By the end of this chapter, you will be able to:
Mastering these skills will help you build a strong foundation for meaningful nutrition research that can make a real difference in health and wellbeing.
Compiled by: Peter Kamau
Nutrition research is fundamental to advancing knowledge that informs evidence-based interventions in dietetics and public health nutrition in Kenya. Identifying and clearly defining nutrition problems guides researchers to generate relevant data that can influence policy, improve nutritional outcomes, and support sustainable development goals related to health. This chapter explores the foundational aspects of nutrition research, including the nature of nutrition problems, essential research types, purposes, components, historical development, and structuring of research projects within the Kenyan professional context.
A nutrition problem is a condition in a person or a population that results from too little, too much or the wrong balance of food and nutrients, or from the body's inability to use them. Examples are stunting in young children, iron deficiency anaemia in pregnancy, vitamin A deficiency, overweight and obesity, and diet-related diabetes. A nutrition problem becomes a research problem when its size, causes or suitable response are not known well enough to act on. Research is the organised way of finding out.
A dietitian meets such problems every day: a clinic that sees many underweight infants, a ward with frequent pressure sores in malnourished patients, a community unit where anaemia seems frequent. Before any of these can be studied, the dietitian needs the language of research, the main types and purposes of research, the parts of a project, a sense of where nutrition research has come from, and a way to lay out a plan. This topic provides these in the six sub-topics that follow.
Research is a systematic inquiry that uses planned methods to find answers to a question or to test an idea. A hypothesis is a statement, which can be tested, about the relationship between variables: for example, that children who eat a legume-based porridge daily will have higher haemoglobin than those who do not. The nine terms below are the working vocabulary of a study. They are used again in the chapters on design, tools, data collection and analysis.
A population is the whole group of people, animals, items or events that the research question is about. The target population is the group to which the findings are meant to apply, and the study population is the part of it that can actually be reached. Defining the population clearly, by who, where and when, tells the researcher who may be included.
Example: all children aged 6 to 59 months living in the catchment area of one community unit.
A sample is a smaller group chosen from the population to take part in the study. It is used because it is rarely possible to study everyone. A good sample is representative, which means that it has the same mix of characteristics as the population, so what is found in it is likely to hold for the population. A sample that is too small or chosen carelessly gives misleading results.
Example: 120 children chosen from a register of 1,800 children in the community unit.
Sampling is the process of selecting the sample from the population. Methods are in two families. In probability sampling every member of the population has a known chance of being chosen, and the methods include simple random, systematic, stratified and cluster sampling. In non-probability sampling, such as convenience, purposive, quota and snowball sampling, selection depends on the researcher's judgement or on who is available. The methods are compared in the topic Sampling.
Example: for a systematic sample of 120 from 1,800 children, the sampling interval is 1,800 ÷ 120 = 15. The researcher picks a random start between 1 and 15 and then takes every 15th child on the register.
A variable is any characteristic that can take different values in different people or at different times, such as age, weight, haemoglobin level, dietary diversity score or household income. Variables are described by their role:
Variables are also described by their kind. Categorical variables place people in groups, such as sex or nutritional status (stunted or not). Numerical variables are measured on a scale, such as weight in kilograms.
Data are the facts and measurements collected in a study. Quantitative data are numbers, such as weights, heights and nutrient intakes. Qualitative data are descriptions in words, such as the reasons a caregiver gives for stopping breastfeeding. Data collected for the purpose of the study are primary data, and data collected earlier by someone else, such as clinic records, are secondary data. Raw data become information once they are organised and analysed. The types of data are taught in detail in the topic Data collection methods.
A parameter is a numerical value that describes the whole population, such as the true percentage of children in a district who are stunted. The value is usually not known, because it would require measuring everyone, so it is estimated from a sample. Parameters are written with Greek letters: μ for a population mean, σ for the standard deviation and π for a proportion.
