Validation of dietary intakes measured by diet history against24 h urinary nitrogen excretion and energy expenditure measuredby the doubly-labelled water method in middle-aged women

Abstract

A diet history method for estimating energy and N intakes was validated against 24 h urinary N excretion and energy expenditure measured by the doubly-labelled water (DLW) method. Fortyeight women aged 50-65 years were studied over 1 year. Weighed diet records from 4 d and two 24 h urine collections, for measurement of urinary N excretion, were obtained in each of four seasons. At the end of the year, a diet history was obtained, BMR was measured by whole-body calorimetry, and, in sixteen women, total energy expenditure (EE) was measured by DLW. Energy intake (EI) and N intake (NI) were calculated using food tables. Using weighed records and diet history respectively mean NI were 11⋅21 (SD 2⋅09) g and 11⋅47 (SD 2⋅40) g (NS) and EI were 8⋅08 (SD 1⋅54) MJ and 8⋅20 (SD 1⋅86) MJ (NS). Mean urine N : NI and EI : BMR values indicated bias to under-reporting by weighed record and diet history techniques in some individuals, but there was no significant difference between these measures at the group level. The Pearson correlation coefficient (r) for urine N v. NI was 0⋅81 for the weighed record and 0⋅38 for the diet history. The correlation of EE v. EI was r 0⋅48 for weighed record and r 0⋅11 for diet history. In this study the diet history gave the same estimate of mean intake, but the weighed record appeared to perform better in ranking individuals. Diet history: Diet record: ValidationThe diet history method of assessing dietary intake is favoured for two reasons. First, as a retrospective questionnaire method, it places less burden on subjects than do prospective diet records. Second, it is believed to obtain a better measure of long-term habitual intake than diet records, which, of necessity, record intake on a limited number of days. The debate over the respective merits of the weighed diet record and the diet history is a long one and many studies over several decades have compared their relative validity. On balance the diet history tends to obtain higher mean energy intakes (EI) (see reviews by Bingham, 1987;Black et al. 1991). However, without external validation such studies have been unable to reach a firm conclusion as to which, if either, is valid in absolute terms.A valid dietary assessment should give an estimate of mean intake that is close to the true intake and also be able to rank individuals correctly for intake within acceptable limits of precision. The two requirements do not necessarily go together. For example, a dataset of valid 24 h recalls would give a valid estimate of mean intake but could not rank individuals correctly for habitual intake. A diet record of sufficient length to measure habitual intake might rank individuals correctly but give an invalid estimate of mean intake due to systematic bias across all subjects. If random errors are large and if systematic bias is variable across individuals, then ranking will also be poor. Studies of relative validity indicate whether one method gives a higher intake than another, and comparison with expected energy requirements can help determine ...

Assessment of habitual energy and macronutrient intake in adults: comparison of a seven day food record with a dietary history interview

“…In contrast with most (Jain et al, 1980;Hankin et al, 1991;Block et al, 1992;Jain et al, 1996;Black et al, 2000), but similar to other previous studies (Huenemann & Turner, 1942;Mahalko et al, 1985) we observed that the 7 day food record gave slightly higher nutrient estimates than the diet history interview. As compared to the more widely used structured interviews with specific questions on a large number of frequently consumed food, the traditional interview technique with non-leading and open-ended questions used in our study may tend to underestimate daily intake.…”

“…As compared to the more widely used structured interviews with specific questions on a large number of frequently consumed food, the traditional interview technique with non-leading and open-ended questions used in our study may tend to underestimate daily intake. However, as observed by others (Black et al, 2000), we found a close quantitatively agreement between the two methods and a small individual variation of the lack of agreement suggesting that for practical purposes the difference between methods in assessing energy and macronutrient intake is negligible. Figure 2 The between-method difference (diet history interview and 7 day food records) in assessment of total daily energy intake plotted against the average energy intake estimated from both methods with indication of the median difference and limits of agreement (BlandAltman plot).…”

Validation of protein intake assessed from weighed dietary records against protein estimated from 24 h urine samples in children, adolescents and young adults participating in the Dortmund Nutritional and Longitudinally Designed (DONALD) Study

“…Furthermore, the positive N balance of growing children and adolescents represents a specific methodological challenge. Therefore, our study took advantage of an ongoing longitudinal study, while validation studies in adults were mostly experimental and especially designed to assess validity (21)(22)(23) .…”

Influence of habitual diet on antioxidant status: a study in a population of vegetarians and omnivores

“…The method has previously been validated against 24-h urinary nitrogen excretion (Black et al, 2000) and is believed to place fewer burdens and obtain a better measure of long-term habitual intakes than diet records (Hankin, 1986). All diet histories were collected between the months of October and April to minimize effects of seasonal variations of dietary habits.…”