Diet Quality among Pre-Adolescent African American Girls in a Randomized Controlled Obesity Prevention Intervention Trial.

Consuming an unhealthy diet increases health risks. This study assessed the impact of a culturally adapted behaviorally innovative obesity prevention intervention (The Butterfly Girls and the Quest for Founder's Rock) on diet quality in pre-adolescent non-Hispanic Black/African American girls. The RCT consisted of three groups (experimental, comparison, and waitlist control); block randomization allocated participants to each group. The two treatment groups varied in terms of whether or not they set goals. Data were collected at baseline (prior to receiving the intervention), post 1 (3 months post-baseline), and post 2 (6 months post-baseline). Two dietitian-assisted 24 h dietary recalls were collected at each timepoint. Healthy Eating Index 2015 (HEI-2015) was used to determine diet quality. A total of 361 families were recruited; 342 completed baseline data collection. No significant differences in overall HEI score or component scores were observed. To attain more equitable health outcomes, future efforts to promote dietary intake change among at-risk children should explore other behavior change procedures and employ more child-friendly dietary assessment methods.

Validity of a Digital Diet Estimation Method for Use with Preschool Children.

BACKGROUND: The validity of using the Remote Food Photography Method (RFPM) for measuring food intake of minority preschool children's intake is not well documented. OBJECTIVE: Our aim was to determine the validity of intake estimations made by human raters using the RFPM compared with those obtained by weighing all foods and beverages consumed by 3- to 5-year-old children (weighed method). DESIGN: We conducted a cross-sectional observational study. PARTICIPANTS/SETTINGS: A convenience sample of 54 3- to 5-year-old Hispanic and African-American children were observed during a 12-hour period at Baylor Metabolic Research Unit between June 2013 and January 2014. MAIN OUTCOME MEASURES: All foods/beverages consumed by the children were provided by Baylor research coordinators who took and wirelessly transmitted before-and-after pictures of the trays to trained human raters at the Pennington Biomedical Research Center who estimated grams consumed. Energy and macronutrients were calculated using the Food and Nutrient Database for Dietary Studies or food facts data provided by manufacturers. STATISTICAL ANALYSES: Paired t test, mean differences, and Bland-Altman limits of agreement were performed. RESULTS: Compared to the weighed method, the rater method significantly overestimated total intake by 34±71 g (P<0.0001), with a mean percent error of 2.9% (root mean square error=7.1%), and total energy intake by 75±102 kcal (P<0.0001), with a mean percent error of 7.5% (root mean square error=12.3%). The standard error for the macronutrient intakes ranged from 11.0% to 20.2%. The Bland-Altman approach demonstrated a positive slope for the rater method relative to the weighed method for total intake in grams (P=0.006), carbohydrate (P=0.01), and protein (P=0.01) (ie, magnitude of the bias increased with increasing intakes). CONCLUSIONS: The rater method overestimated total intake in grams and energy in kilocalories in minority preschool children in a well-controlled condition and needs to be further tested in a free-living environment.

Validity of the Remote Food Photography Method Against Doubly Labeled Water Among Minority Preschoolers.

OBJECTIVE: The aim of this study was to determine the validity of energy intake (EI) estimations made using the remote food photography method (RFPM) compared to the doubly labeled water (DLW) method in minority preschool children in a free-living environment. METHODS: Seven days of food intake and spot urine samples excluding first void collections for DLW analysis were obtained on thirty-nine 3- to 5-year-old Hispanic and African American children. Using an iPhone, caregivers captured before and after pictures of each child's intake, pictures were wirelessly transmitted to trained raters who estimated portion size using existing visual estimation procedures, and energy and macronutrients were calculated. Paired t tests, mean differences, and Bland-Altman limits of agreement were performed. RESULTS: The mean EI was 1,191 ± 256 kcal/d using the RFPM and 1,412 ± 220 kcal/d using the DLW method, resulting in a mean underestimate of 222 kcal/d (-15.6%; P < 0.0001) that was consistent regardless of intake. The RFPM underestimated EI by -28.5% in 34 children and overestimated EI by 15.6% in 5 children. CONCLUSIONS: The RFPM underestimated total EI when compared to the DLW method among preschoolers. Further refinement of the RFPM is needed for assessing the EI of young children.

Removing Potatoes from Children's Diets May Compromise Potassium Intake.

