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| REVIEW ARTICLE |
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| Year : 2021 | Volume
: 6
| Issue : 2 | Page : 115-120 |
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Diet and cancer
Swapan Kumar Paul1, Amrita Ghosh2, Ranabir Pal1, Shrayan Pal3
1 Department of Community Medicine, Venereology and Leprosy, MGM Medical College and LSK Hospital, Kishanganj, Bihar, India
2 Department of Biochemistry, Medical College, Kolkata, West Bengal, India
3 Department of Dermatology, Venereology and Leprosy, MGM Medical College and LSK Hospital, Kishanganj, Bihar, India
| Date of Submission | 21-Aug-2020 |
| Date of Decision | 03-Oct-2020 |
| Date of Acceptance | 11-Apr-2021 |
| Date of Web Publication | 11-Aug-2021 |
Correspondence Address:
Dr. Shrayan Pal
Department of Dermatology, Venereology and Leprosy, MGM Medical College and LSK Hospital, Kishanganj - 855 107, Bihar
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/bjhs.bjhs_80_20
Cancer arising out of diets and protective role of diet from cancers to preserve health and nutritional status is a debate in the healthcare arena. In search of perennial conflict on diet and cancer, researchers of this review emphasized conceptual and contextual details from commonly used dietary items and practices for optimum healthcare model. Twenty-four research studies were identified from 91 potentially relevant data bases and published literatures to collate an updated idea of diet and cancer. Studies were selected on, first; all emerging nutritional plans and related reports on cancer among published literature were sketchily searched. Second, “diet” and 'cancer control was also sourced from different journals, conference proceedings, and different media reports, Third, published reports from apex bodies of global importance like different professional national and international organizations were given due weightage. We have assembled diversity of opinion on prevention and control of cancer in different academic sources. Although there is no paucity of quantitative and qualitative data on diet and cancer, there is dearth of scientific and valid suggestions from scholars on this sensitive issue. In a holistic approach, we require more translational research about diet and cancer with definitive and conclusive evidences for day-to-day application in medical practice for the improvement in clinical approach of this complex debatable paradigm.
Keywords: Cancer, carcinogen, diet, risk
How to cite this article:
Paul SK, Ghosh A, Pal R, Pal S. Diet and cancer. BLDE Univ J Health Sci 2021;6:115-20 |
Many studies have been done to find association between diet and cancer, and experts agree that the food we eat can affect our risk of cancer. There are many hypotheses about cancer; most prominent is that fiber present in fruits, vegetables, and whole grains, protect us against some cancers. Even then no research can show that any eating plan, like a vegetarian diet for example, can lower the chance of cancer. The diet of a person includes both, the foods that can protect and the foods that can increase the risk of cancer. The genes also play an important role in the way diet influences cancer risk. Literature reports that populations consuming diets rich in fatty foods, particularly meat have more cancer occurrence, and much less common in countries eating diets rich in grains, vegetables, and fruits, which contain vitamins, antioxidants, minerals, and phytochemicals to protect the body. On the contrary, recent studies showed that animal products contain potentially carcinogenic compounds which may contribute to increased cancer risk. Hence, eating a healthy and balanced diet with lean proteins, fruits, vegetables, whole grains, and low-fat dairy along with weight control by regular physical activity is the best way to protect us against cancer. By the end of 2020, it is estimated that there will be at least 15 million incident cancer cases, of which 12 million will die.[1],[2],[3],[4]
| Materials and Methods | |  |
Researchers of this review attempted a wide-ranging collection of published literatures by searching various resources; field studies, meeting presentations, and personal communications about studies in which diet and cancer were reported. Through an extensive search in indexed literatures and website-based population survey reports, we identified 24 research publications from 91 potentially relevant articles. All published articles in indexed journals available from various institutional libraries of India and websites on diet and cancer were explored. The search terms included combinations of MeSH terms and empirical taxonomies from diet and cancer explored in Pubmed-entrez, Cochrane Library, Web of Science and the World Health Organization (WHO) Global Health Library, including searching of abstracts from scientific meetings. In the absence of monolithic pattern of reporting and nationally representative database, reports on diet and cancer from all research groups were considered.
Selection criteria
First , study reports of diet and cancer among research literature were sourced; Second, reports containing diet impacting natural history of cancer were identified and collated from all the sources; Third, globally published information from apex bodies, for example, American Cancer Society, Indian Cancer Society, European Code against Cancer, European Prospective Investigation into Cancer and Nutrition, National Cancer Registry Programme of the Indian Council of Medical Research (ICMR), WHO, and reports from Indian research groups were given due weightage for their multi-authored and multi-disciplinary authenticity.
