J Cancer Prev 2022; 27(4): 208-220
Published online December 30, 2022
© Korean Society of Cancer Prevention
1Centre of Healthy Ageing and Wellness, Faculty of Health Sciences, The National University of Malaysia, Kuala Lumpur, Malaysia, 2Genome Health Foundation, North Brighton, SA, Australia
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Individual dietary patterns may be influenced by diet-related behaviours, which may eventually play a significant role in contributing to colorectal cancer risk. As nearly half of colorectal cancer cases can be prevented through diet and lifestyle modification, in this study, we aimed to present an overview of the literature on diet-related behaviour and its effect on colorectal cancer risk among adults. Articles published from 2011 until July 2021 were selected. Out of the 1,198 articles retrieved, 25 were analyzed. There were 16 case-control studies, and nine of them were cohort studies. As a finding, the instruments used in this review were food frequency questionnaires (n = 23), followed by a semi-structured interview (n = 1), and diet records (n = 1). We demonstrated that unhealthy diet-related behaviours are linked to an increased risk of colorectal cancer in adults and those food frequency questionnaires or food records are common instruments used to collect diet-related behaviours. This article imparts the research trends and directions of colorectal cancer risk factors and shows that diet-related behaviour varies and changes over time.
Keywords: Colorectal neoplasms, Feeding behavior, Cooking method, Eating
According to the World Health Organisation, cancer is the world's leading cause of death and is responsible for an estimated 10 million deaths in 2020 . Cancer was responsible for approximately one in every six deaths globally. About 70% of cancer deaths occur in countries with low and medium incomes, and the mortality rate is also projected to increase in numbers by the year 2040 [2,3]. Colorectal cancer (CRC), which refers to both cancer of the colon and the rectum, is one of the most common types of cancer worldwide, accounting for 10% of worldwide cancer incidence with 9.4% cancer mortality . Aside from dietary habits, other factors, such as age, lifestyle, and nutritional status, have a significant impact on the incidence of CRC [5,6].
CRC is thought to develop from colorectal adenoma, a benign and non-cancerous tumour that later progresses to become a precursor for the malignant and invasive form of adenocarcinoma; colorectal adenoma and sporadic CRC share common risk factors . It may take many years for the progression from a non-cancerous form to a cancerous one . The formation of colorectal adenocarcinomas can be classified into three patterns: sporadic, hereditary, and familial . The non-hereditary risk factors, such as dietary and lifestyle behaviours and exposure to environmental genotoxins, are linked to the onset of sporadic CRC. In contrast, hereditary and familial CRC are linked with inherited mutations of certain genes and their interaction with environmental risk factors .
Nowadays, the study of the risks of CRC is becoming an important research focus since most of the risk factors are modifiable and preventable . Dietary habits and related behaviours can significantly alter nutrient composition, such as changes in patterns of energy, macronutrients, and micronutrients, which can lead to the development of some cancers . The majority of studies on CRC risk factors have been conducted in Western countries, but studies in Malaysia are lacking and need to be explored more in depth. Local studies show that males having a high percentage of body fat, smoking, and having a history of cancer in the family, are inclined to have an increased risk of CRC .
In addition, high fat and calorie intake and red meat consumption exceeding 100 g per day increase the risk of colorectal adenoma . The determination of dietary patterns is important to know because the nutrients from different types of foods consumed together will affect the individual’s health. Compared to determining the intake of food types one by one, the determination of dietary patterns will provide a better quality and more comprehensive profiles of a diet . Thus, dietary patterns should be determined and analysed to improve the ability to assess stronger effects as a result of the cumulative effects of nutritional characteristics and allow the evaluation of interactions between synergistic components .
It has previously been observed that the type of meat, cooking method, and temperature influence the amount and types of carcinogens . Red meat intake and smoking are significantly associated with increased CRC risk . The cooking process of meat can produce carcinogens, such as heterocyclic aromatic amines and polycyclic aromatic hydrocarbons. Similarly, processed meat products, such as cured and smoked meat, may also contain carcinogenic chemicals like N-nitroso compounds and polycyclic aromatic hydrocarbons formed through meat processing . While the role of dietary patterns assessed by principal component analysis has also been increasingly evaluated, there is a paucity of data on food consumption behaviour. There are increasing reports suggesting that the need for diet-related behaviours could potentially lead to significant changes in limiting the risk of CRC. Obesity has been linked to increasing and varying snacking on unhealthy foods, cooking methods, meal frequency, and food type intake [19,20]. Due to the detrimental effects that poor dietary decisions have on general health, particular attention should be paid to these alterations as they may increase cardiometabolic risks [19,21]. Thus, in this review, we conducted a comprehensive analysis of food consumption behaviour considering meal frequency, food intake, and types of cooking methods.
