Narrative Review about Importance of Nutrition on Survivors and in the Prevention of Cancer

Obesity is a public health problem in Brazil and around the world. Increased consumption of processed and ultra-processed foods has contributed to this epidemiological transition.8 9 It is a chronic disease with high inflammation of the tissues and it subsidizes several non-communicable chronic diseases such as diabetes mellitus, hypertension, coronary heart disease and cancer.8 9

Epidemiological data from 2016 estimate that 1.97 billion adults and 338 million children and adolescents are overweight and obese.10 Studies such as that of Kushi et al. (2006) reinforce that environmental factors, eating habits, lifestyle and obesity are more linked than hereditary factors.11 In addition, systematic reviews indicate that overweight and obesity are clearly associated with increased risk for the cancers: breast in postmenopausal, colorectal, endometrial, kidney, stomach, pancreas and gallbladder.11

In a combined analysis of the International Beacon Consortium study, the risk of cancer was estimated an increase of 1.54 times for people with BMI 25-29.99 kg/m2 ;12 double for individuals with BMI between 3034.9 kg/m² and five times for BMI = 40 kg/m², for oesophageal adenocarcinoma and oesophagogastric junction adenocarcinoma.11 12 13 Regarding to colon and rectum cancer, the interconnection is even more evident. Results of 60 studies and 86 control cases have demonstrated the positive relationship between increased body fat and cancer in this region.11 13

Neuhouser, Aragaki and Prentice (2015)14, a multicentric study on breast cancer and body composition, 67,142 American women, postmenopausal, between 50 and 79 years old were evaluated. In this article it has been suggested that obesity and overweight is a risk factor for breast cancer.14 Moreover, there was a strong association with Body Mass Index (BMI) above 35 kg/ m² (obesity II and III), with the risk of estrogen receptor-positive and progesterone receptor positive breast cancer, as well as, related to the increased risk for advanced stage disease.14 In a review of the American Institute for Cancer Research (2007), there is consensus from fifteen studies that BMI below 25 kg/m² is safe and healthy for disease control.7

Sedentary lifestyle is a very important risk factor for several diseases, mainly because it contributes to increase body mass.8 The World Cancer Research Fund estimates that 20% of all cancers diagnosed in the United States are related to physical inactivity, excess body fat, excessive consumption of alcohol, and poor diet.10

The American Institute for Cancer Research (2018) recommends for adults, performing at least 150 minutes of moderate physical exercise (walking, swimming, biking, dancing and gardening) per week or a minimum of 75 minutes of very intense exercise per week (intense aerobic, cycling and running).10 15 Physical activity is also relevant in patients during treatment.15 16 The controlled studies cited ₁₇ by Campia and Barac (2016), with women with breast cancer and children with leukemia,18 suggested that after about 12 weeks of physical exercise, there was an improvement in respiratory pattern and endothelial function during chemotherapy.16 17 18

In a multicenter and multinational study by Veldhoven et al. (2011), 778 individuals with non-Hodgkin's lymphoma and 690 with non-Hodgkin's cell lymphoma were recruited to correlate immune regulation and the reduction of the development of this disease.19 It has been suggested that there is no relationship between physical activity and the prevention or attenuation of lymphomas or any variation of this type.19 Physical activity it seems to prevent various types of cancer, however, its role is better elucidated in breast, colon, prostate and endometrial cancer.15 19

Several foods may increase or decrease cancer risk by stimulating or inhibiting genetic mutations.7 10 Therefore, food choices are critical in disease prevention.7 10 Therefore, the following will describe the main foods, highlighted by the literature, with potential activators or inhibitors of neoplasms.

Red Meat

The food habits of the majority of Brazilians are based on high consumption of red meat, mainly of bovine origin, due to the culture and great internal production in the southern region of the country.9

The American Cancer Society warns about the consumption of these foods.7 10 The recommendation should be limited to intake of lean, not charred, not processed, and until three or fewer servings per week.7 10 20 In addition, it suggests the substitution of red meat by chicken, turkey or fish in order to prevent colorectal cancer and others that are strongly evidenced in the literature by intake of red meat.7 10 20

The mechanism of induction to carcinogenesis in the ingestion of red meat is by stimulating the development of intestinal polyps, which can become malignant.20 In addition, red meats contain large amounts of heme iron, which in excess, causes intestinal cell toxicity.20 Evidence indicates that consuming 120 grams of red meat a day increases the risk of cancer by 1.2.21 About processed meat, the consumption of 30g per day increased the risk to 1.09.21 The Zandonai, Sonobe and Sawada (2012) study shows that ingestion of red meat is associated with increased risk for colorectal cancer by 28 to 35%.20 Processed meat is associated with increased risk by 20% to 49%.21 There are indications that each daily portion of 50 grams of processed meat increases the risk for cancer to 18%.22

