The consumption of fresh fruit and vegetables is preferable to industrial vitamin enriched food-stuffs, as they contain secondary substances extremely important in the prevention of certain diseases one being cancer. These secondary substances give colour and savour to fruit and vegetables. They react in symbiosis with one another for better efficiency.

Our metabolism, the transformation of food into energy, produces free radicals . These are molecules combined with oxygen, which lack an electron. Due to this lack, they search for equilibrium by combining with other atoms. Free radicals are able to attack the cellular membrane, break it down and attain the nucleus thereby provoking DNA mutations susceptible of causing cancer.

Free radicals are produced naturally by the body especially in diets rich in fat and sugar. They are also produced by the rays of the sun, pollution and cigarette smoke. Normally they are neutralised before they are able to damage cells. If this is not the case, the cells suffer with oxidative stress and the body must produce antioxidant substances to counteract free radicals.

In our organism vitamin C, E, beta-carotene, zinc and selenium are substances that neutralise free radicals. Secondary vegetal substances (aromats and dyes) are also antioxidants. For example: flavonoids in green tea, chlorophyll in broccoli, spinach and seaweed, anthocyane in eggplants, cherries, plums and other fruit. Sulfides in garlic and onions. Lycopene, the red colouring in tomatoes is a powerful antioxidant. Tomatoes are beneficial in all forms even in tins and tomato ketchup. Watermelons also contain high levels of lycopene.

Soya contains numerous antioxidant substances and is rich in calcium, magnesium, zinc and a number of vitamins belonging to the B group except B12. Soya contains high levels of phytooestrogen (vegetal oestrogen). These are isoflavone substances that the plant secretes to protect itself from stressful conditions. We think that these phytooestrogenes may protect the body from hormone dependant cancers such as breast cancer, endometrium cancer, ovarian cancer and cancer of the prostate. In breast cancer they react as does Tamoxifene on hormonal receptors as an antioestrogenic. They also prevent osteoporosis, cancer of the colon and cardiac diseases by reducing the levels of bad cholesterol (LDL).

Certain studies consider isoflavones as bad for the health when consumed in large quantities. Soya should be eaten moderately and in natural form. Concentrated chemical proteins should be avoided especially in the cases of pregnant women and families predisposed to hormone dependant cancers.

Colorectal cancer

For colorectal cancer, alimentation is of the first importance. A high consumption of saturated fat rich in calories combined with a lack of physical activity is a strong known risk factor. Alcohol, especially excess of beer should be avoided. It appears that high temperature cooking of meat produces free radicals favouring cancerogenesis. Saturated and mono saturated fat increases the concentration of biliary acid in the intestinal tract which may be implicated in colorectal cancerogenesis.

Alimentary fibres exercise a beneficial influence by accelerating the intestinal passage. One must however distinguish the difference between soluble and insoluble fibres. Insoluble fibres are not digested, for example, all cereals, whereas soluble fibres (pectin) found in fruit and vegetables play a protective role.

Chronic intestinal inflammation is an important high risk factor, as is hereditary predispositions. Metabolic problems modifies the quality of mucus produced by the mucosa, combined with environmental factors and inflammation can produce pre-cancerous modifications that would be well worth diagnosing as early as possible. Colorectal cancer often develops from polyps. The DNA contained in the cells must undergo many genetic mutations before producing a tumour capable of metastasizing. This may take 10 years. Colonoscopies and examination of the stools for blood are very important. We estimate that two thirds of all colorectal cancers are only diagnosed at the age of seventy.

Lung cancer

In Switzerland, lung cancer continued to increase in men during the 1980's to decrease back to its level of the 1970's. Unfortunately in woman the exact opposite has happened. Chemical elements contained in cigarette smoke (benzopyrenes) are able to transform certain basic gene oncosuppressors p53 and deactivate them. This deactivation prevents the bronchial cell from being able to remove alterations caused in its DNA.