This scoping review was conducted on diet-related behaviour and the risk of CRCamong adults following Arksey and O’Malley’s  framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines . The five stages that were applied are described below.
As mentioned previously, the purpose of this study is to present an overview of the literature on diet-related behaviour among adults with CRC. The research question was identified to direct the review and determine the relevant studies. Thus, this scoping review was intended to answer the following research questions:
What are the instruments used to identify diet-related behaviour among adults with CRC?
What diet-related behaviours are prominent due to their effect on CRC risk in adults?
Relevant studies published between January 2011 and July 2021 were identified for this scoping review. We intended to find evidence for five years; however, due to limited data, we expanded our search to ten years. The Population, Concept, and Context (PCC) in Table 1A below was used to guide at this stage based on the following mnemonic PCC, where the target population of this scoping review was adults with CRC and their diet-related behaviour. The MEDLINE Medical Subject Headings for key terms related to diet-related behaviour and CRC were carefully analyzed by two reviewers (NMABM and RS). Thus, these are the search terms used in this scoping review: (“Diet behaviour” OR “Food consumption” OR “meal timing” OR “dietary habit” OR “Dietary intake” OR “Diet” OR “Cooking methods”) AND (“Behaviour” OR “habit” OR “Practices”) for food consumption behaviour and (“Colorectal Cancer” OR “Colorectal neoplasm” OR “colon cancer” OR “rectal cancer” OR “bowel cancer”).
The inclusion criteria for the articles were as follows: 1) full-text articles from peer-reviewed journals and 2) a retrospective study aimed at understanding diet-related behaviour in CRC patients. Retrospective studies were selected to determine the effect of their dietary behaviour before subjects were diagnosed with CRC. Studies were excluded if they did not fit into one of these categories. In addition, any review articles and all other secondary sources were excluded from the study to make sure that only analysis of primary data was performed.
Three databases were queried in this review: PubMed (EMBASE), Science Direct, and the Cochrane Database of Systematic Reviews. We believe that these three search databases would collect relevant journals in the field of interest. In summary, 1,471 articles were retrieved using the above keywords and databases.
With guidelines from PRISMA-ScR any duplicated titles were removed (n = 273), leading to 1,198 articles to be considered. After these articles were reviewed by NMAM and RS, about 1,173 of them were excluded due to the study population involving animals, in vitro or in vivo studies, bioactive components, and an irrelevant population. Only 25 articles were finally included in the review. The methodological quality of individual studies was not conducted, as this is not a compulsory step in scoping reviews .
At this stage, all of the selected data extracted from the journal databases were organised in Microsoft Excel. The extracted data include the author(s), publication year, country, study design, objectives, type of instrument used, and the findings. We presented the data in four separate tables under the results section of this review.
Under Arksey and O’Malley’s  framework, the last stage was to categorise the relevant findings based on the research questions and focus on diet-related behaviour among adults with CRC. The flow diagram for this scoping review has been summarised in Appendix 1.
Following Arksey and O’Malley’s  framework and the inclusion criteria outlined above, the literature search found 25 relevant studies (Table 1B). As mentioned in the methods section, the study on food consumption behaviour and the incidence of CRC was still limited, which led to extending the scope of the target population. The sample size of participants involved ranged from 222 to 478,994. Meanwhile, the age range of participants was between 16 and 87 years old. The studies comprised nine cohort studies and 16 case-control studies. Among the 25 articles, seven were from the United States, four were from China, two each from Japan, Korea, and Norway, and one each from Australia, Pakistan, Brazil, Iran, Scotland, Greece, Spain, and Jordan. All the studies recruited participants from hospital and community-based settings.
