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Research Communication

Four-Day Multimedia Diet Records Underestimate Energy Needs in Middle-Aged and Elderly Women as Determined by Doubly-Labeled Water¹

School of Dietetics and Human Nutrition, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada

²To whom correspondence should be addressed.

	ABSTRACT

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Systematic problems exist in the quantification of food intake in populations using traditional self-reported measures. The objective of this study was to determine the effectiveness of an innovative multimedia diet record (MMDR) for dietary energy intake assessment. Dietary intake was estimated by combining the use of a microcassette tape recorder and 35-mm camera in 53 women whose ages ranged from 50 to 93 y (64.9 ± 11.3 y), with body weights of 62.4 ± 12.2 kg and body mass indexes (BMI) of 24.4 ± 4.0 kg/m². Using household measures, subjects voice-recorded and photographed all food and beverages consumed for four consecutive days. A two-point doubly-labeled water (DLW) method was used over 13 d to calculate carbon dioxide production, total body water, and subsequently, total energy expenditure (TEE) through the use of a food quotient. Mean body weight did not change between d 1 and 14. TEE and reported energy intake were compared using MMDR. Mean reported energy intakes 7.5 ± 1.9 MJ/d (1774 ± 476 kcal/d) were lower (P < 0.01) than TEE by 10.4 ± 3.1 MJ/d (2477 ± 736 kcal/d), indicating underreporting of food intake. Reporting accuracy (reported energy intake/TEE' 100%) was 76.0 ± 22.9%. Mean energy expenditure (MJ/d), as determined by doubly-labeled water, was higher (P < 0.01) in each stratified age range when compared to reported energy intake by MMDR. There were no significant differences in reporting accuracy among the stratified age groups. Using the MMDR method, this population of weight-stable women underreported their food intakes compared to their determined energy expenditure estimated by DLW.

KEY WORDS: • total energy expenditure • energy intake • doubly-labeled water • dietary assessment • humans

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Accuracy in dietary intake assessment is crucial for drawing associations between food intake, energy balance and disease incidence and in setting energy requirements for populations. However, self-reported intakes have been questioned due to the inconsistencies between estimations from recorded food intakes and energy expenditures determined by biological markers such as doubly-labeled water (DLW)³ or other methods of indirect calorimetry (Bingham et al. 1995 , Goran and Poehlman 1992 , Johnson et al. 1994 , Martin et al. 1996 ). Several methods exist for dietary intake assessment; however, since these are based on factual approaches using reported intakes, their validity is controversial. The reliability and validity of these methods hinge on subject compliance, interviewer skill, nutrient database appropriateness and quality of the training given to subjects for dietary reporting (Dwyer 1994 ).

The DLW technique is ideal for assessing energy expenditure because it is nonradioactive and noninvasive; thus, subjects can carry out their daily activities without being aware that they are being studied. In weight-stable individuals, energy expenditure must equal energy intake. This equilibrium provides a means of validating methods of assessing food intake. The purpose of the current study was to compare the energy intakes estimated from 4 d multimedia diet records (MMDR) using self-reported intakes with measured energy expenditures using DLW. A population sample of middle-aged and elderly Canadian women was used in this study. To facilitate the recording of food intake, a novel multimedia dietary assessment method was developed utilizing a tape recorder and camera in an attempt to more accurately quantify energy intake and improve upon traditional methods. It was expected that the MMDR would reduce subject burden and thus reduce the frequency of omission of food items from the MMDR, therefore, increasing the agreement between reported energy intake and measured expenditure in weight-stable individuals.

	MATERIALS AND METHODS

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A total of 73 women were recruited for the study from Montreal and surrounding areas by newspaper articles, radio and posted advertisements. The women either attended an introductory meeting regarding study participation or were recruited to participate by telephone. A medical screening questionnaire was completed by the study coordinator in person or by telephone regarding medical history. Subjects were also asked about their weight history in the previous 6 mo and any use of diuretics, appetite suppressants, nicotine, caffeine or alcohol. The study protocol excluded women who were taking >1 mg/d of thyroid hormone medication and whose weight had changed > 4 kg in the previous 6 mo. Prior to study commencement, the women were informed of study protocol and gave signed consent. The project was approved by the McGill University Ethics Committee.

