Cancer Incidence and Mortality in Different Countries with Special Reference to Dietary Practices - Research Paper Example

Environmental Factors and Cancer Incidence and Mortality in Different Countries, With Special Reference to Dietary Practices ABSTRACT It is a well known fact that nutrition plays a major role in prevention of cancer together with other lifestyle changes and physical activity. Researchers support the plant based diet to be the best for the prevention as well as in those survivors of cancer. A variety of fruits and vegetables need to be added to once diet and it is good to select these fruits and vegetables based on different color. Different phytonutrients are present in fruits and vegetable with different color and a variety based on this criterion would be easy for identification by a layman. A diet that has high fiber food such as whole wheat, a balanced ratio of omega 3 and omega 6 fats, antioxidants and phytonutrients from fruits and vegetables, such as α & β-carotene, β-cryptoxanthin, vitamin C, vitamin E, selenium, and other nutrients can aid in prevention of different types of cancers. This paper focuses on the role of nutrition in prevention of cancer and recurrence in those undergoing treatment for cancer. Introduction Cancer has always been a dreaded disease that I have ever come across in my life. There are many who have cancer and unfortunately, in many cases, it is because of ignoring some of the basic aspects of life such as good nutrition. I have seen people suffer and die of this disease. My grandfather died of bone cancer and my mother has had thyroid cancer. Today, though there are easy methods of detecting and good treatments available, I believe that it is better to prevent cancer rather than look for treatments after having it. Over the years I have been keen to find natural methods to prevent cancer and nutrition is one of the prime subjects that I have come across. This paper highlights the importance of balanced nutrition in preventing cancer and also looks into the role of balanced nutrition in the recovery phase among the survivors of cancer. Hippocrates (460-377 BC) stated that “….let food be your medicine and medicine be your food”. Today, after several centuries I would like to believe that what goes into the body as food mainly determines the health of a person. Though environment and other exposures may be reasons for a disease, a healthy person will be able to withstand adverse circumstances. Therefore, if nutrition has to take care of us, then what kind of nutrition is best for preventing diseases such as cancer? Researchers suggest that a plant based diet that includes fruits, vegetables, whole grains and legumes are the best for cancer prevention (Mahtani, 2010a, para. 1). It is estimated that about one third of all cancers are due to poor nutrition. The use of tobacco is another major reason for additional one third cancers and if these two factors are controlled many people can be protected from this dreaded disease. Understanding the basic fact that a healthy diet plan together with regular exercise, a check on the body weight and avoiding tobacco and alcohol are some of the most simple techniques to keep one healthy and free from cancer or at least lower the risk of cancer. A plant based diet is rich in chemicals known as phytonutrients. These are healthy nutrients that are very essential for the well being of individuals. Phytonutrients include vitamins, minerals, and other chemicals such as antioxidants necessary for the prevention of cancer. Researchers suggest that the intake of phytonutrients is directly linked with the prevention of cancer. It is important to consume variety of fruits and vegetables rather than the same set of fruits and vegetables on a day-to-day basis. This gives us the benefit of a variety of plant based nutrients maximizing the cancer fighting agents in the body (Mahtani, 2010a). Another important question to be answered is that how will nutrition help cancer survivors? Though there are many researchers who have studied the role of nutrition in prevention of cancers, very less research has gone into role of nutrition for cancer survivors. Today, there are an increasing number of researchers who are contributing to this knowledge and have suggested that nutrition plays important role in prevention of the recurrence of cancer. Further, the studies suggest that the same diets that cut down the cancer risk may reduce risk of recurrence in cancer survivors. Which mean to say that a plant based diet rich in a variety of phytonutrients is among the top foods that need to be consumed. It is also important to cut down on saturated fat and highly processed vegetable fats that can add on to the free radical damage. In addition to fruits and vegetable, it is also important to eat whole grains that contain lot of cancer fighting nutrients. The fibers present in this category of food are helpful in reducing the cancer risks by maintaining normal body weight (Mahtani, 2010b). Coloring Our Diet: Reduces Cancer Risks Studies have revealed the importance of colors in the diet. These natural colors provide a variety of