Cigarettes are also responsible for cancer of the larynx, buccal cavity, pharynx, oesophagus and the bladder. They are also a co-factor in cancer of the kidney, uterine cervix, breast, stomach and leukemia. Cancerogenic agents are able to act synergically. A worker exposed to asbestos has a 10 times higher risk of suffering with lung cancer than others, however, if he is a smoker, he has a 90 times higher risk of developing the same tumour.

Melanoma

The frequency of malignant skin melanoma in Switzerland is lower than that of Norway and Sweden. Although it is a rare cancer, the increase is of 4% each year. This is a result of the abusive use of UV lamps and the increased exposure to the sun. Sunstroke suffered in childhood and adolescent years increases the risk of melanoma. The thinning of the ozone layer constitutes a high risk for the future.

Breast cancer

In the Occident, breast cancer is the most frequent cancer found in woman (except in the USA, it being lung cancer). In Switzerland, Holland and Great Britain are to be found the highest levels of breast cancer. The incidence is lower in Eastern and Southern Europe. The strong increase in the discovery of breast cancer these past years is most probably due to the better cancer campaigns (mammographies). Hormones are a very high factor however smoking appears to also play an important role in the increase of breast cancer.

There are a number of other factors that may play a role in the carcinogenesis of the mammary gland for example: precocious periods, late menopause, a first pregnancy at an advanced age, obesity which causes a poor metabolism of oestrogens and hormonal substitution at menopause for more than ten years. The presence of oestrogen and or progesteron receptors are a good prognostic to a beneficial response to anti-oestrogens (eg: Tamoxifen ). Higher the quantity more efficient is the response. Hormones also affect the cancerogenesis of the endometrium, the vagina, the thyroid and the prostate.

Prostate cancer

Cancer of the prostate is partly tied to the levels of testosterone. There are 3000 to 3500 new cases discovered each year with 1500 deaths. This cancer is the most frequent in men in Switzerland and Scandinavia. Due to better diagnostic methods we see an increase in the incidence of this cancer. Prostate cancer is often discovered during an operation for benign hyperplasia before it has manifested itself clinically. After a few years, the incidence also raises among migrants, which leads us to believe that environmental factors play a role in the etiology of this cancer. Heredity only plays a very small role, however the consumption of animal fat and a hormonal imbalance may cause this disease.

Uterine cancer

In Switzerland and most of the Occident a strong decrease in cervical cancer has been registered since the 1960's, due to better diagnostic methods. Unfortunately there are still a hundred deaths a year, two thirds over the age of 65. We now know that the carcinogenic process is set off with an infection of a HPV of oncogen origin (human papilloma virus). However other factors must come into play to enable further mutations to take place and develop a clone of tumour cells.

HPV virus belongs to the family which causes cutaneous warts and confines itself to the vulva, vagina and the cervix in woman and the penis in men. HPV is found in about 40% of women under the age of 20 but very rarely the lesions evolve into cancer. They do cause abnormal changes in the cells but these very often disappear on their own over a certain period of time. The virus may also lay dormant for many years only manifesting itself when the conditions are right. In men HPV hardly ever produces lesions.

We know that a number of factors can set off cancer: precocious sexual activity, many different partners, repeated infections which stimulates the process of regeneration with numerous mitosis, exogen hormonal stimulation (contraceptives) and tobacco. Condoms are a very efficient protection. Regular gynecological test even after the last pregnancy are extremely important in the prevention of lesions evolving into cancer.

Pour en savoir plus:

http://www.baclesse.fr/cours/fondamentale/c16-hormonoth/Hormono-0.htm hormones et cancer

http://www.ibreast.org/rcr_metas_HrmThr.html hormonal (Anti-Estrogen) Therapy

http://www.aafp.org/afp/20000315/1759.html colorectal cancer

http://soyfoods.com/nutrition/SoyIsoflavonesGrowth.html propriétés des isoflavones

http://www.aerztezeitung.de/docs/1999/12/06/222a1502.asp le soja et le cancer de la prostate (Deutsch)

http://www.indomedia.com/intisari/1999/oktober/terapi.htm les aliments antioxydants et le cancer (bahasa Indonesia)