Dietary assessment method involves the collection of information on food and drinks consumed over a specified time that is coded and processed to compute intake of energy, nutrients and other dietary constituents using food composition tables.

Epidemiological study is the foundation for disease control and prevention through tracking the prevalence of the disease, natural history of disease and identifying the cause of diseases.

Dietary Assessment Methods

DIETARY ASSESMENT METHODS FOR EPIDOMOLOGICAL STUDIES

Diet of a person is directly related to disease. Changes in dietary habits can reduce the risk of disease by one third. Healthy changes in diet can reduce the risk of cancer, cardiovascular diseases, obesity and many other leading diseases.

Biochemical markers are the specific type of bio chemical produced in human body before and during disease generation and can may be the early sign and symptom for disease identification.

Dietary Assessment Methods:

There are two methods through which dietary assessments can be done these are:

  1. Objective observations
  2. Subjective report method

Dietary Assessments by Objective Observations:

There are two methods of objective observations:

  • Duplicate Diet Approach
  • Food Consumption Record

Duplicate Diet Approach:

It involves the collection of duplicate diet sample and its direct analysis. It involves the actual intake of information throughout a specific period. the observations that are taken through this method are not considered as much accurate so it’s not suitable for large scale studies.

Food Consumption Record:

Objective observation method in which records are taken by trained staff at household level. It also involves the actual intakes of information throughout a specific period. As this method is limited to household levels and are not suitable for those who are majorly eating foods outside the home frequently. Individuals dietary consumptions are not accurate.

Dietary assessments methods through subjective approaches:

Subjective approach methods that asses an individual intakes include:

  1. The 24-hour dietary recall method
  2. Dietary record (DR)
  3. Dietary history
  4. Food frequency questionnaire (FFQ)

The 24-hour Dietary Recall method:

Subjective observation method provides quantitative information about an individual diet by respondents about the quantity and type of food and beverages intake about the previous 24 hours.

The advantages of this method is that it provides a quick way to administer, inexpensive and cheap method for taking observation, only require short term memory as it include only 24 hours, also considered as most accurate method with high precision and it can be administered to low literacy populations.

The limitations of this method include it provides a difficulty in precisely estimating what, how and how much food and beverages are intake, it only requires the 24 hours’ period and a single 24 hours does not estimate the usual intake of a person.

Dietary Record (RD):

A food dietary record also called a food diary is a self-reported account of all foods and beverages and possibly dietary supplement consumed by a respondent one or more days. This method is also inexpensive and provide accurate observations of the respondents as it does not only limit to single 24 hours and it also does not depend on the memory of the person as the respondent itself immediately jot down what they had eaten.

Dietary history:

The dietary history method is a detailed retrospective dietary assessment method which obtain detail of individual food and comprehensive information about food eaten less regularly. It is used to describe the usual food or beverages intakes over month or a year.

All of the methods through which dietary assessments can be done Dietary history is considered as the most accurate method as it includes the data of respondents over a specified period of time. Both open - ended and close – ended questionnaires administered by a trained interviewer. The limitations of this study is that it is time consuming and costly and not considered as suitable for epidemiological studies.

FFQ (food frequency questionnaire):

FFQ abbreviated as food frequency questionnaire is a subjective dietary approach method consist of a finite list of foods and beverages with response categories to indicate usual frequency of consumption  over the time period queried.

It is a self-predefined or interviewer administered format. It also required a relatively long or specified time period of about weeks, months or years. It asses the usual dietary intake in a simple way, not too much costly and time saving method and considered as the suitable method for epidemiological studies. It usually consists of close ended questions and most of the researchers and thesis doing students are using this method for their ease and accurate results.

How to make a FFQ?

As this method is considered as the most widely used method for epidemiological studies, for researches, for thesis work, to conduct a survey and to make a general estimation for anything. There are some tips through which one can produced an effective questionnaire these are:

  • Keep in mind the underlying assumption:  while making a FFQ one should kept in mind the group of people which are the representative of whole population and the people on which we are doing our research and drawing our conclusion. Like if our underlying assumption are PhD students than well will send our FFQ to PhD students and these students will be the group on which we want to do our research.
  • Format a question depends on methods: format of questions in your FFQ will be depend on the method you are using for analysis of your research in future. Statistical methods, probability method and many other methods can be used for a research and the questions will be accordingly the method you are using.
  • Avoid open ended questions: in any questionnaire there are two types of questions Open-ended questions and Close-ended questions. In open ended questions a participant has to write something as an answer to the question what you had given while in close ended questions you have given some options from where the participant has to select. As it is noted that most of the participants are interested towards the close ended questions. So if you want accuracy in your results and making your questionnaire effective than avoid open ended questions.
  • Write down research questions and focus group
  • Try to minimize number of questions