**Abstract**

The antioxidants are molecules capable of retarding or anticipating the oxidation of other molecules. Epidemiological results have shown that the persons who consume a rich diet of fruits and vegetables present a minor risk of suffering different types of cancer, cardiovascular and neurological diseases, and a minor mortality than the persons who consume few fruits and vegetables. Others studies suggests that the vitamins are antioxidants like can to decrease hurt oxidative in the physiopathology of many chronic diseases and cancer.

Nevertheless, evidence of new studies in mice shows that vitamins can promote the growth of tumors and metastasis and the expression of the gene p53. Current studies indicate that patients with cancer and people who have a major risk of cancer will have to avoid taking complements of antioxidants, due to the fact that it was thought that antioxidants might protect cells against cancer since they neutralize reactive oxygen species (ROS) that can damage the DNA, but in studies of animals, it has been indicated that the presence of major concentrations of antirust exogenous prevents the type of hurt of free radical that has been associated with the formation of cancer.

**Keywords:** nutrition, antioxidants, treatment, cancer, diseases

### **1. Introduction**

Antioxidants are molecules that act disabling the reactions of oxidation in chain that they produce cellular hurt withdrawing radical free and disabling other reactions of oxidation.

Production of free radicals is regulated by different metabolic routes, and they are considered as the first line of defense in the human body.

Currently, consumption of foods rich in antioxidants such as functional foods as omega-3 and glutamine [1] plays an important role in the nutrition of the population. As functional foods that contain fiber, vitamins, minerals and which decrease saturated fats or sugars are considered [2].

The advantages of the consumption of antioxidants have been reported, but currently a research has discovered the disadvantages in their consumption; for example, vitamin A and N-acetyl-cysteine dosed to mice induced with lung cancer increase the size of the tumors, and these substances can eliminate the expression of the gene *p53* (suppressing gene of tumors) activated when hurt exists in the DNA [3].

On the other hand, a functional food is according to the ESPEN guidelines a "food fortified with additional ingredients or with nutrients or compounds intended to yield specific beneficial health effects." Functional foods can be prepared with vitamins and minerals or other compounds of nutritional or physiological effects, and their dose form can be different [4].

In Europe and USA the consumption of dietetic supplements more commonly are antirust vitamins and mineral supplements.

This paper explains the importance of the consumption of antioxidants in the human nutrition and in patients with cancer, who have been treated with chemotherapy and radiotherapy, and their use to other diseases has been mentioned.