The novel method of dietary intake assessment was developed by combining the use of a microcassette tape recorder and 35-mm camera. In an effort to ensure accurate and complete food records, the subjects were provided a training session prior to the study commencement. Subjects were supplied with standard household measurements, a ruler, a 35-mm camera and a microcassette tape recorder to measure and record all foods and beverages consumed and leftover for 4 d. Food habits differ on weekends and weekdays (Beaton 1994 ). Considering these day-to-day variations, the subjects were assigned a Wednesday-Saturday or Sunday-Wednesday recording period. Subjects recorded their intake from morning to bedtime on d 4–7 or 7–11 of the study period. Copies of recipes for homemade meals and labels from ready-to-eat preparations were requested, as well as specifications regarding the method of preparation and cooking. Subjects were asked not to alter their dietary patterns during the study period so that the MMDR would be typical of their usual dietary habits. Subjects who did not maintain a record for 4 d were excluded from the study. Food records were analyzed using Food Processor 5.0, ESHA (Portland, OR). When transposing taped records into written records, pictures were used for cross-referencing dietary intake reports to determine if foods in taped records and photographs corresponded, but were not used for quantification of energy intake.

To calculate total energy expenditure (TEE), a two-point DLW method was used. Baseline urine and saliva samples were collected and a dose of DLW was administered based on estimated body water (body weight x 50%) to the fasted subjects. The dose of 2.5 g H₂¹⁸O/kg [10% atom percentage excess (APE)] and 0.12 g D₂O/kg (99.9% APE) estimated body water was followed by a 50-mL rinse of fruit juice and a muffin. Subjects were asked to abstain from food and minimize water intake for 4 h and to collect a saliva sample for determination of body water at 3 and 4 h postdose. Subjects were given urine sample bottles to collect a second void sample at 24 h. On d 7, the women visited the study location and gave a second void urine sample and brought in the frozen samples previously collected. On d 14, fasting subjects returned to the study location and gave another second void urine sample and a saliva sample. A 200 g/L solution of D₂O (0.12 g/kg estimated body water) in tap water was taken orally and rinsed with 50 mL fruit juice. A muffin was again provided to break the fast. At 3 and 4 h postdose, subjects were instructed to provide saliva samples for a second estimate of body water. All collected samples were stored in parafilm-wrapped plastic containers and stored at -20°C.

Body composition was calculated using total body water (TBW) and weight on d 0 and 14 using isotope dilution of D₂O and H₂¹⁸O on d 0 and D₂O on d 14. TBW was calculated using the enrichment of saliva samples taken at 3 and 4 h postdose based on the assumption that fat-free mass (FFM) is 73.2% hydrated. (Pace and Rathburn 1945 ). Fat mass was calculated as the difference between body weight and FFM.

The isotopic analysis was conducted using standard vacuum techniques as previously described by Jones et al. (1988) . Urine and saliva samples containing D₂O were measured in duplicate or triplicate using a 903D dual-inlet isotope ratio mass spectrometer (IRMS), (VG Isogas, Cheshire, England). For H₂¹⁸O enrichment determination, 1.5-mL physiological samples of urine or saliva were added to Vacutainer tubes. Urine samples were analyzed for C¹⁸O₂ in three or four replicates as required using a SIRA 12 IRMS (VG Isogas). Carbon dioxide production was calculated using the equation:

(1)

The rate of CO₂ production is represented by R, TBW is determined based on d 1 or 14 (kg). The elimination rates of H₂¹⁸O and D₂O are designated by k_o and k_h, respectively. A standard respiratory quotient of 0.85 was used for all subjects to prevent bias due to inaccuracies in food recording.

Data are presented as means ± SD To compare anthropometric variables, TEE, and reporting accuracy with age, women were stratified into 49–59, 60–69, 70–79 and 80 + y age groups. Reporting accuracy was expressed as mean reported intake by MMDR in MJ/d divided by mean TEE/day x 100. Data were analyzed with the Student-Newman-Keuls test, and differences among age groups were considered significant when P < 0.05. The SAS statistical package was used (SAS Institute, Cary, NC).

	RESULTS

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Selected characteristics of the 53 subjects are presented by stratified age groups in Table 1 . Twenty subjects were excluded from the analyses. Seventeen subjects’ food records were excluded due to incompleteness or technical difficulties with the recording equipment. Two subjects’ analytical results suggested a higher turnover of hydrogen than oxygen. One subject’s analytical results suggested a TEE of 25.2 MJ/d (6022 kcal/d). This subject’s TEE was considered physiologically unlikely and was excluded from the analyses. There were no body weight changes between d 1 (62.9 ± 12.2 kg) and d 14 (62.8 ± 11.8 kg) or between TBW estimations for d 0 (30.4 ± 7.1 kg) and d 14 (29.6 ± 9.1 kg) by ²H₂ O analysis. The decay rates of H₂¹⁸O (k_o) and ²H₂O (k_h) for d 1 and 14 were 0.12 ± 0.03 and 0.09 ± 0.02 pools/d, respectively. Carbon dioxide production (rCO₂) was 11.3 ± 3.2 (mol/d).

