Cancers are multifactorial diseases whose determinism is influenced by individual factors (age, genetic predisposition) and others related to the environment: smoking, alcohol consumption, dietary habits, nature of food and risk exposure (infections, toxic products).
The share of the diet responsible for the appearance of cancers is around 30%, although it is difficult to establish causal relationships, with certain exceptions. In this regard, during cancer treatment, it may be necessary for the patient to change his or her diet. This may involve eating certain foods that would not normally be recommended in optimal health.
To improve the quality of life and prognosis, a nutritional diagnosis and a specific dietary approach will be made. It is important to note that the impact of diet on carcinogenesis is uneven and potentially involved in all stages of carcinogenesis.
Diet, obesity and cancer
Nutritional status, food and cooking methods can be detrimental or protective to health.
In this sense, overweight and obesity increase the risk of some cancers and also the risks of relapse and mortality.
In turn, obesity increases the risk of pre- and post-surgical complications and weight gain, in certain tumors such as cancer and breast cancer, is associated with a worse prognosis.
A balanced diet and the practice of regular exercise can prevent cancer in people in good health and avoid relapses in patients who have suffered from it.
Recommendations
Balanced diet:
- Proteins: it is recommended to include protein-rich foods such as lean meats, fish, eggs, legumes, tofu, and low-fat dairy products.
- Complex carbohydrates: whole-grain carbohydrates such as oatmeal, brown rice, and whole-grain bread, which provide sustained energy, should be prioritized.
- Healthy fats: it is advisable to opt for healthy fats such as nuts, avocado, olive oil, and oily fish (omega-3).
- Vitamins and minerals: fruits and vegetables rich in antioxidants (vitamin C, E, and carotenoids) help fight cell damage.
- Hydration: staying well hydrated is crucial, especially if treatments cause side effects such as vomiting or diarrhea. Water, broths or caffeine-free infusions are recommended.
What foods can help control the side effects of treatments?
- Nausea: eating small, frequent meals and avoiding fatty or spicy foods may help.
- Loss of appetite: eat small portions, high-calorie and high-protein foods, and use liquid nutritional supplements if necessary.
- Mucositis (inflammation in the mouth): avoid acidic or spicy foods, and opt for soft and warm textures.
Harmful foods
Fatty and fried foods. These are difficult to digest and may cause discomfort, nausea or diarrhea. Fried foods, fast foods, and products high in saturated or trans fat should be limited.
Processed and ultra-processed foods. Processed foods are foods that receive industrial processing during which the nature of the original food is changed by adding fat, salt, sugar, additives, or other components. Ultra-processed foods are highly processed foods, which are mostly made from industrial ingredients and in which natural foods are unrecognizable or present in very small quantities.
Fats. Fat consumption in menopausal women is related to the development of cancer due to increased estrogen production. The reduction of fat consumption by 15% reduces the relapse of breast cancer.
Red and processed meats. Products such as sausages, bacon, sausages and cured meats have been associated with an increased risk of cancer, especially digestive, and can irritate the digestive system. The practice of certain culinary procedures such as pyro-synthesis during smoking, grilling or roasting produces polycyclic aromatic hydrocarbons (PAHs) and amines, which are potentially carcinogenic. It is recommended not to consume the carbonized parts.
Insoluble fiber. Although fiber is important, in cancers affecting the intestine or colon, too much insoluble fiber (such as that present in bran, seeds, and some raw vegetables) can cause discomfort, bloating or diarrhea.
Refined sugars. Sweets, cakes, soft drinks and other foods with high levels of sugar can contribute to inflammation and metabolic imbalances. It is better to opt for natural sources of sugar such as fruits in moderate portions.
Spicy or highly seasoned foods. They can irritate the digestive tract and worsen symptoms such as heartburn, reflux, or abdominal pain, especially in people with esophageal or stomach cancer.
Full-fat dairy. High-fat dairy products can be difficult to digest and worsen digestive symptoms. Low-fat versions or plant-based alternatives may be preferred.
Caffeinated and carbonated beverages. Coffee, black tea, energy drinks and carbonated soft drinks can irritate the stomach and increase reflux problems. In addition, carbonated beverages can cause bloating.
Alcohol. Alcohol can irritate the digestive tract and weaken the immune system. It is associated with aero digestive tumors (VADs), as well as hepatocarcinoma. In digestive cancers, even in small amounts, it can aggravate symptoms or interfere with treatments.
Raw or undercooked foods. In patients immunosuppressed due to cancer treatments, it is crucial to avoid raw or undercooked meats, seafood and eggs, as they can increase the risk of infections.
The key is to individualize the diet according to the patient’s symptoms and needs, always with the support of a specialized medical team or nutritionist.
Beneficial foods:
Fish: consumption of white fish (such as hake or sole) is associated with a decreased risk of colon cancer.
Easily digestible proteins: it is essential to include light protein sources such as:
- Turkey or chicken: skinless and steamed or grilled.
- Eggs: particularly egg whites, which are rich in protein and softer for the stomach.
- Soft legumes: such as lentils or chickpeas, cooked and pureed if necessary, to facilitate digestion.
Complex and soft carbohydrates: refined cereals and products rich in soluble fiber are well tolerated.
- Oatmeal: Rich in soluble fiber, it aids digestion and is gentle on the digestive tract.
- Cooked white or brown rice: According to the patient’s tolerance.