antioxidants for cancer fighting. For example, the antioxidants that are present in red tomatoes are mostly similar to that found in other red fruits such as watermelon or pink grapefruit. Though it may not be a highly perfect system to identify and categorize antioxidants based on colors, it is an easy method to explain its importance to layman to differentiate antioxidants in a simple way and add variety to the diet. Red color: Lycopene is the well known antioxidant present in tomatoes, pink grapefruit, guavas with pink flesh, Japanese persimmon, watermelon and red cabbage. This is an important antioxidant that helps in fighting cancer causing agents especially in the case of prostate cancer. According to population-based studies on people with advanced stages of prostate cancer clearly demonstrated increased blood levels of lycopene and better intake of fruits and vegetable with lycopene reduced risk prostate cancer. Nowadays, the early detection of prostate cancer has helped the individuals to make adequate changes in diet pattern and as a result not many long term studies are available. However there are several short term studies that give enough evidence that lycopene from natural sources or from supplementation, can be of great help to prevent prostate cancer as well as help the survivors of prostate cancer. Additionally, several animal studies also have demonstrated the capability of lycopene to diminish tumor growth. Therefore, if lycopene can prevent us from cancers, it would be a good idea to include cooked tomatoes, juices, pasta sauce, soups and ketchups in our daily diet (Heber, et al. 2009). Red/purple group: Most of the fruits in this group are known to contain anthocyanins that are responsible for the color of the fruit. The fruits such as pomegranates, grapes, plums, and assorted berries all fall into this category. Additionally each of these fruits and berries are known for their unique benefits and different properties. For example, pomegranates have a unique chemical ellagitannins that is anti-inflammatory in nature. These are known to benefit people with high risk of heart disease, cancer prevention and dementia. Cranberries have proanthocyanidins that prevent bacterial infection in the urinary tract. Further, researchers are still working on fruits such as blackberries, strawberries, and raspberries for there benefits in addition to their unique are antioxidant nature (Heber, et al. 2009). The orange group: These are group of fruits and vegetables that are rich in alpha and beta carotenes. The examples include carrots, mangoes, apricots, cantaloupes, pumpkin, and sweet potatoes. Beta-carotene is converted to vitamin A in the body and is very essential for vision. Additionally it works synergistically when combined with the red, green, and yellow/green antioxidants. It is estimated that for an average American diet, carrots provide almost 50 % of the alpha and beta carotene (Heber, et al. 2009). The orange/yellow group: The main fruits that come in this category include oranges, peaches, papaya, and nectarines. These are known to contain betacryptoxanthin and also minor carotenoid. In an average American it is estimated that approximately 87% of cryptoxanthin comes from orange juice, oranges, and tangerines. Though fresh fruit juices are a good source of antioxidants, the processed juices lack the nutrients and fibers and contain high sugars (Heber, et al. 2009). The yellow/green group: This group is the providers of lutein and zeaxanthin and these are present in spinach, collard, yellow corn, green peas, avocado, and honeydew melon. These carotenoids are mainly involved in the health of eyes. Any deficiency of these may lead to cataracts and age-related macular degeneration (Heber, et al. 2009). The green group: This includes all green leafy vegetables especially broccoli, Brussels sprouts, cabbage, bok choy, and kale. The main antioxidants in this group are sulforaphane, isothiocyanates, and indoles and their main function is to stimulate genes in the liver to produce enzymes that break down carcinogens. Hence, this is one of the major nutrients that are essential in preventing cancer (Heber, et al. 2009). The white/green group: These have the major role in activation of antioxidants in the body and contain allyl sulfides. Garlic, onions, asparagus, leeks, shallots, and chives are included in this group (Heber, et al. 2009). The research continues to explore the unbound potential of plant based foods. There are still several unique benefits that are present in each fruit and vegetable that is yet to be identified. Besides the plant foods that are not included in the above mentioned coloring system such as celery, mushrooms, etc have unique benefits. Further, the importance of fresh fruits and vegetables should not be ignored. For instance, fresh tomatoes from the farm have deeper color and have high amounts of lycopene when compared to the regular store bought tomatoes. Therefore, it is essential to keep in mind freshness, color and variety of fruits and vegetables to maximize the benefits of phytonutrients required to maintain healthy tissues and reduce the risk of