Energy expenditure (MJ/d) as determined by DLW was significantly higher (P < 0.01) in each stratified age range when compared to reported energy intake by MMDR (Fig. 1 ). Women in the 50–59 y age range reported 8.2 ± 2.1 MJ/d (1954 ± 491 kcal/d); however, TEE was 11.5 ± 3.1 MJ/d (2759 ± 751 kcal/d), representing a reporting accuracy of 74.4 ± 22.7%. In the 60–69 y age group, reported intake was 7.7 ± 1.3 MJ/d (1780 ± 383 kcal/d) while TEE was determined to be 10.6 ± 3.0 MJ/d (2543 ± 712 kcal/d), which calculated to a reporting accuracy of 75.2 ± 17.4%. In the 70–79 y age group, reported intake was 7.2 ± 2.3 MJ/d (1724 ± 554 kcal/d) contrasting the TEE of 9.6 ± 2.8 MJ/d (2287 ± 677 kcal/d); reporting accuracy was 80.3 ± 33.3%. There were significantly reduced reported intakes and TEE in the 80 y + age group compared to the younger age groups, 5.5 ± 0.5 MJ/d (1313 ± 118 kcal/d) and 7.6 ± 1.7 MJ/d (1820 ± 417 kcal/d), respectively (P < 0.05), although these differences were not due to reporting accuracy (74.6 ± 15.2%), but more likely to reduced energy requirements. There were no differences in anthropometric measures across stratified age groups in body mass index (BMI) (23.5–25.2 kg/m²) or body weight (57.7–68.0 kg), although body fat percentage was significantly lower in the 60–69 y age group (21.2 ± 9.7%) compared to the group mean of (27.8 ± 11.1%), (P < 0.05).

View larger version (21K): [in this window] [in a new window]   Figure 1. Total energy expenditure (TEE) and energy intake assessed by multimedia diet records (MMDR) in women of various age groups. Bars indicate means + SEM, n are given in Table 1 . Uppercase letters depict significant differences (P < 0.05) in TEE derived from doubly-labeled water analyses among age groups while lowercase letters describe differences in MMDR analyses among age groups. MMDR values were calculated from a 4-d dietary assessment method using a tape recorder and camera.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

Measures of energy intake assessment using factual methods have innate problems due to their subjective nature. Factual methods depend on the assumption that the dietary data compiled are a valid and accurate assessment of intake and that subjects are in energy balance while the dietary information is obtained (Jones et al. 1997 ). Even a novel method of dietary intake recording used in this study resulted in subjects reporting only 76.0 ± 22.9% of their energy intake. There are several possible reasons for this underestimation. Since mean energy intake should equal mean intake in weight-stable subjects, the reported energy intake infers underestimation of intake or undereating in this population. There was no mean weight change over the 13 d DLW period; however, undereating for 4 d followed by overcompensation in energy intake for the next several days during the study period may have occurred. Subsequently, when the 4-d intake recording period ended, subjects may have returned to their normal eating patterns or even overcompensated for their temporary reduction in food intake while recording. Due to the relatively short intake recording period, it is difficult to establish whether a reduction in food intake during the reporting period or underreporting errors was the cause of the discrepancy between TEE and reported intake. In fact, both intake reduction and underreporting may have been jointly responsible. Some subjects may have underreported in an attempt to conform to socially acceptable food habits while others actually did conform, eliminating certain foods from their diet over the study period. Other researchers have reported negative relationships between reporting accuracy and TEE (Prentice et al. 1986 , Ravussin et al. 1982 , Schoeller 1988 , Welle et al. 1992 ) which is possibly indicative of reluctance to report all food intake.