The word is used in two ways. First, statistics is the branch of mathematics that deals with collecting, summarising, analysing and interpreting numerical data. Second, a statistic is a numerical value calculated from sample data, such as a mean, a proportion or a percentage, which is used as an estimate of the corresponding parameter.
Example: of 120 children sampled, 36 are stunted. The sample proportion is 36 ÷ 120 = 0.30, or 30 per cent. This is a statistic, and it is used to estimate the parameter, the true percentage in all 1,800 children. The two will differ somewhat, and this difference is called sampling error.
An objective is a statement of what the study intends to achieve. The general objective gives the overall aim, and the specific objectives break it into measurable steps. Each begins with an action verb such as determine, assess, compare, describe or identify, and each can be answered by the results. Poor objectives use verbs that cannot be measured, such as understand or appreciate.
Example of a general objective: to determine the extent of anaemia among pregnant women attending one antenatal clinic. Example of a specific objective: to compare the mean haemoglobin concentration of women in the first and third trimesters. Writing objectives is taught in the topic Formulating research objective.
A literature review is a critical summary of what is already known about the topic, drawn from books, journal articles, reports and other sources. It shows what has been found, where there are gaps and disagreements, and how the new study will add to knowledge. The steps, sources and referencing are taught in the topic Literature review.
Research can be grouped in several ways, and a single study usually fits more than one group. A dietitian chooses the type from the question being asked. The detailed study designs are taught in the topic Types of research design.
Basic research seeks to increase understanding without an immediate practical use, for example a study of how a nutrient is absorbed in the gut. Applied research uses knowledge to solve a practical problem, for example a study of whether a deworming and feeding programme for young children improves height gain. Nutrition research done by dietitians in practice is often applied.
Quantitative research collects numerical data and analyses it statistically, to measure how much or how often. A survey of the percentage of mothers who breastfeed exclusively for six months is quantitative. Qualitative research collects words, observations and stories to explore why people think or act as they do, using interviews and focus group discussions. A study of the reasons a family gives for not feeding eggs to a young child is qualitative. Mixed methods research combines both so that numbers and explanations can support each other.
These three are grouped by the question they answer.
Operational research studies how a programme or service works in practice, for example how well a clinic's nutrition counselling is delivered and where mothers drop out. It is used to improve services and is often done by those who run them.
The purpose of research is the reason it is done. A clear purpose keeps the project focused and tells the reader what use the results will have.
Research adds to what is known. A study that finds a pattern of nutrient deficiency in a group not studied before is an example. Knowledge also comes from checking whether an earlier finding still holds in another setting or time.
Planners and programme managers need evidence to decide what to do and where to spend. A finding on the extent of vitamin D deficiency among a group can shape guidance on supplementation, and a finding on the cost of a feeding programme can guide its budget.
Research tests whether a feeding programme, a supplement, a counselling method or a food-fortification scheme works, by measuring changes in health or nutrition outcomes over time and comparing them with a reference.
Studies of what is linked to malnutrition, such as poor water supply, short birth spacing, low maternal literacy or food insecurity, point to where prevention should be directed.
Conducting and reading research improves a dietitian's ability to judge evidence, to question routine practice and to contribute to better standards of care.
A research project is made of linked parts, and a weakness in one weakens the whole. The parts follow a logical order, and each is taught in detail in later topics.
The problem statement describes the issue to be studied, how big it is, whom it affects and what is not known. A clear statement guides the later decisions. An example is the rising number of overweight children seen at a growth-monitoring clinic and the lack of information about their diets.
The purpose states the aim in a sentence. The objectives, research questions and hypotheses turn it into measurable parts. A study may have questions or hypotheses or both, depending on its type.
The review places the problem in the context of existing knowledge and shows the gap the study will fill.
The methodology gives the study design, the population and sample, the tools for collecting data and the plan for analysing it. It must be described well enough for another researcher to repeat the study.
Data are collected by trained workers using the tools, then cleaned, analysed and interpreted, using statistics for numbers and a systematic method of coding themes for words.