diseases particularly cancer (Heber, et al. 2009). Fruits and vegetables in the diet can add several anti-inflammatory and antioxidant substances that are literally nil in processed foods that depend on sugar, salt, and fat for flavor. Therefore, if each one of us focuses on healthy diet with plenty of fresh fruits and vegetables, fish, and whole grains, it can bring done the number of cancers and other diseases. Consumption beverages such as juice of pomegranate, apple, oranges and green and black tea can increase levels of antioxidant. The vegetables belonging to the cruciferous group, such as broccoli, Brussels sprouts and horseradish provide us with beneficial substances that helpful for the liver and tissues in addition to their antioxidant property. The USDA conducted research in several fruits and vegetables and concluded the following to be the only top 20 natural foods that are rich in antioxidants: “small red beans, wild blueberries, red kidney beans, pinto beans, cultivated blueberries, cranberries, artichokes, blackberries, prunes, raspberries, strawberries, red delicious apples, Granny Smith apples, Pecans, sweet cherries, black plums, russet potatoes, black beans, plums, gala apples” (“What are antioxidants, free radicals and flavonoids”, 2008; “Strawberries Among Super Foods For Super Health”, 2006). Camellia sinensis (the tea plant) is another source of rich antioxidants. The practice of drinking tea to preserve excellent wellbeing among human beings dates back to centuries. For instance, there are literatures saying that the early Buddhist and Chinese healing practices included the herb Camellia sinensis. Cancer is the result of free radical damage of the cells. When there is an exposure to carcinogenic substances, free radicals are formed in the body that sets in a chain of reaction that damages the cells and tissues of the body and causes cancer. In other words, the free radicals damage the cells in such a way that their normal functioning is hampered. One of the most common ways to control the free radical formation and stop its damaging chain reaction is by the action of antioxidants. Several studies have shown that tea has high amounts of antioxidants that can prevent cancer. The principal polyphenols in green tea― epigallocatechin-3-gallate (EGCG), Epigallocatechin (EGC), Epicatechin-3-gallate (ECG), and Epicatechin (EC)―and the theaflavins and thearubigins in black teas comprise antioxidant activity. These chemicals, mainly EGCG and ECG, contain considerable free radical scavenging action and possibly will defend cells from DNA damage (Henning et al., 2004). Laboratory studies provide enough evidence on the action of tea polyphenols in hindering tumor cell propagation. It also induces apoptosis in laboratory and animal studies. There are also studies that point out the inhibition of angiogenesis and tumor cell invasiveness by the catechins present in tea. The polyphenols also have a protective action from the damaging UVB radiation (Lambert and Yang, 2003) and are known to adjust immune system function. This study also finds that green tea activates detoxification enzymes such as glutathione S-transferase and quinone reductase. As a result give good protection against tumor development (Steele et al., 2000). Though there are several animal studies that show the cancer prevention effects of polyphenols, not many human studies have been carried out. In animal studies these polyphenols have been found to inhibit tumorigenesis in different tissues and organs such as skin, lungs, oral cavity, stomach, intestine, liver, pancreas and mammary glands. A few epidemiologic studies on the impact of tea in reducing cancer risks are published in the recent years. The results point out that there is an association between tea consumption and cancer risk reduction especially the cancers of the colon, breast, ovary, prostate, and lung (Sun et al., 2010; Simons et al., 2007). However, there is a great variation in results of these studies. This conflicting results may be owing to variables such as diversities in the method of preparation and consumption, the types of tea used for analysis, cultivation methods and variation in genetic variety, the amount of tea consumed etc. There are several population studies around the world that have linked the risk of cancer with that of the dietary pattern. For instance, in the developed western world the diet include animal products, fat and sugar and these were linked to the high rates of cancers of the colorectum, breast and prostate. On the contrary, in developing countries such as India and China the diet is based on one or two starchy staple foods such as rice or wheat, however the lower intakes of animal products, fat and sugar cuts down the risk of western cancers but other types of cancer such as cancers of the oesophagus, stomach and liver are high in these regions (Armstrong and Doll, 1975). It is also studied that migration has an influence on the occurrence of certain cancers. For example, earlier Japanese people were having low rates of colorectal cancer. But among those that migrated to US in recent years and those who are exclusively