Around 14·1 million new cancer cases are diagnosed every year, most of which develop from the less economically developed parts of the world. The variation in cancer across the globe and its relative plasticity is strong evidence of the importance of environmental factors in determining patterns of cancer around the world. Therefore, it is preferable to represent nutrition as a critical factor underlying the cause of increasing cancer cases showing variability globally. Diet and activity are the two main components representing dynamic and complex clusters of exposures that vary both within and between people and over time. Diet plays a vital role in cancer management because they are the source of important physiologically functional components. Vitamin A, E, and trace minerals contribute to cancer protection. Large amounts of dietary fibres and other dietary components are associated with a high intake of grains, vegetables, and fruits, reducing the chances of colon cancer and breast cancer. Other natural products are used as an anticancer diet. Combining all the above evidence proves that dietary patterns are healthy and reduce cancer risk, which is proposed as an emerging medical prescription. Dieticians or specialists recommend Anticancer nutritional guidelines to prevent cancer and reduce cancer risk.
Cancer is considered the second most cause of increasing death rate across the globe. Around 14·1 million new cancer cases are diagnosed every year, most of which develop from the less economically developed parts of the world. The WHO has predicted that 23·6 million new cancer cases will be diagnosed every year by 2030, with a significant increase in less economically developed regions. The typical cancer types show substantial variations in cancer patterns as per the economic status. The low-income countries have an increasing number of cases of infection-related cancers such as cervix, liver and stomach cancer. The most commonly diagnosed cancer in men in higher-income countries is prostate, while in less affluent areas, cancers of the oesophagus or stomach are most common. Breast cancer is most common among women in higher- and lower-income countries, but cervical cancer is prevalent in lower-income countries.
The global variation in cancer patterns is not fixed in time and place. When populations migrate to different parts of the world, the cancer patterns alter within two generations to conform to that of their host country. The variation in cancer across the globe and its relative plasticity is strong evidence of the importance of environmental factors in determining patterns of cancer across the world. Therefore, it is preferable to represent nutrition as a critical factor underlying the cause of increasing cancer cases showing variability globally.
Diet and activity are the two main components representing dynamic and complex clusters of exposures that vary both within n and between people and over time. Nutrition and foods are related to about 30% of cancer cases. Several studies represent the association between functional foods and cancer reduction cases (Kuno et al., 2012). Diet plays a vital role in cancer management because they are the source of important physiologically functional components.
Several associations have been found between saturated fat intake and the incidence of breast, colon, and prostate cancers. The information of alcohol more significant than 40 g per day results in a risk to the oral cavity, pharynx, oesophagus, and larynx as alcohol interacts synergistically with smoking to increase risk. Large amounts of dietary fibres and other dietary components are associated with a high intake of grains, vegetables, and fruits, reducing the chances of colon cancer and breast cancer. Insoluble grain fibre shows a more significant association with decreased cancer risk than soluble grain fibre. Vitamin A, E, and trace minerals contribute to cancer protection. The intake of meat and animal products, products rich in animal fats and oils and often cooked at high temperatures, increases cancer incidence, mainly for colorectal, stomach, and prostate cancer. Dietary patterns depend upon regular intake of fruit, vegetables (primarily garlic and cruciferous vegetables such as cabbages, broccoli, brussels sprout and wasabi) and, by consequence, the intake of aliments rich in selenium, folic acid, vitamins (B-12 or D), and antioxidants such as carotenoids and lycopene play a protective role in cancer onset for reducing the risk of breast cancer, colorectal cancer and 60–70% of prostate cancer and 40–50% of lung cancer (Donaldson, 2004).
Combining all the above evidence proves that dietary patterns are healthy and reduce cancer risk, which is proposed as an emerging medical prescription (Lăcătușu et al., 2019). The best diet patterns can reflect several characteristics of an ideal healthy diet.
