[Etiopathogenic factors in colorectal cancer. Nutritional and life-style aspects. 2].

INTRODUCTION

Colorectal Cancer (CRC) is more prevalent in the countries that have an occidental type diet (rich in meat, animal fat, and refined carbohydrates and poor in fibre). Genetic differences among the various populations do not seem to be very important regarding this issue. Several geographic areas are suffering a growing rise in incidence that seems to be related to a greater local prosperity and a concomitant occidentalization of their diet.

NUTRITIONAL FACTORS

High fibre content in food has traditionally been considered as a protector factor against CRC because of multiple epidemiological studies; clinical trials have not been able to confirm it maybe due to methodological problems. Vegetables in general more than fruit, seem to have a certain protective effect, among the former, cruciferous vegetables and garlic should be highlighted. Red or processed meat seems to enhance risk, meanwhile it is not clear for white meat and fish seems to be protective. Ingestion of a high-calorie diet, overweight and the total contents of fat in diet seem to be related to a rise in the incidence of CRC; nowadays the possible protective effect of mono and polyunsaturated fatty acids (particularly the n-3) is starting to be considered. Among micronutrients calcium, vitamin D, folates, flavonoids, antioxidant vitamins (A, C and E) and selenium can be protective meanwhile iron may enhance risk.

STYLE OF LIFE FACTORS

Tobacco seems to be an important risk factor for CCRC even for those who use it moderately. Alcohol (specially liquors and beer) seems to be a direct risk factor also, in addition to its co-carcinogenic effect with tobacco. Physical exercise is increasingly been considered as a protective factor. Industrial workers who are in contact for many years with inorganic dust coming from plastic substances and fuel oil could have a greater risk of developing CRC.

CONCLUSIONS

A vegetable rich, red meat and fat poor diet seems to be ideal to avoid CRC. It is convenient to do exercise on a regular basis and to avoid overweight and the use of tobacco and alcohol. Protection against industrial waste substances is also important.