dependent on westernized diet, there is an increase in colorectal cancer (IARC, 1990). Therefore, it can be said that with the international variations in diet and its link with cancer rates, if people opt for healthy diet, they can surely prevent cancer. Westernization includes numerous changes in diet and lifestyle, and is not just the increased intake of meat, dairy products, sugar and other refined carbohydrates, proteins and fats. The fast food culture is increasing with westernization. This kind of diet is high in fat content and is abundance of macronutrients. With respect to the nutrients intake it can be said that Western diets are characterized by sufficient or too much energy intake, together with soaring intakes of protein and fat, but micronutrient absence (vitamins and minerals) is a lot more widespread in developing countries (Key et.al., 2004). Nutrition and Types of Cancers Cancers of the oral cavity, pharynx and oesophagus: It is estimated that oesophageal cancer very common in both developed and developing countries such as parts of Central Asia, China and Southern Africa than in most parts of Europe, North America and West Africa. In developed countries, while alcohol and tobacco contributes for majority of this kind of cancers, in developing countries, it is the deficiency of micronutrients from the fruits and vegetables that contributes for these cancers. Though the comparative roles of different micronutrients are yet to be established, studies point out that deficiencies of riboflavin, folate, vitamin C and zinc may be mainly responsible (Key et.al., 2004). Nasopharyngeal cancer: it is estimated that there is a high incidence of this cancer especially among children. It is most commonly seen in parts Southeast Asia and is linked with high intake of Chinese style salted fish (Key et.al., 2004). Stomach cancer: It is only 2 to 3 decades that the number of cases of stomach cancer has come down until then, this was one of the most common reason fro death. Though one of the main risks identified for stomach cancer is the bacterial infection caused by H. pylori 25, diet is one of the important factors in the etiology of stomach cancer. It is linked with high intake of salty and spicy food which is common in Asia than in Europe or North America. According to studies in Linxian, China, it was found that supplementation with b-carotene, selenium and a-tocopherol resulted in a considerable reduction in stomach cancer mortality. However the study could not find significant benefit from vitamin C (Key et.al., 2004). Colorectal cancer: Researchers have found that the incidence rates of colorectal cancer are approximately ten times more in developed when compared to developing countries. Further obesity and overweight is considered a major cause for this type of cancer. In fact more than 75 percent is diet related factors that are responsible for colorectal cancer. It is also suggested that some aspects of a Western diet are a major determinant of risk. For instance, studies suggest that the cooking of meat at high temperatures result in formation of mutagenic heterocyclic amines and polycyclic aromatic hydrocarbons and additionally nitrites and their associated compounds that are found in smoked, salted and some processed meat products may be transformed to carcinogenic N-nitroso compounds in the colon. According to another study by Burkitt (1969) it was found that in Africa the colorectal cancer is low and further investigation found that they consume high amount of dietary fiber. Fiber enhances stool bulk as a result of which it speeds the transit of food through the colon thereby reducing the uptake of carcinogens by the colonic mucosa (Key et.al., 2004). Cancer of the liver: Liver is one of the vital organs in the human body and it is estimated that about 75 percent of cases of liver cancer occur in developing countries especially in the sub-Saharan Africa and Southeast Asia than in Europe and North America. Though not dietary, one of the major risk factor involved in liver cancer is chronic infection with hepatitis B. Additionally the intake of contaminated foods with mycotoxin aflatoxin is an important risk factor in developing countries with active hepatitis virus infection. In the developed countries and to some extend in developing countries, excessive alcohol consumption may also result in liver cancer in a longer run (Key et.al., 2004). Cancer of the pancreas: This type of cancer is more common in Western countries than in developing countries. One of the major diet related risk is the increasing obesity and overweight in the western countries. Researchers suggest that an increase in plant based diet and simultaneous decrease in animal based diet can reduce the incidences of cancer of pancreas. Lung cancer: Though the major reason for lung cancer is linked with smoking, deficiency of micronutrients, antioxidants and plant based diet is linked with lung cancer. Smoking introduces several millions of free radicals in the body that damages the lungs. Cancers in Women: Cancers such as breast cancers, endometrial cancer, cervical cancer and cancers of ovary is common both