Informed consent, confidentiality and approval by an ethics review committee protect the participants. These are covered in the topic Ethics in research.
The results are reported in writing and shared with those who can use them, such as the clinic, the community and planners.
Nutrition research has grown from the study of deficiency diseases to the study of whole diets, populations and food systems. Knowing how it developed helps a dietitian see why current methods are used.
In 1747 a naval surgeon, James Lind, compared six treatments for scurvy in groups of sailors and found that citrus fruit gave a rapid recovery, an early example of a controlled comparison. In the late nineteenth and early twentieth centuries, studies of beriberi and pellagra showed that diseases could result from the lack of something in the diet and not from infection. Experiments with polished rice in animals helped to show this, and the term vitamin was introduced in 1912. In the 1930s a physician working with children in West Africa described kwashiorkor and linked it to a diet low in protein.
From the middle of the twentieth century, long-term cohort studies followed large groups of people to relate diet to disease. Their findings on diet, blood fats and heart disease shaped dietary advice and showed the strengths and limits of observational studies.
Laboratory measures of nutrient status, standard methods for measuring growth and refined ways of assessing diet improved the precision of nutrition studies. The World Health Organization published its child growth standards in 2006, based on children raised in good conditions in several countries, so that growth could be compared on one standard.
Research widened from individuals to communities. Trials of vitamin A supplementation, iodised salt, fortification and community feeding programmes tested whether nutrition interventions reduced illness and death in populations.
Current work includes diet-related non-communicable diseases, the double burden of undernutrition and overweight in the same community, sustainable and climate-friendly diets, the gut microbiome, and the use of mobile technology for dietary assessment and data collection.
A research outline is the plan of the written work. It lists the sections of a research proposal, which is written before the study, and of the research report, which is written after it. Working out the outline early shows what is missing and keeps the writing in order.
A proposal usually follows this order:
| Section | What it contains |
|---|---|
| Title and abstract | A short title that names the variables and the population, and a summary of the study |
| Introduction | Background, problem statement and justification |
| Objectives and questions | General and specific objectives, research questions and hypotheses |
| Literature review | Existing knowledge and the gap |
| Methodology | Design, study population, sampling, tools, data collection and analysis |
| Ethical considerations | Consent, confidentiality, approval and risks |
| Budget and work plan | Costs, activities and timeline |
| References | Sources cited, in one referencing style |
The report adds the results, a discussion and the conclusions and recommendations, in place of the budget and work plan, and begins with preliminary pages such as the abstract, acknowledgements and list of contents.
Example of a proposal title: Food insecurity and stunting among children aged 6 to 23 months in one village. The title names the independent variable (food insecurity), the dependent variable (stunting) and the population (children aged 6 to 23 months in one village). A general objective for the study would be to determine the association between food insecurity and stunting in these children, and a specific objective would be to measure their length and calculate a food insecurity score for their households.
Create a free account to open more of this chapter.
Free: practical guides, quick cards, workplace scenarios and more.
Create a free accountThis chapter introduces the foundational concepts of nutrition research by defining key terms such as population, sample, variable, data, parameter, statistics, objective, and literature review to establish a clear understanding of the research process. It explores different types of research and outlines their purposes, highlighting the essential components and the historical development of research methodologies. The chapter then guides the identification of research topics by discussing various sources of research problems, the criteria for selecting a viable research problem, and the steps involved in formulating a precise research title. Further, it emphasizes the importance of clearly stating the purpose of the research, developing specific research objectives, formulating relevant research questions, and providing a strong justification for undertaking the study. Finally, the chapter covers the literature review process, focusing on how to critically evaluate information sources and adhere to proper citation and referencing styles to maintain academic integrity. Together, these elements provide a comprehensive framework for determining a nutrition research problem effectively.
At the start of this chapter we promised you would be able to:
Tick each one you can genuinely do.
So, are you there yet?
You're competent when you can confidently do 50% or more of what this chapter promised.
Sign in to record how you're doing.