Significance of diet in cancer prevention
Diet is considered one of the most critical factors for the formation and prevention of cancer. Therefore, there is a need to achieve dietary goals to reduce cancer risk. The American Institute for Cancer Research and the World Cancer Research Fund revealed that almost 30-40% of all cancer types are prevented by appropriate diets, physical activity, and maintenance of proper body weight. Several studies have explained the importance of specific food or nutrients studied for determining their effect on tumour formation and regression or some other endpoint of cancer at a particular site within the body.
Diet has a significant impact on health, while caloric restriction and fasting have predicted benefits for disease prevention and longevity. Strong epidemiological associations have been represented between obesity and cancer, whereas healthy diets help in reducing cancer risk. The intake of a diet based on plant foods like vegetables, whole grains, beans and fruit and following some basic guidelines have effectively reduced cancer risk. The anticancer diet includes a plant-dependent diet that provides fibre intake to the body along with other vitamins, minerals and other antioxidants. Dietary interventions have resulted in improved outcomes in cancer treatment. Also, diet interventions have shown efficacy in overcoming the side effects caused by cancer treatment. The anticancer diet consists of high content food of phytochemicals with potent anticancer and anti-inflammatory properties. The food is an anticancer diet with the properties capable of blocking precancerous cells from developing into malignant cells by interfering directly with tumour cells and by preventing the generation of an inflammatory microenvironment that would sustain the progression of the tumours.
Foods and nutrients with anticancer properties
Researchers have implicated that the use of natural products has been effective in improving the survival rate of cancer patients. Several countries are adopting the anticancer diet, which consists of food materials of dietary vegetables, medicinal herbs, and their extracts or components to prevent or treat cancer. Anticancer diets have been developed consisting of food products adding positive health benefits (Chen et al., 2012). Anticancer diets provide health benefits beyond essential nutrition, and the foods of anticancer diets are similar to conventional foods and are consumed in the form of a regular diet. The food components of an anticancer diet provide the body with the required amount of vitamins, fats, proteins, carbohydrates,& Lowry, 2014). The diet includes ingredients or natural constituents in conventional, fortified, enriched, and enhanced foods. Several naturally occurring compounds are found in food, mainly the antioxidative compounds in plants or their extracts and essential oils, representing potential chemopreventive factors (Sporn & Suh, 2002). Some of the common anticancer foods and nutrients have been discussed below:
- Flaxseeds: It is a sesame-like seed that contains soluble fibre, alpha-linolenic acid (a form of healthy omega-3 fatty acid), and is the richest source of lignans involving phytoestrogens that function as antioxidants. The use of flaxseed has reduced the number and growth of breast tumours.
- Soy: Exposure to soy in the adolescent phase of life helps women to protect themselves from the risk of developing breast cancer. It is effective in lowering cholesterol.
- Garlic: It is considered a cancer-fighting food. Several studies have confirmed that intake of more garlic results in reducing the risk of cancer development such as the oesophagus, stomach, and colon cancer.
- Berries: It consists of powerful antioxidants that hinder the naturally occurring process in the body generating free radicals responsible for cell damage. Therefore, berries are considered the healing food for cancer.
- Tomatoes: It is effective in protecting against prostate cancer in men. It covers the DNA in cells from any damage that leads to cancer risk. It consists of a high concentration of an effective antioxidant called lycopene absorbed by the body, evolving into a cancer-fighting food.
- Cruciferous vegetables: It consists of broccoli, cabbage, and cauliflower which are considered cancer-fighting foods. The components in the veggies help protect from the free radicals that damage the DNA of the cells. It also protects from cancer-causing chemicals helping to reduce tumour growth and enhancing cell death.
- Green tea: the leaves of the tea plant Camellia sinensis consist of antioxidants known as catechins which show efficacy in preventing cancer in several ways involving the protection of free radicals from cell damage. The presence of catechins in tea effectively reduces the tumour size and reduces the growth of tumour cells. Hence, drinking green tea has lowered the risk of cancer development.
- Whole grains: It contains many components that lower cancer risk, mainly fibre and antioxidants. Intake of more whole grains lowers the risk of colorectal cancer, making them a top item in the category of foods to fight cancer. Oatmeal, barley, brown rice, whole-wheat bread and pasta are all the components of food used as whole grains.
