the relationship between dietary habits and cancer risk in Nigeria
CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Cancer remains a formidable global health challenge, with its multifaceted etiology involving intricate interactions between genetic, environmental, and lifestyle factors (Bray et al., 2018). Among the lifestyle factors, diet plays a pivotal role, influencing not only overall health but also potentially impacting cancer development and progression (Colditz et al., 2020). This study delves into the intricate relationship between different dietary patterns and their effects on cancer, aiming to provide comprehensive insights that could contribute to more targeted and personalized prevention and treatment strategies.
The interest in the connection between diet and cancer is rooted in a historical journey through epidemiological observations and experimental studies (Keys, 1980; Doll and Peto, 1981). Pioneering works by researchers like Ancel Keys and Richard Doll have laid the groundwork, establishing correlations between dietary habits and cancer incidence. However, advancements in molecular biology and nutritional science have opened avenues to explore the intricate mechanisms underlying these associations, unraveling the molecular intricacies of how dietary components may influence carcinogenesis.
According to Hanahan, & Weinberg, (2011), diet is an established risk factor for certain cancer development that can be modified and prevent up to 30–50% of all cancer cases. This estimation was derived chiefly from nutritional epidemiologic studies conducted on Western populations from Europe and North American countries. The European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, which involved 13 European countries and the Nurses’ Health Study from the United States (US) are some of the examples of large cohorts that provided ample evidence on the diet cancer associations. Indeed, data from various large cohorts along with meta-analytic studies further our understanding of diet-cancer relations, which were then translated into nutritional recommendations and guidelines aiming to improve public health and reducing risks for cancers and other chronic diseases.
However, Calder, (2013) also added that some of these dietary guidelines cannot be generalized to other populations who live in distinctive areas with local eating habits, preparation, and food availability. As opposed to Western countries for example, in Sub-Saharan Africa (SSA) the traditional African diets are rich in starches consuming local foods such as cassava, tubes, fiber, and plant proteins whereas a general ‘Western diet’ does not include many African typical food items and it is more likely to be high in processed animal products, energy-dense low fiber foods, refined sugars, and sweetened beverages and saturated fats. This highlights the question whether there are cancer-related food items or eating patterns associated with this African diet.
According to National Agency for Disease and Control, in the past decades, Nigeria is experiencing a rapid increase in the incidence of many cancers, and this is causing a growing burden on health services in the country. For example, during the years 2000–2015, the rate of new breast cancer in Nigeria markedly increased from 21.9 per 100,000 (95% CI 15.4–28.3) to 47.9 per 100,000 (95%CI: 41.2–54.6). Also, an increase in the last two decades occurred in colorectal cancer incidence rate by over 300% in the East Africa area. In Nigeria, there are approximately one billion people who are currently living in this content, and despite the rapid rise in the incidence rate of cancer in this area, only a few nutritional epidemiological studies focusing on cancer risks have been conducted. Some of the increase in cancer cases might be attributed to the ‘nutrition transition’; occurring in the urban areas of Nigeria, where people are consuming more ‘Western diet’ replacing their traditional ‘African diet’.
the relationship between dietary habits and cancer risk in Nigeria
Previous studies have shown that ‘African diet’ holds potential nutrients and foods that may be beneficial in protecting them from having chronic diseases including cancer, as opposed to the ‘Western diet’ that increased the risk for multiple types of cancers, and therefore placing African populations at higher risks for cancer. Given the increasing rate in cancer incidence along with nutritional shifts toward ‘Western diet’, studying traditional African foods and their valuable nutrients that may be protective for specific cancer types is timely and warranted. Such evaluations of certain relationships between African diet and cancer will shed light on this complex link and provide suggestions and research directions for future research based on the emerging themes from this field
One of the key challenges in understanding the diet-cancer relationship lies in the diversity of dietary patterns across different populations. This study systematically investigates the effects of various diets, including but not limited to Western, Mediterranean, vegetarian, and ketogenic diets (Willett, 2012). Recognizing the intricate interplay of macronutrients, micronutrients, and bioactive compounds, the research aims to delineate how each diet may modulate cancer risk and progression through distinct molecular pathways. Unraveling the molecular mechanisms connecting diet and cancer is crucial for developing targeted interventions (Hanahan and Weinberg, 2011). From the influence of dietary fats on cell membrane composition to the modulation of inflammation by antioxidants, the study aims to elucidate how dietary components impact signaling pathways involved in cell proliferation, apoptosis, and angiogenesis. Special attention will be given to the role of the gut microbiota, exploring how diet-induced changes in microbial composition may influence the immune system and contribute to cancer development (Turnbaugh et al., 2007).
