Validation of weighed records and other methods of dietary assessment using the 24 h urine nitrogen technique and other biological markers

Abstract

Results from analysis of 24 h urine collections, verified for completeness with para-amino benzoic acid, and blood samples collected over 1 year were compared with 16 d weighed records of all food consumed collected over the year, and with results from 24 h recalls, food-frequency questionnaires and estimated food records in 160 women. Using the weighed records, individuals were sorted into quintiles of the distribution of the urine N excreti0n:dietary N intake ratio (UN:DN). UN exceeded DN in the top quintile of this ratio; mean ratio UN:DN = 1.13. Individuals in this top quintile were heavier, had significantly greater body mass indices, were reportedly more restrained eaters, had significantly lower energy intake:basal metabolic rate ratios (EI:BMR), and had correlated ratios of UN:DN and EI : BMR (r -0.62). Those in the top quintile reported lower intakes of energy and energy-yielding nutrients, Ca, fats, cakes, breakfast cereals, milk and sugars than individuals in the other quintiles but not lower intakes of non-starch polysaccharides, vitamin C, vegetables, potatoes or meat. Correlations between dietary intake from weighed records and 24 h urine K were 0.74 and 0.82, and between dietary vitamin C and &carotene and plasma vitamin C and &carotene 0.86 and 0.48. Correlations between dietary N intake from weighed records and 24 h urine excretion were high (0-78-0.87). Those between N from estimated food records and urine N were r 0-60-0.70. Correlations between urine N and 24 h recalls and food-frequency questionnaires were in the order of 0.01 to 0.5. Despite problems of underreporting in overweight individuals in 20% of this sample, weighed records remained the most accurate method of dietary assessment, and only an estimated 7 d diary was able to approach this accuracy. Dietary assessment methods: Urine nitrogen: Dietary nitrogenThe validity of measurements of dietary intake in free-living individuals is difficult to assess because all methods rely on information given by the subjects themselves, which may not be correct. In an attempt to determine objective measures for validating dietary assessments, the search has begun for analytes of biological specimens that closely reflect dietary intake, but which do not rely on reports of food consumption (Isaksson, 1980;Bingham, 1987). In individuals in energy and N balance, urine N as assessed from 8 d of complete 24 h urine available at https://www.cambridge.org/core/terms. https://doi

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

“…Urinary 24 h N excretion (2 d in each of the four seasons, eight collections in total) was also measured. These data were obtained in a study to determine the best dietary assessment method to use in the European Prospective Investigation into Cancer (Bingham et al 1994(Bingham et al , 1995 conducted between 1989 and 1990. The present study additionally assessed EI and NI in the fourth season by diet history and, in sixteen subjects, measured EE by DLW and BMR by whole-body calorimetry.…”

“…Urine collections (24 h) were made using boric acid as a preservative in the collection container (Bingham et al 1995). In each season, two 24 h urine collections were obtained, one during the 4 d period of diet records and one in the 2 d immediately following.…”

“…The earliest validations of the diet history method by urinary N excretion (Steen et al 1977;Bingham et al 1982;van Staveren et al 1985;Hultén et al 1990) did not include validation for completeness of the 24 h urine collections by the PABACHEK method (Bingham & Cummings, 1983) which uses p-amino benzoic acid (PABA) as a marker. It is known that a substantial proportion of collections may be incomplete; Heitmann (1993) rejected 17 %, Bingham et al (1995) 25 %, and SD Poppitt, G Keogh and AA Black (personal communication) 40 %. The ratio urine N : N intake (NI) is used as the estimate of validity and incomplete collection produces a bias towards showing the reported intake to be valid.…”

Eating patterns and dietary composition in relation to BMI in younger and older adults

“…23,24 This under-reporting, primarily by overweight and obese persons, may be specific to energy-dense snack and dessert-type foods. [25][26][27][28] We recently reported that implausible energy intakes affect apparent eating patterns as well, being associated with lower reported meal and snack frequencies, energy densities and portions consumed. 9,10,22 With aging comes a decline in the ability to regulate food intake.…”

Comparison of three methods for estimating daily individual discretionary salt intake: 24 hour recall, duplicate-portion method, and urinary lithium-labelled household salt excretion

“…Duplicate portion techniques are well established for assessing total nutrient intake and are considered to be one of the most accurate methods available for assessing habitual dietary intake (Bingham et al, 1995). The method has been used to assess the intake of sodium and a number of trace elements (Clark & Mossholder, 1986;Anderson et al, 1993).…”