Dietary Assessment Methods - Essay Example

? Dietary Assessment Methods School Introduction Researchers, physicians and nutritionists commonly use a variety of dietary assessment methods in order to identify, monitor and/or examine an individual or group's dietary practices and behaviors. While dietary assessment methods can be useful tools, none of the methods provide data that is one hundred percent accurate (Kristal, Andrilla, Koepseli, Diehr & Cheadle, 1998: Kubena, 2000). In methods that are self-reported, for example, certain respondent-related factors cause reporting errors, such as memory lapse, fatigue and unfaithful or incorrect reporting (Kubena, 2000). Sociodemographic, ethnic and cultural factors have also been found to influence responses (e.g. gender, age, weight or body mass index, level of education, ethnicity, cultural background) (Buzzard & Sievert, 1994; Johansson, Wikman, Ahren, Hallmans & Johansson, 2001; Paalanen et al., 2006). Since no dietary assessment method provides results that are totally error-free, it is important to select the method that is most appropriate for the intended use, as each method has its own strengths and weaknesses (Fernandez-Balart et al., 2010; Kubena, 2000). The food frequency questionnaire and the food diary/record are two commonly used dietary assessment methods. This paper will examine each method and then compare/contrast the two. Food Frequency Questionnaire Currently, the food frequency questionnaire (FFQ) is the most commonly used method in large epidemiological and clinical research studies (Jardack, 2006). The questionnaire contains a list of foods and respondents are asked how frequently they consumed those foods over a certain time period (Buzzard & Sievert, 1994; Watson, Collins, Sibbritt, Dibley & Garg, 2009). Responses can be self-reported by participants or be given in a short interview. A FFQ may or may not contain information regarding portion size - FFQs with no portion size information provide quantitative data; FFQs with portion size information based on current standards provide semi-qualitative data; and, FFQs using portion size information reported by the respondents provide qualitative data (Fernandez-Balart et al., 2010). The FFQ has repeatedly been found to have a high percentage of agreement between record and recall, supporting its reliability as a dietary assessment tool (Block, 1982; Fernandez-Balart et al., 2010; Paalanen et al., 2006). Furthermore, compared to other dietary assessment methods, the FFQ is relatively inexpensive to administer, quick to complete and imposes a low burden on respondents, supporting its suitability for use with large populations (Block, 1982; Kubena, 2000). A number of studies have found the FFQ to be a reliable and valid tool, especially for use with large populations; however, the FFQ is not without its limitations (Block, 1982; Fernandez-Balart et al., 2010; Paalanen et al., 2006). For example, the validity of the FFQ has been shown to improve with the use of a more detailed food list that is designed to be appropriate for use with a specific population; therefore, FFQs must contain food lists specifically designed for the population that is intended to provide the responses (Watson et al., 2009). As with all dietary assessment methods, another limitation of the FFQ is that the data collected is subject to respondent error, which may be caused by a number of factors (e.g. memory lapse, fatigue, unfaithful or incorrect reporting, sociodemographic, ethnic, cultural)(Buzzard & Sievert, 1994; Johansson et al., 2001). Finally, another weakness of the FFQ is that dietary intake is often overestimated by respondents, especially on the first administration; however, estimated intake values decrease and more accurate responses are provided in subsequent administrations of the FFQ (Fernandez-Balart et al., 2010). Food Diary/Record Another widely used dietary assessment method is the food diary or food record (FR). The FR requires participants to record their actual food intake at the time the food is eaten. This method of dietary assessment has been found to provide the most accurate reporting of dietary intake; in fact, it is often considered the “gold standard” with regard to reporting accuracy (Block, 1982). Participants report food intake at the time they are actually eating resulting in reports that are usually more precise and accurate than those from other dietary assessment methods. The duration of the FR can be adjusted to meet the specific needs of each situation; and, its validity has been found to increase as days of recording increase (Id.). However, like all dietary assessment methods, the FR has limitations, the most significant being that it is expensive, time-consuming and burdensome for both respondents and researchers (Id.). In addition to the limitations common to all dietary assessment methods (e.g. inaccurate or errors in reporting, effects