Most of the studies used a food frequency questionnaire (FFQ) (n = 23); two used a semi-quantitative food frequency questionnaire, and one used a structured questionnaire (Table 1B). All the information on dietary intake was collected via questionnaire, and 16 studies were retrospective, while nine were prospective. The settings of these studies included hospital-based and community populations. Some articles studied a single type of dietary intake, while others tackled multiple dietary intakes and types of cooking methods.
Studying diet-related behaviour and the incidence of CRC requires reliable and valid methods for the assessment of diet-related behaviour. Nineteen of the reported questionnaires dealt with food frequency, five were semi-quantitative, and one was structured. The purpose of most dietary methods was to obtain information on nutrient intake, although some were also concerned with information about food groups or specific food items. In few instances, the dietary method was concerned only with collecting data on food groups or items. Some used a semi-quantitative questionnaire to grasp a better idea of diet-related behaviour, as the FFQ may not capture it.
This review identified three different diet-related behaviours in these studies. They include (a) cooking methods (Table 2), (b) meal frequency (Table 3), and (c) food intake (Table 4). Three studies investigate the type of cooking method that increases the risk of CRC among adults. The majority of participants preferred barbecued meat, followed by pan-fried meat, and microwaved meat was the least preferred . However, Joshi et al.  reported that pan-fried beefsteak, sausage, spam, ham, or bacon (especially among tumour mismatch repair proficiency) and a diet high in oven-broiled short ribs or spareribs had a strong positive association with the risk of CRC. Apparently, those who preferred their hamburgers well-done or very well-done had a 27% higher chance of developing CRC (95% confidence interval, 0.95–1.69) than those who preferred their hamburgers rare or medium-done, but none of these differences were significant . Interestingly, a preference for rare-cooked meat was associated with a lower risk of CRC in both red and total meat .
Two cohort studies focused on the association between meal frequency and the CRC risk [28,29]. One study found that eating four or more times a day lowered the CRC risk by 28 to 38% as compared to eating fewer than three times a day . This was supported by Kontou et al. : the higher the daily meal frequency, the lower the likelihood of having CRC after adjusting for age, sex, body mass index (BMI), physical activity status, smoking habits, and family history of CRC. In contrast, a study conducted by Mekary et al.  believed that an increase in meal frequency, increased snack frequency, or breakfast pattern had no association with the incidence of CRC. There was no evidence of an increased risk of CRC when the highest meal frequency (6–8 times a day) was compared with the reference category of three times a day .
It has been reported that dietary vitamin D, calcium-rich dairy products, whole grains, and fibre were shown to be protective against CRC risk [31-34]. A case-control study conducted in Korea reported an association between green tea intake and the risk of CRC . According to this study, moderate green tea intake elevated the risk of CRC; however, the risk was reduced when a higher amount of green tea was consumed . Polyphenols are mostly found in a wide variety of plants, food, and beverages including green tea, and their protective effect on CRC risk is related to their antioxidant, anti-atherosclerotic, anti-inflammatory, and anticancer properties [36-38]. Furthermore, Ashmore et al.  discovered that a supplemental iron intake of more than 18 mg/d may increase the risk for CRC in a study on the association of dietary and supplemental iron and CRC. However, no significant associations were observed for dietary iron, total iron, or heme iron intakes.
Aside from sugar-sweetened beverages, poor dietary behaviour indicated by high-energy snacks food, which is defined as high-sugar foods, including pudding and desserts; chocolates, nuts, and crisps; and biscuits, cakes, and high-fat foods, was positively associated with the risk of CRC [40,41]. Meanwhile, Theodoratou et al.  also found that individuals with a high BMI were associated with an increased CRC risk, even when consuming a high intake of fruit or vegetable juices (fresh or ready-to-drink juice). As for total fat and fatty acid intakes,  suggested that total fat, saturated fat, monounsaturated fat, and n-6 polyunsaturated fat intakes were not related to the risk of CRC. However, increased consumption of n-3 polyunsaturated fat might reduce the risk.