In the same vein, Hood, & Friend, (2011) reported that scientists have reported an association between nutrition and cancer for decades, attributing roughly 4 to 5 percent of cancer cases annually to poor diet. However, due to limitations in study design and assessment methods, and the heterogeneous nature of cancer pathophysiology, it is complicated for researchers to consistently determine the precise link between dietary factors and cancer risk. Randomized controlled trials of individual nutrients, foods, or food groups are often inconclusive or in contrast with observational studies. Still, epidemiological evidence suggests that diet affects cancer risk and mortality.
As a result, scientists focus on studying overall dietary behaviors as risk factors for cancer. This is more reflective of how people eat: in general, individuals’ dietary patterns are not comprised of isolated nutrients or foods, but rather entire meals made up of a variety of foodstuffs. Although the connection between individual nutrients and cancer may be small, it remains important for researchers to examine potential additive and interactive effects of diet on cancer prevention and risk.
Beyond broad dietary patterns, the research zooms in on the impact of specific nutrients on cancer. This includes scrutinizing the role of omega-3 fatty acids, polyphenols, vitamins, and minerals (Calder, 2013). Understanding the dose-response relationships and potential synergistic or antagonistic effects of these individual components is essential for constructing evidence-based dietary recommendations for cancer prevention and support. Recognizing the heterogeneity in cancer types and individual responses to dietary interventions, the study embraces the concept of personalized nutrition (Hood and Friend, 2011). By integrating genetic, metabolic, and microbiomic information, the research seeks to identify biomarkers that could predict individual susceptibility to dietary influences on cancer. This personalized approach aims to move beyond one-size-fits-all dietary guidelines towards tailored nutritional strategies for cancer prevention and management.
The ultimate goal of this study is to bridge the gap between scientific insights and clinical applications. By understanding how different diets influence cancer at the molecular level, clinicians may be better equipped to advise patients on dietary modifications as part of comprehensive cancer care (Meyerhardt et al., 2012). Moreover, insights gained from this research could inform the development of dietary interventions as adjuvants to conventional cancer therapies and it was on this backdrop that this study seeks to examine the relationship between diet and cancer risk.
1.2 Statement of the Problem
Cancer is a growing public health concern in Nigeria, necessitating a thorough investigation into the intricate relationship between dietary habits and cancer risk within the diverse Nigerian population. With a rich tapestry of cultural practices, varying dietary traditions, and ongoing transitions towards more modernized eating patterns, understanding the specific dietary factors influencing cancer risk is imperative. Despite the recognized impact of diet on cancer development, there is a notable dearth of comprehensive epidemiological studies within the Nigerian context, hindering the formulation of targeted preventive strategies. This study aims to address this gap by examining the interplay of traditional and modern dietary elements, the influence of cultural practices, agricultural methods, and socioeconomic disparities, to unravel the nuanced connections between diet and cancer risk in Nigeria.
The second facet of the problem centers on the unique challenges posed by the increasing prevalence of cancer and the lack of localized research investigating the role of diet in cancer risk. Nigeria’s diverse population, characterized by distinct ethnicities and cultural practices, necessitates an exploration of how these factors intersect with dietary choices to impact cancer susceptibility. Additionally, the lack of a comprehensive understanding of nutritional disparities across socioeconomic strata and their influence on cancer risk poses a significant obstacle. This study aims to dissect these complex dynamics, contributing essential insights to guide public health interventions tailored to the specific needs of diverse communities within Nigeria, ultimately aiming to curb the escalating burden of cancer in the country.
1.3 Statement of Purpose
The primary aim of this study is to comprehensively investigate the relationship between dietary habits and cancer risk in Nigeria.
1.4 Significance of the Study
This study holds significant implications for public health, scientific understanding, and community empowerment in Nigeria. Firstly, it addresses a critical gap in the current knowledge base by providing a nuanced exploration of the relationship between dietary habits and cancer risk within the unique socio-cultural context of Nigeria. As the country grapples with an escalating burden of cancer, the findings from this research can serve as a foundation for evidence-based public health interventions. The identification of specific dietary contributors to cancer risk will enable the formulation of targeted and culturally tailored preventive strategies, ultimately aiding in the reduction of cancer incidence.
Moreover, the study’s significance extends to the scientific community, offering insights into the intricate interplay of traditional and modern dietary elements, cultural practices, and socioeconomic factors that influence health outcomes. By adopting a multidisciplinary approach, the research contributes to the broader field of nutritional epidemiology, advancing our understanding of how diverse dietary patterns impact cancer susceptibility. This knowledge can inform future research endeavors and guide the development of global strategies for cancer prevention.