of sociodemographic, ethnic and cultural factors), a significant limitation of the FR is that it is highly burdensome on both researcher and respondent and it is expensive and time-consuming to administer (Block, 1982; Buzzard & Sievert, 1994; Paalanen et al., 2006). Respondents must be literate and have the ability to legibly and accurately record descriptions of foods and food quantities in order to properly comply with the requirements of the FR. Therefore, it is not a suitable dietary assessment method for all situations; for example, the FR would not be an appropriate method to use with very young children. Furthermore, participants must be willing and able to take the time needed to complete the FR since recording every instance of food intake at the actual time of eating can be, and usually is, very time-consuming (Block, 1982). FFQ vs. FR Both the FFQ and FR are acceptable and widely used, but very different, dietary assessment methods. For example, the FFQ assesses dietary behaviors retrospectively (i.e. relies on memory), while the FR assesses dietary behaviors prospectively (i.e. focuses on current diet); and, the FFQ only requires respondents to complete a questionnaire, while the FR requires the recording of all food intake by respondents (Block, 1982; Buzzard & Sievert, 1994; Jardack, 2006). The low cost, small amount of time and minimal respondent and researcher burden needed to administer the FFQ make it well suited for use with large populations (Kubena, 2000). On the other hand, the FR is better suited for use with individuals or small groups since administration is expensive, time-consuming and imposes a heavy burden on both respondent and researcher (Fernandez-Balart et al., 2010; Jardack, 2006). Even though the FFQ and FR are very different methods of dietary assessment, they also have some similarities which are basically found in all of the current dietary assessment methods. One of these similarities is that both methods are subject to errors in reporting; however, the FFQ, just because of its design, is obviously more susceptible to reporting errors than the FR. Another similarity between the FFQ and FR is that their reliability and validity as dietary assessment methods is influenced by sociodemographic, ethnic and cultural factors (Johansson et al., 2001; Paalanen et al., 2006). Respondent related errors (e.g. fatigue, unfaithful or incorrect reporting) also affect reporting accuracy in both the FFQ and FR (Buzzard & Sievert, 1994; Johansson et al., 2001). Conclusion Dietary assessment methods are useful tools used to examine dietary behaviors; however, none of the current methods provides results that are totally error-free (Kristal et al., 1998). Each method has its own strengths and weaknesses and is better suited for different intended purposes with different populations. Even though the FFQ and FR have similarities, they are actually very different dietary assessment methods. This examination of the FFQ and FR show that it is essential to choose the dietary assessment method that most appropriate and best suited for its intended purpose with the intended target population (Johansson et al., 2001; Kristal et al., 1998). References Block, G. (1982). A review of validations of dietary assessment methods. American Journal of Epidemiology, 115(4), 492-505. Buzzard, I.M. & Sievert, Y.A. (1994). Research priorities and recommendations for dietary assessment methodology. American Journal of Clinical Nursing, 59(suppl.), 275S-280S. Fernandez-Balart, J.D. et al. (2010). Relative validity of a semi-quantitative food frequency questionnaire in an elderly Mediterranean population of Spain. British Journal of Nutrition, 103, 1808-1816. Jardack, P.M. (2006). Dietary intake measurement: cues to improve accuracy. Journal of the American Dietetic Association, 108(8), 1217-1218. Johansson, G., Wikman, A., Ahren, A., Hallmans, G. & Johansson, I. (2001). Underreporting of energy intake in repeated 24-hour recalls related to gender, age, weight status, day of interview, educational level, reported food intake, smoking habits and area of living. Public Health Nutrition, 4(4), 919-927. Kristal, A.R., Andrilla, H.A., Koepseli, T.D., Diehr, P.H. & Cheadle, A. (1998). Dietary assessment instruments are susceptible to intervention-associated response set bias. Journal of the American Dietetic Association, 98(1), 40-44. Kubena, K.S. (2000). Accuracy in dietary assessment: on the road to good science. Journal of the American Dietetic Association, 100(7), 775-776. Paalanen, L. et al. (2006). Validity of a food frequency questionnaire varied by age and body mass index. Journal of Clinical Epidemiology, 59, 994-1001. Watson, J.F., Collins, C.E., Sibbritt, D.W., Dibley, M.J. & Garg, M.L. (2009). Reproducibility and comparative validity of a food frequency questionnaire for Australian children and adolescents. 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