Most of the articles reported a positive association between cooking methods and the risk of CRC. The current study found that cooking at high temperatures and long exposure to heat will result in the formation of a genotoxic agent, such as heterocyclic amines and polycyclic aromatic hydrocarbons, which are related to CRC formation. Therefore, cooking methods like grilling, barbecuing, pan-frying muscle meat, or cooking over a direct flame were found to have a positive association with CRC [27,28,43]. Takachi et al.  explained that meats like beef, pork , and fish produced carcinogens like heterocyclic amines when cooked at a high temperature, which relates to the possible mechanism associated with CRC. Tabatabaei et al.  agreed that relatively high temperatures affected mutagenic activity when they studied cooking methods and the level of doneness that can influence the content of by-products in meat.
Minimal studies have looked at the association between meal frequency and quality and the risk of CRC. Two studies have shown that higher meal frequency was associated with lower colon cancer risk among subjects with higher insulin sensitivity, a higher physical activity level, and a BMI below 25 kg/m2 [28,29]. According to Kontou et al. , the higher the number of meals daily, the lower the likelihood of having CRC, because frequent meals have been linked with a better lifestyle and diet as well as better blood sugar control, whereas a lower number of meals (< 3 times daily) were associated with elevated visceral fat and insulin resistance, an increase in alcohol consumption, and lower leisure physical activity [45,46].
These current findings are in contrast to previous case-control studies where a positive association was seen between meal frequency and CRC risk [47,48]. In this review, we discovered a limitation in terms of meal frequency, where it is solely measured in how many meals per day participants consume, and not all studies consider whether it is a healthy balanced diet or vice versa. It is more practical and relevant to record the types of meals, nutrients, and portion sizes compared to meal frequency alone . These findings should be interpreted with caution because our bodies’ mechanisms interact differently with increasing or decreasing meal frequency, as it involves the concentration of bile acids secretions, serum glucose, and insulin levels, which may have a negative effect on cancer growth [50,51].
According to the World Cancer Research Fund, grains and their products, poultry, coffee, tea, omega-3 fatty acids, shellfish, and other seafood have limited to no conclusive evidence with regards to association with cancer . Furthermore, consuming whole grains, dietary fibre, and dairy products is strongly associated with decreasing the risk of CRC . A meta-analysis revealed a nonlinear inverse relationship between fruit and vegetable consumption and CRC . Following the present results, previous studies have demonstrated an inverse to no association when examining whole grains, fibre, polyphenols, dietary vitamin D, calcium, and dairy products [32,33,35,54-58].
In a recent survey by the National Health and Morbidity Survey 2019, 95% of adults in Malaysia do not meet the recommended number of servings of fruits and vegetables a day and are taking less than that requirement. It is important to meet fruit and vegetable requirements as it will also provide therapeutic effects from natural compounds like polyphenols and aid in the prevention of diseases . Polyphenols from natural sources are found to have a protective effect on cells against oxidative stress . Some examples of foods and food materials that contain polyphenols include cereals and legumes (barley, corn, nuts, oats, rice, sorghum, wheat, beans, and pulses), oilseeds (rapeseed, canola, flaxseed, and olive seeds), fruits and vegetables, and beverages (fruit juices, tea, coffee, cocoa, beer, and wine) .
We included a range of diet-related behaviours (e.g., cooking methods, meal frequency, and food intake), which provided an opportunity to assess the effect of this factor on the risk of CRC. Some limitations need to be clarified in this review. Despite the fact that most studies used validated and reliable food frequency questionnaires or dietary intake questions, dietary intake was assessed using self- or parent-report, which was susceptible to measurement error and thus may have influenced the results. Researchers must look at the molecular level to dig into what diet-related behaviours cannot capture the risk of CRC in order to come up with more precise results for a dietary pattern guideline . In terms of study design, some of the cohort and case-control studies included in the review were only conducted from 2011 until 2021 and may be subjected to selection bias and recall bias depending on the length of follow-up, sample size, and studied region.
We have shown in the present review that instruments used to collect diet-related behaviours are food frequency questionnaires or food records, and unhealthy diet-related behaviours are associated with an increased risk of CRC in adults. Therefore, this article can be applied not only to CRC but also to case studies of cancer, and it is suitable to provide readers with wide-ranging information. Diet-related behaviour alone is not enough. Thus, biological markers seem to be substantial and can contribute greatly to the prediction of CRC.
Malaysian Ministry of Higher Education Grant (FRGS/1/2020/STG02/UKM/02/5).
No potential conflicts of interest were disclosed.
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