Furthermore, the study is of paramount importance in empowering local communities with information to make informed dietary choices. The culturally sensitive findings can be disseminated through health education programs, contributing to increased awareness and fostering healthier dietary practices. Ultimately, the study’s significance lies in its potential to influence health policies, improve public health outcomes, and empower individuals and communities in Nigeria to actively participate in their own well-being.
1.5 Justification of the Study
This study is justified by the urgent need to address the increasing burden of cancer in Nigeria and the significant gap in knowledge regarding the specific role of dietary habits in cancer risk within the country. The escalating prevalence of cancer underscores the necessity for targeted research to unravel the unique contextual factors influencing cancer development. Understanding the intricacies of dietary patterns, including the interplay of traditional and modern elements, cultural practices, and socioeconomic disparities, is crucial for developing effective preventive measures.
Furthermore, the study is justified by the potential to contribute valuable insights to both the scientific community and public health practitioners. By adopting a comprehensive approach, including epidemiological, sociocultural, and nutritional analyses, this research aims to provide a holistic understanding of the relationship between diet and cancer risk in Nigeria. The findings can inform evidence-based policies, guide healthcare interventions, and contribute to the global knowledge base on the intersection of lifestyle factors and cancer susceptibility.
Additionally, the justification lies in the potential impact on community health. The study’s outcomes can empower individuals and communities with knowledge about the role of dietary choices in cancer risk, leading to informed decision-making and the adoption of healthier lifestyles. Ultimately, the research holds promise for positively influencing public health outcomes in Nigeria, aligning with the broader goal of reducing the burden of cancer and improving the overall well-being of the population.
1.6 Broad Objective
This research work aims at examining the relationship between diet and cancer risk.
1.7 Specific Objectives
The specific objectives of this study are as follows:
- to examine the relationship between the consumption of fruits and the risk of developing cancer;
- to examine the relationship between the consumption of vegetables and the risk of developing cancer;
- to examine the relationship between the consumption of processed meats and the risk of developing cancer;
- to investigate the role of individual nutrients and dietary components (e.g., antioxidants, fiber, saturated fats) in modifying cancer risk; and
- to assess the effectiveness of dietary interventions in reducing cancer risk among different population groups.
1.8 Research Questions
The following research questions will guide the study on food handling practices.
- What is the relationship between the consumption of fruits and the risk of developing cancer?
- How does the consumption of vegetables influence the risk of developing cancer?
- What is the association between the consumption of processed meats and the risk of developing cancer?
- How do individual nutrients and dietary components (e.g., antioxidants, fiber, saturated fats) modify cancer risk?
- How effective are dietary interventions in reducing cancer risk among different population groups?
1.9 Research Hypotheses
The following hypotheses are formulated to guide the study:
 Hypothesis 1
 (H1): Higher consumption of fruits is associated with a lower risk of developing cancer.
 (H0): There is no association between the consumption of fruits and the risk of developing cancer.
Hypothesis 2
 (H1): Increased consumption of vegetables is linked to a reduced risk of developing cancer.
 (H0): There is no link between the consumption of vegetables and the risk of developing cancer.
Hypothesis 3
 (H1): Higher consumption of processed meats is associated with an increased risk of developing cancer.
 (H0): There is no association between the consumption of processed meats and the risk of developing cancer.
Hypothesis 4
 (H1): Certain individual nutrients and dietary components (e.g., antioxidants and fiber) reduce cancer risk, while others (e.g., saturated fats) increase cancer risk.
 (H0): Individual nutrients and dietary components do not modify cancer risk.
Hypothesis 5
(H1): Dietary interventions are effective in reducing cancer risk among various population groups, with the level of effectiveness varying across different groups.
(H0): Dietary interventions are not effective in reducing cancer risk among different population groups.
1.9 Operational Definitions
Cancer:Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body. These abnormal cells can invade and destroy surrounding healthy tissues, potentially spreading to other parts of the body through the bloodstream or lymphatic system, a process known as metastasis
Diets: A diet is the sum of food consumed by an individual or organism. It can also refer to the practice of restricting oneself to certain foods or the regulation of food intake for improving health, managing weight, or achieving specific goals. Diets can vary widely based on cultural, religious, ethical, or health reasons.
Dietary Habits:Dietary habits refer to the habitual decisions an individual makes when choosing what foods to eat on a regular basis. These choices are influenced by various factors such as culture, personal preferences, and availability of food, economic status, education, and health concerns.