Primary outcome variables: interrelation of diet and cancer.
Diet and cancer
Studies have been conducted with many dietary items by researchers for possible associations with increasing or reducing risk of cancer, but these studies in the laboratory and on animal models were not definitive. This could be possibly tested by doing randomized trial but for ethical reasons, randomized studies are not generally done, knowing that a dietary component may be associated with an increased risk of cancer; many food additives, contaminants and toxins and effect of food processing may have possible associations with cancer risk also.
Acrylamide
Acrylamide is a compound found in tobacco smoke and in some foods (French fries, potato chips, bread and cookies, breakfast cereals, coffee etc). Animal model studies have reported that acrylamide exposure increases the risk for many types of cancer without any consistent evidence.
Alcohol
Alcohol is a known cause of cancer. Researchers have reported that heavy or regular alcohol drinking may increase the risk of cancers of oral cavity, larynx, esophagus, breast, liver, colon, and rectum.
Antioxidants
Antioxidants are chemicals that block free radicals, which damages body cells but research in humans has not demonstrated that antioxidant supplements reduce risk of developing cancer.
Artificial sweeteners
Contrary to the belief, studies conducted on artificial sweeteners such as saccharin, aspartame, sucralose, and cyclamate did not show clear evidence of association with cancer risk in humans.
Calcium
Intake of higher dietary calcium has shown to reduce risks of colorectal cancer, but results of studies are inconsistent. Whereas some studies suggesting increased risk of prostate cancer with high calcium intake.
Charred meat
It has been observed that cooking muscle meat, including beef, pork, fish, and poultry at high temperature such as grilling, frying, roasting, sauteing, broiling, and barbequing results in formation of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons chemicals, which may cause cancer in animals, however human studies is unclear.
Glucosinolates
Present in cruciferous vegetables such as cabbage, broccoli, cauliflower etc., break down into several compounds, which have shown anti-cancer effects in animal cells, but human studies are less clear.
Allicin
Present in garlic has demonstrated anti-cancer properties. Other studies have found an association between garlic intake and a lower risk of specific types of cancer, including stomach and prostate cancer without any definitive evidence.
Catechins
(Antioxidants): in Tea, a polyphenol compound supposed to be anticancer, but results of epidemiologic studies and clinical trials have been inconclusive.
| Diet for Cancer Patients, a Balanced Approach | | |
Although there are many studies to support strong association between diet and cancer, there is no single food that can prevent cancer. Instead, a balanced dietary approach is supposed to be the best, which may reduce cancer risk by 70% and even help in recovering. There are foods, which fights cancer by a process called as anti-angiogenesis by blocking the blood vessels that supplies cancer cells, but this depends largely on how they are cultivated, processed, stored and cooked. To maintain a proper diet in cancer patients is not an easy task, as during treatment they have nausea and in addition during radiation therapy, their taste buds might get affected, leading to loss of appetite. As such balanced diet including nutritious foods can help patients maintain their body weight and improve stamina, which can help to better tolerate the side-effects of treatment and also recover faster. Hence, these patients should not have too many dietary restrictions; the idea is to serve them their favorite foods, keeping in mind to avoid excessive intake of salt, sugar and oil. Furthermore, cooking methods are important for these patients, for example, steaming, boiling, and stir-frying to be preferred over baking, deep frying, barbequing and grilling. A healthy and balanced diet as per required energy by age group from diet is more important for cancer patients and so they must eat well even if there is loss of appetite. [Table 1]. It is sometimes better to try new foods even if they were not liked in the past; due to taste changes, may taste good during treatment. Few dietary items must be included in the diet of cancer patients are:[5],[6],[7],[8],[9],[10],[11],[12],[13],[14]
Carbohydrates
Rice, noodles, chapatti and pasta; wholegrain breads and crackers, potatoes, beans, oatmeal, cornflakes, and dairy foods; honey, consumed in moderation for its anti-bacterial and anti-fungal properties which may help in preventing infections.
Ragi (Eleusine coracana, family gramineae)
A population-based cancer registry was started at Bangalore, South-India, as part of the National Cancer Registry Programme of the ICMR, which revealed evidently high risk of oral cancer in people consuming ragi as staple dietary component compared to those not using it.[14]
Proteins
Fatless meat, fatty fish, poultry, eggs, dried beans, nuts, pulses, peas and soy foods.