The population study of Bellavia, Stilling and Wolk (2016), published in the American Society for Nutrition, and conducted with 74,645 Swedish men and women, suggests that high red meat consumption increased risk by 21% for several causes, including 29% for cardiovascular disease, but no increasing risk factors for mortality related to cancer.23 In addition, no direct relationship was found between the consumption of vegetables with red meat, in relation to cardiovascular disease and cancer.23

Recommendations of the José Alencar Gomes da Silva Cancer National Institute (2017)22 comprise: ingestion less than 300g of red meat per week and total exclusion of processed meat, such as turkey breast, salami, mortadella, ham, sausage, nuggets, and other ultraprocessed products.24 According to the American Institute for Cancer Research (2018) should limits the consumption of red meat to 3 servings per week (350-500g cooked, equivalent to 700750g raw meat) and also recommends the exclusion of processed meat.10

Fruits and vegetables are food of great variety, easily accessible and inexpensive, which are available throughout the year.13 According to the American Cancer Society (2012), the recommended consumption of these foods is at least five servings per day, preferably of varied fruits and vegetables.15 When consumed, we benefit from a large pool of vitamins, minerals and antioxidants.15 Fruits and vegetables are sources of soluble and not soluble fiber that help to reduce possible inflammation caused by increased of cholesterol, avoid coronary heart disease, reduce obesity and diabetes mellitus.25

Aghajanpour et al. (2017) study highlights inulin fiber for having been shown to reduce the biological production of compounds related to colorectal cancer.25 The anti-carcinogenic cellular mechanisms developed by these fibers include: cell proliferation, decreased exposure to genotoxicity, and decreased release of interleukin-2.25 Several epidemiological studies have shown that the consumption of fruits and vegetables reduces the incidence of oral cancer, tongue, esophagus, stomach and colon.26 The recommendation is a daily intake of raw fruits and vegetables.26 It is estimated that daily and varied consumption can reduce the risk for cancer by 60 to 70%.27

In Brazil, bean consumption is very common, unlike Eastern countries.9 Soy is a nourishment of the same group of beans, extremely rich in nutrients, and offer in abundance the isoflavone, a phytochemical with beneficial health effects.9 15 The recommendation is to consume one portion of soybeans per day (approximately 25 grams), in its “in natura” or minimally processed form as the grain, flour and tofu meal, because in the processing there is loss of 70% of isoflavone.28 This substance is classified as phytoestrogen, with structure and function similar to the natural estrogen, blocking the action of the hormone, due to competition for the same active sites of estrogen receptor.28 In addition, isoflavone inhibits the action of 17ß-hydroesteroid dehydrogenase, responsible for estrogen synthesis and induces serum steroid clearance.28

Messina et al. (2017) suggests that the relationship between soy consumption and breast cancer prevention is more effective when intake begins in childhood, since menarche in adolescence is associated with an increased risk of breast cancer.29 However, four studies have shown that soy intake in adolescence is still beneficial in reducing risk.29

In addition, the study by Baglia et al. (2016), conducted with 70,578 Chinese women aged 40-70 years, demonstrates that high soy consumption during adolescence and adulthood is associated with a significant reduction in the risk of premenopausal breast cancer.30 Ultimately, if consumption in adolescence is low and adulthood is high, there is still a benefit in preventing postmenopausal breast cancer.30

Ethanol is the type of alcohol found in many alcoholic beverages, such as beers, wines, liqueurs, distillates and others.31 32 Evidence shows that ethanol is responsible for a strong link with the development of cancer, independently of the type of alcoholic beverage.31 32 Alcohol acts by being harmful in several regions of the body. In the oral cavity and throat acts as a strong irritant, damaging the cells that come in contact, which in cell repair can lead to changes in DNA and mutations, inducing cancer of the mouth and esophagus.31 In the intestine, colon and rectum colonizing bacteria can convert large amounts of alcohol into the cancerous chemical called acetaldehyde.31 In addition, ethanol byproducts harm the liver, leading to inflammation and healing, inducing repair to damage and thus increasing susceptibility to DNA errors.31 32

Therefore, recommendations of a wine glass ingestion daily, because of the resveratrol benefits, should be made with caution, or preferably replaced by whole grape juice.33 According to American Institute for Cancer Research (2018), there is no safe amount for alcohol intake, the recommendation is not to consume.10 30

The study of Jayasekara et al. (2018) proves that lifetime alcohol intake and rates of survival are consistent and alcohol improves about 50% risk of colorectal cancer.34 However, correlating evidence with differential risks by anatomic location or by molecular subtype is not well established.34

