On the other hand, the intervention focus may actually increase underreporting, due to demand characteristics. 16, 33 Perhaps the focus on nutrition (and several dietary assessments) in a nutrition intervention reduces the prevalence of underreporting. 32 Additionally, there have been calls to determine if dietary interventions per se either increase or decrease the prevalence of underreporting. If the error is nonrandom, this poses a much more difficult methodological challenge. 13, 31 That is, are the same individuals underreporting consistently over time or is this bias a random phenomenon? If the bias is random, this error can potentially be overcome using larger sample sizes. For example, what is the prevalence of dietary underreporting in the same cohort over time? Does underreporting increase or decrease over time? An important methodologic issue is whether dietary underreporting is a systematic bias or random error. Several issues are crucial for understanding the utility and accuracy of dietary assessment. 8 Predictors of dietary underreporting in children have not been well elucidated, but similar to adults, overweight status and increasing age appear to be the strongest and most consistent predictors. 25 However, despite the aforementioned, the majority of investigations of dietary misreporting have studied predominantly white children and adolescents, and relatively few studies have explored racial and/or gender differences. These investigators also found “drive for thinness” and BMI associated with underreporting in black participants but not in whites. found most black women and almost all white women in their late teens underreported their dietary intake. 24 In a biracial cohort of adolescents and young adults, Kimm et al. 23 Champagne and colleagues found significant dietary underreporting when comparing 8-day food records to doubly-labeled water, with African-American children more likely to underreport (37%) than white children (13%). Estimates of underreporting vary significantly, ranging from 4.9% in a large French cohort of children and preadolescents 22 to 49% in a sample of over 600 predominantly Mexican-American children. However, less is known about the prevalence and predictors of dietary underreporting in children and adolescents. 18– 20 That is, overweight and obese adults are at highest risk of dietary underreporting. 14– 17 Predictors of dietary underreporting include age, socioeconomic status, and weight status, with the most consistent and strongest predictor being BMI. Estimates in the adult population range from 27% to 65%. 10– 13 In adults, several studies using different methodologies have consistently found underreporting. Regardless of which method of dietary intake is used, there is strong evidence that dietary underreporting is very common. 8 Johnson recommends a minimum of 3 nonconsecutive days of dietary recall consisting of at least one weekend day for adults. Although these three approaches to collecting dietary intake data have their strengths and weaknesses in terms of accuracy and feasibility, several studies have reported that the method of multiple dietary recalls on nonconsecutive days is the preferred and most reproducible method of dietary assessment in children. There are three primary methods of assessing dietary intake in clinical trials and epidemiologic studies: Dietary records, food frequency questionnaires, and dietary recalls. In clinical trials of obesity prevention and treatment, evaluation of dietary intake, along with body weight and assessment of activity is often an important end point. 4, 5 Accurate assessment of dietary intake is necessary to identify dietary excesses and deficiencies and recommend appropriate interventions. 1, 2 Using dietary assessments, the literature supports the association of an unhealthy diet with three of the leading causes of adult deaths in the United States ( i.e., coronary artery disease, cancer, and stroke), a number of preventable chronic diseases and disorders, 3 and, more recently, the rapidly increasing prevalence of obesity and type II diabetes in children and adolescents. The assessment of dietary intake is essential for monitoring nutritional status, as well as for conducting epidemiological and clinical research regarding the association between diet and health.
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