in developed and developing nations. There are several reasons and risk factors that are linked to these cancers. Dietary deficiencies especially the micronutrients and antioxidants together with lack of physical activity are among the top reasons for these cancers. For instance, studies have shown that obesity in the reason for increase in breast cancer risk especially in postmenopausal women possibly by escalating serum concentrations of free oestradiol. Additionally, alcohol is another well studied and established dietary risk factor for breast cancer. In the case of endometrial cancer risk it is about three times higher in obese women when compared to women with normal weight. Here again the incidence is higher among the postmenopausal women due to the hormonal changes (Key et.al., 2004). Prostate cancer: Prostate cancer incidence rates are about 10-folds high in North America and Europe when compared to Asia. Though researches are still on to find more about the etiology of prostate cancer, some studies suggest that it may be positively associated with Westernized diet. For instance, red meat, dairy products and animal fat have been linked to development of prostate cancer. Studies also suggest that supplements such as vitamin E89 and selenium90 might have a protective effect for prostate cancer. Lycopene from tomatoes, as discussed earlier also reduce the risk of prostate cancer (Key et.al., 2004). Other cancers: There are several types of cancers that can affect kidney, bladder, blood, thyroid, lymph nodes, bone marrow and several other parts of the body. Though recent studies are able to point out several factors that may be responsible for the etiology, a healthy diet with balanced macro and micronutrients along with good amount of antioxidants can help in the prevention of these cancers. Certain times there are unavoidable environmental factors that may be a reason for release of carcinogens, but the bodies self defense mechanism will be able to protect the individual to some extend if they get good nutrition (Key et.al., 2004). Conclusion Numerous sources of carcinogens directly or indirectly causes or leads to more destructive forms of cancer and the definite mechanism and the cellular changes is still under study. Today it is difficult to avoid all exposure to carcinogens. However there are some of the controllable factors such as good exercise, healthy diet and healthy eating practices, adequate rest can avoid or nullify the impact of these chemicals in the body. The food that we eat need to be healthy and nutritious. Plant based diet with a variety of fruits and vegetables can help in prevention of cancer and also those survivors of cancers. Reducing the diet based on animals can also help to avoid the increase of carcinogens in the body. Further, overcooking of any type of meat, especially the red meat at very high temperatures results in the production of toxic carcinogens called heterocyclic amines. According to an animal based study one of the heterocyclic amines known as PhIP is linked with the development of prostate cancer. It is also known that charbroiling red meat or chicken along with its skin releases carcinogens called polycyclic aromatic hydrocarbons that can cause cancer. In addition to nutrition, regular exercise helps in releasing the antioxidants that are naturally present in the body. Exercises are helpful in burning calories, especially in those people who are over weight and obese. Endurance form exercises that include walking, running, cycling, and swimming are mainly involved in increasing the body’s own stock of antioxidants that are necessary to remove inflammatory molecules that drive cancer. There are studies that point out that about 30–40 percent of all cancers can be prevented by changes in the lifestyle and dietary pattern. Cancer risk is elevated by obesity, consumption of no nutrient foods such as carbonated drinks with high sugar and refined flour products that may also result in impaired glucose metabolism, no or low fiber intake, excessive consumption of red meat, and imbalance of omega 3 and omega 6 fats. On the other hand supplementation with flax seeds, particularly its lignan fraction, and good amount of fruits and vegetables will lower cancer risk. Researchers suggest that there is an additional benefit if Allium and cruciferous vegetables are consumed regularly. Further, it is also beneficial to include selenium, folic acid, vitamin B-12, vitamin D, chlorophyll, and antioxidants such as the carotenoids (α-carotene, β-carotene, lycopene, lutein, cryptoxanthin) in the diet (Donaldson, 2004). These supplementations and changes in dietary pattern can help prevent recurrence of cancer in survivors. References Armstrong, B. & Doll, R. Environmental factors and cancer incidence and mortality in different countries, with special reference to dietary practices. International Journal of Cancer. 15: 617–631. Burkitt, D.P. (1969) Related disease—related cause? Lancet 2: 1229–1231. Donaldson, M.S. (2004) Nutrition and cancer: A review of the evidence for an anti-cancer diet. Nutrition Journal. 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