selenium protects the body against cancer by stimulating the DNA repair enzymes. Data collected from 17 countries have shown that low intake of selenium in diet may lead to leukaemia and some other cancers including those of the colon, rectum, prostate, ovary, breast and the lung. A study done in Finland has shown that those persons, who have serum selenium levels below 45 mcg per litre, are three times more likely to develop cancer than those having the serum selenium levels above 45 mcg per litre. According to a report published in the 'Biological Trace Element Research' in 1991, the scientists at Chinese Academy of Medical Sciences Cancer Institute in Beijing have observed that incidence of the liver cancer was considerably lowered after administration of selenium in doses of 200 mcg daily for 2 years in members of those families who had a known family history of the liver cancer.

Copper is a trace element that plays an important role in functioning of the immune cells. Copper is an essential co-factor in the synthesis of an important group of enzymes, called cuproenzymes, which protect the body against cancer.

Zinc plays an important role in the synthesis of DNA. It protects the body against cancer, especially cancer of the prostate by enhancing activity of the immune cells. Zinc possesses antagonistic relationship with copper, i.e. the excess of one causes deficiency of the other. Zinc is found in onion, grains, soya bean and sunflower.

Germanium is a trace element that increases availability of oxygen to the cells. Germanium inhibits growth of cancer because the cancerous cells cannot survive under oxygen rich conditions. A study conducted on the inoperable cases of small-cell lung cancer, in Japan, has shown prolonged survival period and fewer side effects after administration of germanium along with chemotherapy and radiotherapy.

Molybdenum is a trace element that protects the body against cancer, especially the oesophageal cancer. Molybdenum detoxifies alcohols, aldehydes and sulphites, when given in very small doses of 150-500 mcg daily.

Chromium plays an important role in the synthesis of glucose tolerance factor (GTF). Chromium protects the body against cancer by regulating the blood sugar level and improving immune functions of the body. The prolonged consumption of refined food such as white sugar and white flour (which are extremely poor in chromium) may lead to hyperglycaemia that induces carcinogenesis by promoting synthesis of bad eicosanoid such as PGE-2.

Potassium protects the body against cancer by playing an important role in repairing the damaged DNA. A study conducted in China has revealed that high potassium and low sodium intake reverses the process of carcinogenesis.

Iodine protects against cancer, especially the breast cancer by playing an important role in repairing various tissues of the body. Iodine is required for proper metabolism and growth of the body. Iodised salt and seafood contain high contents of Iodine.

Manganese protects the body against cancer. Manganese is a co-factor in the synthesis of many enzymes, including the major antioxidant enzyme, called superoxide dismutase. Manganese also counteracts immunosuppressive effect of the stress hormone, cortisol.

Magnesium protects the body against cancer by playing an important role in the synthesis of DNA. Magnesium helps to maintain pH balance in the blood and other tissues of the body. Nuts, grains, brown rice and green vegetables contain high contents of Magnesium.

Calcium protects the body against cancer, especially the colon cancer. Calcium should be taken along with magnesium because it helps to absorb calcium. Nuts, dark green vegetables and milk contain high contents of calcium.