- Turmeric consists of an ingredient called curcumin that helps reduce cancer risk. Curcumin can inhibit several types of cancer and helps in slowing the spread of cancer (metastasis).
- Leafy green vegetables involve spinach and lettuce, which are considered good sources of the antioxidants beta-carotene and lutein. Collard greens, mustard greens, and kale are other food components of leafy green vegetables that contain chemicals that limit the growth of some types of cancer cells.
- Grapes: It is considered a rich source of an antioxidant called resveratrol that inhibits the growth of cancer cells from growing and spreading.
- Beans: It contains fibre that helps in reducing the risk of cancer. It also consists of antioxidant properties.
Other sources of the anticancer diet with essential components for cancer prevention are represented below:
|Yellow-orange and dark-green vegetables||α-Carotene||Antioxidant||Increases enhance gap junctional intercellular communication||Rutovskikh et al., (1997)|
|Green leafy vegetables and orange and yellow fruits and vegetables||β-Carotene||Antioxidant||Similar to α-Carotene||Rutovskikh et al., (1997)|
|Tomatoes, water melon, apricot, peaches||Lycopene||Antioxidant||It inhibits the cell growth of various human cancer cell lines||Levy et al., (1995)|
|Orange fruits||β-Cryptoxanthin||Antioxidant||Anti-inflammatory effects; inhibits risks of some cancer||Tanaka et al., 2012|
|Dark green leafy vegetables||Lutein||Antioxidant||Efficient in cell cycle progression and inhibit growth of a number of cancer cell types||Hyang-Sook et al., 2003|
|Green algae, salmon, trout||Astaxanthin||Antioxidant||Modifies gap junction communications||Kurihara et al., 2002|
|Salmon, crustacea||Canthaxanthin||Antioxidant||Free radical scavengers and potent quenchers of reactive oxygen species||Tanaka et al., 2012|
|Brown algae, heterokonts||Fucoxanthin||Antioxidant||Anti-cancer and anti-inflammatory||Tanaka et al., 2012|
|Broccoli, cauliflower, kale||Isothiocyanates||Antibacterial||Lowering risk of lung, breast, liver, oesophagus, stomach, small intestine and colon cancers||Hecht et al., 2004|
|Synthesise in plants||Flavonoids||Antioxidant||Efficient in prevention or treatment of many cancers||Plochmann et al., 2007|
|Yoghurt and fermented foods||Probiotics||Anti-allergy||Inhibiting cancer symptoms||Kumar et al., 2010|
|Soya and Phyto-estrogens||Phyto-estrogens (genistein and daidzein)||Anti-cancer (breast and prostate)||Compete with endogenous estrogens for binding to oestrogen receptor||Limer 2004|
|In most foods (vegetable and cereals etc.)||Fibre||Lowering cholesterol||Lowering the risk of colon and prostate cancer||Wakai et al., 2007|
|Fish or fish oil||Omega-3||Lowering cholesterol||Lowering the risk of breast and prostate cancer||Bidoli et al., 2005|
Anticancer dietary guidelines
Dieticians or specialists recommend Anti-cancer dietary guidelines for the prevention of cancer and reduce the risk of cancer. Some of the smart-eating policies as having been discussed below:
- Limiting the alcohol consumption and intake of foods with folic acid is recommended.
- Exercise regularly and reduce the intake of fat and sugar in food.
- Varieties of fruits and vegetables with about 1/2 cup every nine times a day are recommended. One cup of dark green vegetables and one cup of orange fruit and vegetables is recommended.
- Intake of fish and fish products is recommended two to three times a week while replacing with meats which contain high saturated fats.
- Intake of beans involving soybean products is essential, which is recommended three times a week to take the place of red meat and as a source of folic acid, fibre, and various phytochemicals.
- Several servings of whole-grain foods each day are recommended.
- Substitutes for foods with low calories, fat, and higher nutrients involving fibres should be recommended.
- Lean meats and low-fat dairy products and substitute canola and olive oil for butter, lard, and margarine high in trans fats are chosen.
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