Feeding is an important pillar to an oncological process, as it can help reduce the side effects of the treatment and improve immunity. It has been shown that good nutrition is synonymous with higher quality of life compared to radiotherapy and chemotherapy treatments. Individual counseling is vital to avoid malnutrition, improve recovery and side effects such as nausea, vomiting, poor taste and alteration of smell among others. Studies show that 90% of the causative causes of cancer come from environmental factors and diet: diet, sedentary lifestyle, tobacco, environmental pollution, food poisoning like phytosanitary and additives, obesity, emotional and mental stress ... and a 5-10 Hereditary factors. Therefore, we have a large margin of maneuver to reduce these factors. • A first line is to consume organic foods, as they are free of phytosanitary, nitrates, glyphosates and other toxins by our body. • A second line is to reduce sugars, sweets and refined cereals to a minimum, such as wheat, rice, pasta, bread ... Substituting them for foods with a low blood glucose load such as whole grains (quinoa, buckwheat, rye, oats) but nevertheless it is important not to make the base of the food and if it is made from vegetables, especially green leafy and healthy fats, alkalizing and measuring the scale of the PH, trying not to be acidifying. It has been shown that a diet rich in sugars predisposes to cancer and also promotes its development, because hyperglycaemia activates oncogenes, decreases cellular vitality, increases preterm aging and strengthens stress by decreasing the neurotransmitters of the Well-being, it promotes the creation of new tumor cells, inflammation and therefore pain. Green leafy vegetables are important for their contribution of fiber, chlorophyll, folates that regenerate, provide cellular vitality and clean the toxins of the intestines. Also vegetable fats such as extra virgin olive oil, coconut oil, avocado, nuts, hemp seeds, squash pipes and xia. To avoid malnutrition, we also need protein and in this case, it is advisable to do it with quinoa, pulses, white fish, small blue fish, eggs and organic chicken. Not to mention the great need for vitamins and minerals we obtain from citrus fruits, raw nuts, hemp seeds, pumpkin seeds, sesame seeds, natural broths and algae. •A third line is to maintain immunity, and know that it depends on intestinal health and is compromised by fats, sugars, cold meats, dairy, alcohol, and gluten is dependent on cases. It is important to add an intestinal flora supplement to avoid problems of nutrient uptake and abdominal discomfort. We can help you with medicinal mushrooms (Xiitake, Maitake, Reishi), as they reduce the side effects and improve immunity and nutrition. • A fourth line is hydration, very important, as the taste can be altered by promoting dehydration. In these cases, try with cold infusions, water flavored with lemon peel and mint or ginger. Even add some raw honey or coconut sugar that has a low glycemic index. Due to some side effects, such as the metallic taste in the mouth, it is interesting to reduce the red meats, cold meats and pulses due to their iron content that increases taste. It would be important to value a Zinc supplement. If there is a feeling of dryness in the mouth or even warts are made Aloe vera juice can be a great help and an omega 3 supplement as well. Thus, the evidence that good nutrition against oncological treatment contributes an important increase in effectiveness, better recovery and better quality of life confirms a good reason for incorporating our diet as a treatment. You should always remember the importance of individualizing the nutritional treatment with a specialized professional.