Vegetables
Studies reported a lower risk of cancer with a higher consumption of vegetables and fruits. They contain antioxidants and phytochemicals, which help prevent cancer by anti-inflammatory properties by induction of Phase II enzymes like glutathione-S-transferases. Cabbage has chemical compound Indole-3-carbinol, which helps fight estrogen, responsible for breast cancer. This compound converts harmful effects of estrogen into a safer compound. Cauliflower: many studies have shown that cauliflower is linked to fighting cancers of bladder, breast and prostate. In addition it also has anti-inflammatory properties and helps the body to detox. Mushroom has plenty of vitamins and iron. They have anti diabetic, anti-allergic properties and also prevent tumors. In addition mushrooms are known to impede the side effects of chemo therapy and radiation. Broccoli contains sulforaphane, which prevents development of tumors. Carrots are rich in beta carotene and falcarinol have anti-cancer properties; whereas some research groups reported beta carotene as carcinogenic. Consuming carrots can help fight cancers related to bladder, prostate, breast, and intestine. Sweet potatoes contain polyphenol antioxidants like caffeic acid and di and tri caffeoylquinic acids, which help in fighting cancers of lung, gall bladder, kidney, liver, and breasts.
Fruits
Citrus fruits are rich in Vitamin C; Bananas, peaches, kiwi, pears, mangoes, and strawberries are rich in diverse vitamins and fiber. Grapefruit is enriched with flavonoids, which reduces cancer cells in colon cancer. Grapes contain proanthocyanidins that is beneficial of cancers of breast, colon, and prostate. Watermelon - Lycopene, a powerful antioxidant is present in watermelon is helpful in fighting cancer. Tomatoes contain antioxidant lycopene and Vitamin C, which helps fight cancer. Papaya is rich in beta carotene and lycopene, fights free radicals. Further, isothiocyanates in papaya have been reported to protect against cancer. Oranges and lime contain limonene, which boosts immunity and produces cancer killing immune cells.
Berries
Ellagic acid present in strawberries and raspberries is responsible for preventing skin, lung, bladder, and esophagus cancer.
Different types of phytochemicals are available naturally from vegetables and fruits, so it is best to eat a variation every day.
Flaxseeds
Flaxseeds have been reported to reduce spread of prostate cancer in men and breast cancer in women.
Spices
Animal studies reported cinnamon prevent spreading of cancer cells. Also, curcumin, present in turmeric have anti-cancer properties. Garlic contains sulfur compounds that boost immune system, helping natural defense against risk of stomach, pancreas, colon, esophagus, and breast cancer. Turmeric has many medicinal properties. Curcumin (antioxidant) present in turmeric helps slow down the growth of cancer.
Beans and legumes
Beans and legumes with high fiber content are protective against colorectal cancer.
Nuts
Consumption of nuts on regular basis may be linked to a lower risk of certain types of cancer.
Soy
Soy products help lower the risk of prostate and breast cancer.
Olive oil
Many studies reported olive oil reduces cancer risk.
Fish
There's evidence to suggest that eating fresh fish may help protection against cancer (colorectal cancer).
Dairy
There is evidence to suggest that eating dairy products may have varied effect, for example, moderate intake raw milk, fermented milk products and milk from grass-fed cows, may protect from colorectal cancer but high consumption of processed dairy products is associated with increased risk of cancer, may be due to hormones present in milk from pregnant cows.
Green tea
Contains polyphenols and has antioxidant properties, which has been reported to be useful in preventing cancer.
| Alcohol and Cancer | | |
Alcohol consumption has been associated to various types of cancer. A meta-analysis of more than 200 studies found that alcohol is directly proportional to occurrence of cancers of the oral cavity, pharynx, esophagus, and larynx, including statistically significant increases in the risk for cancers of the stomach, colon, rectum, liver, female breast, and ovaries. Coexisting tobacco use and alcoholism, which is common, increases alcohol's effects on cancer risk of the respiratory and upper digestive tract. However the study could not identify a lower level of alcohol below which no increased risk for cancer was evident. Researchers are still trying to discover why alcohol increases cancer risk, which might be related to two chemicals ethanol and acetaldehyde (made when alcohol is digested by the body) that may damage the DNA of healthy cells. Alcohol causes rise in estrogen level (risk factor for breast, ovarian, and uterine cancers) in the blood due to its breakdown. Drinking alcohol may weaken the body's ability to process and absorb important nutrients, including: Vitamin A; Vitamin C; Vitamin D; Vitamin E; Folate Alcohol can also cause weight gain, which also increases cancer risk. There is no short cut to completely prevent causing of cancer by alcohol; however, steps can be taken to lower alcohol-related risk by: For women, limit alcoholic drinks to not more than 1 drinks/day and up to 2 drinks/day for men. Stop heavy drinking (c.f., more than three drinks for women, more than four drinks for men) to avoid increased risk for certain cancers. Red wine is no exception as there is no added and conclusive evidence in favor to prevent cancer. Tobacco has synergistic adverse effects with alcoholic beverages by further increasing the risks of developing cancers of oropharynx, and gastrointestinal tract and respiratory tract. Folate found in green leafy vegetables, fruits, and peas may give protection against breast cancer.[15],[16],[17],[18]