Previous studies using self-reported food intakes compared to DLW show a consistent underestimation by participants and a wide variation in the energy intakes reported, depending on the method used (Bingham et al. 1995 , Goran and Poehlman 1992 , Johnson et al. 1994 , Martin et al. 1996 , Schoeller 1990 ). Rothenberg et al. (1998) compared diet histories in elderly Swedish subjects (n = 12) to DLW and found that they underestimated TEE by ~12% (8.62 ± 2.06 vs. 9.9 ± 1.43 MJ/d (2060 ± 492 vs. 2366 ± 341 kcal/d). Energy intakes calculated from 7 d of consecutive weighed food records, 24-h recalls and food frequency questionnaires were compared to DLW in middle-aged women (n = 28) by Martin et al. (1996) . TEE was 9.0 ± 2.1 MJ/d for subjects who were participating in a long-term dietary intervention study (48.5 ± 5.0 y, 61.8 ± 6.7 kg). Reporting accuracy was 79.8 ± 17.6% using 7-d weighed food records. The degree of underreporting was not associated with BMI, anthropometric measures, percentage of energy from fat or carbohydrate or length of time of the dietary trial. Reporting accuracy was similar in the present study at 76.0 ± 22.9%; however, neither method using 4-d MMDR or a conventional 7-d weighed record adequately estimated TEE. Johnson et al. (1994) examined correlates of reporting accuracy in older women (n = 56, 66 ± 6 y, 64.1 ± 7.6 kg) and found underreporting of -2.2 ± 1.8 ± MJ/d (526 ± 430 kcal) compared to TEE. In this group of normal weight women, TEE was 9.3 ± 1.0 MJ/d as measured by DLW in a subsample (n = 13) of the study population. Percentage body fat was negatively correlated with underreporting of intake (r = -0.42, P = 0.001). Pannemans and Westerterp (1993) examined a group of elderly volunteers (n = 12) using a 4-d food record and compared these reported intakes with expenditure determined using DLW. They concluded that food records underestimate energy expenditure and are inversely correlated with BMI. Results from the present study did not provide a correlation with BMI nor body fat percentage (data not shown).

The mean TEE in the present study closely approximated TEE found by Starling et al. (1998) who measured TEE using DLW (n = 51, 67 ± 6 y) and found TEE in women was 9.6 ± 2.7 MJ/d (2306 ± 647 kcal/d). In a subgroup of 70 women and men, the strongest predictors of TEE were resting metabolic rate (RMR) and VO_{2 peak} which explained ~62% of the variance in TEE. RMR accounted for 63% of TEE 6.1 ± 1.0 MJ/d (1463 ± 244 kcal/d). Energy expenditure due to physical activity was predicted most closely by (P < 0.05) VO_{2 peak} (r = 0.43), FFM (r = 0.39) and body weight (r = 0.34). These studies with similar mean energy expenditures offer validity to the mean TEE in the present study. The comparable rates of underreporting found in these studies also lend credence to the assumption that many subjects are either unwilling or unable to disclose all food intake.

MMDR were chosen because of the perceived reduction in subject burden when recording meals with a tape recorder as opposed to written records. The cross-referencing of tape-recorded diaries with photographs taken at the time of consumption was considered a method which could conceivably reduce the frequency rate of omissions. However, the methodology still relies on subject competence and willingness to record daily food intake. Bingham (1991) has suggested that 20% of subjects are either persistent underreporters or habitual dieters. She contends that whenever subjects are asked to keep a record of intake it is plausible that they will change their typical dietary habits to increase simplification of reporting or because they become cognizant of how much they really are consuming. The bias is typically toward underestimating intake due to many reasons including memory loss, a desire to conform to socially accepted food habits and simplification of reporting. Simplification of reporting may have been a factor in this study because some subjects were not confident with the use of a tape recorder and camera. Error could have occurred if there was an inclination to put off tape recording until the end of the day or 4 d recording period instead of as instructed, i.e., before every food item or beverage. Even though subjects were trained otherwise, several women indicated to the study coordinator at the end of the recording period that they had made written records and then taped their intake at the end of the day or after the 4-d period while taking pictures as instructed, i.e., before food consumption.

In conclusion, it is likely that the discrepancy between TEE and reported intake stemmed from a reduced intake in some subjects while others intentionally or inadvertently did not disclose all foods consumed. The TEE measurements are similar to those reported in other studies, leading to the conclusion that this multimedia approach to dietary recording failed to measure true intake. Other methods of dietary assessment should be encouraged to improve completeness of reporting food intake or to control for inherent errors in dietary intake assessment.

	FOOTNOTES

 
¹ Financial support for project research from the National Health Research and Development Program of Canada.

³ Abbreviations used: APE, atom percentage excess; BMI, body mass index; BMR, basal metabolic rate; DLW, doubly-labeled water; FFM, fat-free mass; IRMS, isotope ratio mass spectrometry; MMDR, multimedia diet record; TBW, total body water; TEE, total energy expenditure.

Manuscript received August 4, 1999. Revision accepted January 5, 2000.

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