Some “in natura” foods, in besides the function of nourishing, have particular components that are responsible for some metabolic and physiological actions.9 33 This therapy through the bioactive compounds of foods is called chemoprevention.33

The antioxidant, anti-inflammatory, anti-hormonal and anti-angiogenic capacity of some foods can act in the inhibition, delay or reversion of the carcinogenic process, by stimulating tumor apoptosis.33 Among these compounds are lycopene, isoflavone, catechins, resveratrol, gingerol, curcumin, and others. Below we show the main compounds, already elucidated, and proven by the literature (Table I).33 It is worth mentioning that food becomes functional if consumed along with a complete and healthy diet and on a regular and continuous basis.33

Source: SOUSA et al. (2017)33

In addition to the bioactive compounds mentioned above, there are other substances present in foods that play a similar mechanism of action, such as anthocyanins (present in grapes, cherries, strawberries, blackberries, apples, olives, figs, radishes, beans and eggplant); flavonoids and tannins (present in cocoa); and selenium (Brazil nut).33

Some vitamins also have this functional role, as is the case of beta-carotene that can be found in carrots, pumpkins, spinach, liver, mango, persimmon and beets, among others.30 All these components act in a beneficial way and behave as a prevention factor if consumed on a regular basis and in conjunction with a healthy lifestyle.33

Mode of preparation has a great influence on the nutritive value of the food. This phase requires a lot of attention, as doing so improperly may lead to nutritional losses in food and even to produce undesirable substances.35 Excessive fats in food preparation and frying are directly related to the formation of toxic products, which are potential carcinogens, such as acrolein and peroxides. In addition, by heating beyond the point of smoke or reusing oils, the chance of physical and chemical changes of this product increases, leading to the production of aldehydes, ketones, free radicals and trans fatty acids that are incorporated into foods and are extremely linked to cardiovascular disease, premature aging, arthritis, colon, breast and especially prostate cancer.3 35

Smoked food contains a number of polycyclic substances such as benzopyrene fluoranthene, chrysene and benzoaanthracene which are substances with carcinogenic power, especially for stomach cancer and large intestine.3 36 In addition, the study by Luzer (2017) complements the use of high temperatures to cook meat increases the concentrations of polycyclic aromatic hydrocarbons and other carcinogenic chemicals that may be related to breast cancer.36 The way of food conservation should also be taken into account, meat and fish that use salting as a conservation method, become potential carcinogens due to nitrosamines, especially nitrite and nitrate.37 These substances can also be found in large amounts in sausages and they are related to several types of tumors, especially gastric cancer.37 Dutra et al. (2007) shows a positive association between nasopharyngeal tumor and frequency of cured meats consumption, which contains high levels of nitrite.37

Survivors, individuals who overcome the cancer, need a special clinical look, because many of which are still debilitated and have different nutritional demands.10 11 They should maintain healthy eating habits with desirable weight and encouraged to have a physically active lifestyle, as well as encouraging other actions to avoid induction of erroneous cell mutations.6 8 38 In addition, maintaining a healthy lifestyle after treatment is directly linked to decrease in cancer recurrence, risk of presenting a second type of cancer and decrease of developing non-communicable chronic diseases.6 38 39

Arends et al. (2017) recommends, as a strong level of recommendation, that cancer survivors should maintain a BMI between 18.5 and 25 kg/m² and have a healthy lifestyle, including physical activity, vegetables-rich diet, fruits and whole grains, and avoid saturated fat, red meat and alcohol.39 These changes of habit would also lead to benefits for individuals with chronic diseases such as diabetes, osteoporosis and coronary heart disease, which cancer survivors are more likely to have than healthy individuals.39 The dietary recommendations for these individuals follow the same line of prevention; however, they sometimes require adaptation because they present transient or permanent sequelae due to the treatment performed.6 Depending on the site of the treated tumor, these sequelae may cause changes in taste, disorders in intestinal absorption, and inappetence.6

Shu et al. (2009) tested the administration of 11 grams of daily soy protein, and it was suggested an inverse association between soy consumption compared to recurrence and mortality by breast cancer.28

However, Arends et al. (2017) study addressed a range of studies concluded that vegetable and veggies based diet has no significant impact on reducing the risk of cancer recurrence. This same study suggests the relationship between elevated serum levels of carotenoids from food and decreased relapse of breast cancer.39

The study performed by Sierpina et al. (2015) brings the results of large observational studies, and points out that typical foods of the Western diet (red meat, fat, refined grains, excess sugar) are related to double the mortality and triple the cancer recurrence.26 Luzer (2017) evidenced high consumption of grilled or smoked meat to increased mortality due to breast cancer.36 Arends et al. (2017) complements that high consumption of pork, beef, mutton is related to colorectal cancer, breast and high mortality rate.39