- Potatoes and sweet potatoes: boiled or steamed, they are easy to digest and provide complex carbohydrates.
Fruits with low content of insoluble fiber: some fruits can be better tolerated cooked or without peel. It exerts a protective factor by reducing oxidative stress, and by the protective effect of microconstituents such as carotenoids. Recommended:
- Peeled or cooked apples and pears.
- Ripe banana: Rich in potassium and easy to digest.
- Papaya: Contains enzymes that promote digestion and is gentle on the stomach.
Cooked and soft vegetables: opt for steamed or boiled vegetables.
- Carrots, zucchini, spinach and pumpkin: Cooked, they are a rich source of nutrients and soluble fiber, but softer for the digestive system.
- Broccoli and cauliflower: in small quantities and well cooked, although some people can avoid them if they generate gases.
Healthy fats: although they should be consumed in moderation, healthy fats are important.
- Extra virgin olive oil: Easy to digest and with anti-inflammatory properties.
- Avocado: Source of healthy fats and energy.
Foods rich in antioxidants: Antioxidants help fight oxidative stress and protect cells.
- Red fruits (such as blueberries and blackberries), if they are well tolerated.
- Carrots and pumpkin: rich in beta-carotene, which are antioxidants.
Soft and nutritious liquids: maintaining good hydration is key.
- Bone broth: nutritious and easy to digest, it also provides collagen.
- Herbal teas such as ginger or chamomile, which can help soothe the digestive system.
- Smoothies or purees: made with light, nutrient-rich ingredients, especially if there is difficulty chewing or swallowing.
Probiotics and mild prebiotics: help maintain intestinal health, but should be introduced under medical supervision.
- Plain yogurt: rich in probiotics, but should be low in fat and without added sugars.
- Kefir: Similar to yogurt, it can be useful if the patient tolerates it well.
Ginger: known for its properties to relieve nausea and improve digestion, especially in those undergoing chemotherapy.
It is essential that food be prepared simply (steamed, boiled, grilled) in order to facilitate digestion and avoid the production of polycyclic aromatic hydrocarbons and amines, potentially carcinogenic.
Specific recommendations according to the type of tumor.
The diet should be personalized according to the patient’s symptoms and type of cancer. The diet should always be optimally adjusted and take into account that there are some variants according to the cancer considered:
Breast cancer
- It correlates with alcohol consumption, excess calories and weight overload.
- Consumption of vegetables reduces it.
Colorectal cancer
- It is correlated with a diet rich in red meat, refined cereals, alcohol consumption, as well as insufficient fiber intake.
- The practice of regular physical activity and low-energy diet could reduce the incidence of this type of cancer by 50%.
Gastric cancer
- It is related to Helicobacter pylori infection. A diet that is too salty and rich in salted and smoked foods can favor the persistence of this infection.
Lung cancer
- A diet rich in fruits and vegetables can reduce the incidence by up to 30%.
These considerations only make sense in the context of a balanced diet; phytoestrogens, milk and calcium can have a beneficial effect, and at the same time a detrimental effect if consumed in excess. A vitamin D effect, could have a detrimental effect.
Recommendation for cancer prevention
It is advised:
- Consumption of fruits and vegetables up to about 400 gm/day, within a diversified diet.
- Consumption of proteins in the form of white meat, fish, poultry and eggs.
- A diet rich in fiber
- Store products in refrigerator or freezer to avoid microbial contamination; discard perishable products, susceptible to contamination with fungi; in both situations nitrosamines are produced, implicated in carcinogenesis.
- Cook food at moderate temperatures.
- Maintain an adequate BMI from infancy, avoiding foods with a high energy load.
- Breastfeeding is associated with a lower incidence of breast cancer.
- Regular physical activity before, during and after treatment, improves quality of life, reduces the feeling of fatigue, reduces the overall mortality rate and the recurrence rate.
It is not recommended:
- Alcohol consumption.
- Excessive consumption of red meat: <300 mg/week. Avoid barbecue or direct flame cooking.
- Reduce consumption of fatty or very salty deli products.
- Consumption of salt or very salty foods such as salted or smoked foods.
- Cooking over a flame or grill
Cancer predisposes to a risk of malnutrition which reduces the defenses and quality of life of cancer patients. The nutritional approach to cancer patients should be integrated into the specific treatment program. The state of health depends on maintaining the correct level of nutritional intake to avoid malnutrition. Patients with adequate nutrition have better tolerance to treatments such as chemotherapy and radiotherapy.
Adequate nutrition is crucial to avoid loss of muscle mass and function (known as sarcopenia). Optimal nutritional status improves the patient’s response to treatment and quality of life. Malnutrition weakens the immune system, which increases susceptibility to infection and complicates wound healing and tissue repair. Immunomodulatory formulations used in patients with gastrointestinal tumors have been shown to be effective not only in improving nutrition but also in strengthening the patient’s immune system.
Food and weight monitoring is important for any type of treatment.
The diet must be sufficient and varied, avoiding those foods that are harmful both in the predisposition to develop the disease and to favor relapses of the same.
At IVOQA we have a nutritional prehabilitation service. This is a preventive and proactive approach that focuses on improving the nutritional status of patients diagnosed with cancer before starting cancer treatment. This approach is essential, since a high percentage of cancer patients present malnutrition at the time of diagnosis.