| Cancer Risk and Diet in India | | |
In spite of a diverse population with equally diverse diets, cancer rates in India are lower than the western countries. Of late cancer rates are showing a rising trend in Indians too due to migration of population to the cities, rise in life expectancy and changes in lifestyles. It has been observed that cancers of prostate, colon, rectum and lung are lowest in India. At the same time oral and esophageal cancers are highest. Diet in India is very diverse, which is not seen in other countries. There are many dietary patterns, which have trickled from one generation to other through cultural and religious teachings for years. Studies have been done focusing on vegetarianism, spices, and food additives, but not much is known about association of cancer and Indian diet. Researchers have also taken up studies on turmeric (common Indian curry spice) cumin, chillies, kalakhar, Amrita Bindu, and various plant seeds for their apparent cancer preventive properties.[19],[20],[21]
| FAQs about Cancer | | |
- What precautions to be taken in case of low immunity during cancer treatment? Low immunity is transient; so no special diet is required. During intensive chemotherapy or a bone marrow transplant, precautions to be taken, when immunity is low: Avoid pate, raw eggs and any product containing raw egg, seafood, probiotic food products, unpasteurized milk and cheeses made from unpasteurized milk; Ensure clean hands while cooking and before eating; Food must be well-cooked, especially meat and fish; Raw foods, such as salads or fruits must be washed thoroughly; Check the best before dates for stored item; Very careful while eating out
- Whether to take dietary supplements? There is no need for dietary supplements when patient is taking a healthy and balanced diet. In case there is difficulty in eating or where patient is unable to absorb the nutrients such as in case of stomach cancer surgeries, multivitamin or mineral supplements may be required, whereas, in cases of osteoporosis calcium and Vitamin D supplements are helpful. In addition, there is evidence that taking high doses of supplements like vitamins can increase the risk of cancer in some
- Whether super foods will help? There is no evidence that any particular food will help in cancer, instead one should have healthy and balanced diet
- Whether a dairy-free diet to be taken? Though there are many studies to show association between high dairy products and cancer (particularly breast and prostate cancer), but could not establish a clear link so diary free diet is not recommended. Dairy products are good source of protein, calcium and some vitamins, but can be high in fat, which can increase weight. Calcium present in dairy is helpful to reduce the risk of bowel cancer
- Whether sugar increases risk of cancer? It does not directly increase the risk of cancer, but sugar leads to weight gain, which may be the risk factor for cancer
- Whether organic food is better in cancer? So far, no studies have been done to find out whether an organic diet is better at stopping cancer. Instead pesticides used in nonorganic farming are implicated in causing cancer. Though genetically modified foods have been proved to be safe, but long-term effects are unknown
- Whether anti-cancer diets helpful? Of late there has been a flood of publicity about alternative diets for treating cancer over the past few years. At present, there is no evidence that so called anti-cancer diets can shrink a cancer, increase a person's chance of survival, or cure the cancer
- How much proportion of food energy (fat, saturated fat, and free sugars) to be included in diet?
- How many portions of vegetables and fruits to eat? One has to consume at least 5 portions of fruits and vegetables per day. It is seen that most people are not reaching these recommendations
- Foods to avoid as a cancer patient: Deep fried, grilled, barbequed, baked meats since subjecting animal protein to high heat creates carcinogenic by-products called HCAs; Excessive intake of salt, sugar and oily foods; Red meat and processed meat products namely bacon, sausages, ham; preserved foodstuffs like pickles, and jams contain nitrites which are carcinogenic; Minimise alcohol; In addition, cancer patients should avoid excessive intake of vitamin supplements, as they act as antioxidants and can interfere with chemotherapy when taken in large doses.[22],[23],[24]
| Conclusion | | |
In today's world, almost everything we come across in day to day life can increase cancer risk; as such cancer has become unavoidable. Many studies have been done on different dietary items suggesting both increasing and reducing risk for cancer, but few have significant supporting scientific evidence; whereas obesity and alcoholism are confirmed causes of cancer. Alcohol is a carcinogen and increases cancer incidence and mortality. There is currently no confirming evidence that including vitamins, antioxidants, or other micronutrients in diet reduces cancer. Hence, the best way is to recommend for weight management and eating a healthy and balanced diet including mainly vegetables, fruits, whole grains and fish, and a reduced intake of red meat, animal fat, alcohol, and refined sugar with special emphasis on proper methods of cooking and processing dietary items.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1]
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