White potatoes are a forgotten source of nutrients. The goal of this study was to identify the nutritional implications of replacing a composite of white potatoes with a composite of vegetables commonly consumed by children aged 2-18 y (n = 3460) in a nationally representative sample. The NHANES 2005-2012 24-h dietary recall data were used to determine nutrient intake. Two replacement models were developed: one for potato consumers and another for those consuming vegetables other than potatoes. Analyses focused on 1) mean nutrient contributions per 1 cup equivalent vegetable composite (VC)/potato composite (PC) consumed by participants, and 2) mean daily nutrient intake when the nutrients per 1 cup equivalent PC replaced the nutrients per 1 cup equivalent VC. Covariate adjusted analysis was tested for statistical significance (P < 0.002). When 1 cup equivalent VC replaced 1 cup equivalent PC, significantly lower mean intakes were found for 20 of the 23 nutrients studied and higher mean intakes of total sugars, folate, and calcium. Differences were found including higher total intakes of monounsaturated fatty acids and potassium and lower total intakes of vitamins A and K. The percentage contribution of the PC to total daily nutrient intake was 6% for total energy, 8% for total fat, 5% for saturated fatty acids, 13% for dietary fiber, 4% for sodium, and 11% for potassium. Both composites contributed a variety of nutrients to the total diet; the consumption of white potatoes may be an important strategy to help meet the potassium recommendation.

Simulated adaptations to an adult dietary self-report tool to accommodate children: impact on nutrient estimates.

OBJECTIVE: To simulate the effect of child-friendly (CF) adaptations of the National Cancer Institute's Automated Self-Administered 24-Hour Dietary Recall (ASA24) on estimates of nutrient intake. METHOD: One hundred twenty children, 8-13 years old, entered their previous day's intake using the ASA24 and completed an interviewer-administered recall using the Nutrition Data System for Research (NDSR). Based on a hypothesis that proposed adaptations to the ASA24 will not significantly affect mean nutrient estimates, ASA24 data were manipulated postadministration to simulate a CF version in which 2 categories of data collection were removed: (1) foods not likely to be consumed by children (45%) based on previous analyses of national dietary data and (2) food detail questions (probes) to which children are unlikely to know the answers (46%), based on our experience. RESULTS: Mean estimates of select nutrients between the beta version of ASA24 and the simulated CF recall showed no significant differences, indicating that the food and probe elimination did not significantly affect results. However, a comparison of total sugar and vitamin C assessments between the original ASA24, the CF version, and NDSR showed that the daily nutrient totals for both nutrients were significantly higher in the self-administered methods (both ASA24 and CF version) than in NDSR (interviewer-administered), which warrants a review of different methods for obtaining information about foods that are sources of these nutrients. CONCLUSION: The simulation of CF adaptations showed that it is feasible to implement, thereby reducing CF response burden without significantly affecting the results.

Comparison of a Web-based versus traditional diet recall among children.

Self-administered instruments offer a low-cost diet assessment method for use in adult and pediatric populations. This study tested whether 8- to 13-year-old children could complete an early version of the Automated Self Administered 24-hour diet recall (ASA24) and how this compared to an interviewer-administered 24-hour diet recall. One-hundred twenty 8- to 13-year-old children were recruited in Houston from June through August 2009 and randomly assigned to complete either the ASA24 or an interviewer-administered 24-hour diet recall, followed by the other recall mode covering the same time interval. Multivariate analysis of variance, testing for differences by age, sex, and ethnic/racial group, were applied to percentages of food matches, intrusions, and omissions between reports on the ASA24 and the interviewer-administered 24-hour diet recall. For the ASA24, qualitative findings were reported regarding ease of use. Overall matches between interviewer-administered and ASA24 self-administered 24-hour diet recall was 47.8%. Matches were significantly lower among younger (8- to 9-year-old) compared with older (10- to 13-year-old) children. Omissions on ASA24 (18.9% overall) were most common among 8-year-olds and intermediate among 9-year-olds. Eight- and 9-year-olds had substantial difficulties and often required aid in completing ASA24. Findings from this study suggest that a simpler version of an Internet-based diet recall program would be easier for children to use.

6-n-propylthiouracil taster status not related to reported cruciferous vegetable intake among ethnically diverse children.

Sensitivity to the taste of 6-n-propylthiouracil (PROP) (a bitter chemical related to the phenylthiocarbamide found in cruciferous vegetables) has been related to dietary intake or preferences of cruciferous vegetables among adults and young children but not middle-aged children or adolescents. We hypothesized that PROP taste sensitivity is related to lower reported dietary intake of cruciferous vegetables, primarily among younger children (ie, a moderating effect of child age). This study examined the relationship of PROP sensitivity to reported dietary intake across 3 days in 2 age groups of youth (9-10 and 17-18 years) while statistically controlling for physical activity, social desirability, and reporting bias. Cross-sectional design was used with a multiethnic (white, African American, Hispanic, etc) sample of 843 men and women. Children were recruited from and data were collected in local elementary and high schools that had at least 30% ethnic minority enrollment. Children providing nonplausible reports of dietary intake were deleted from the analyses. Body mass index was calculated and expressed in z scores. Energy intake and physical activity were measured by 3 telephone-conducted 24-hour dietary recalls with the Nutrient Data System for Research and 5 days of Actigraph (ActiGraph, Shalimar, Florida) activity monitor. The primary analyses included 347 students. 6-n-Propylthiouracil sensitivity was not related to intake of cruciferous vegetables. Intakes of the cruciferous vegetables were low, which may explain the lack of relationship.

Children's accuracy of portion size estimation using digital food images: effects of interface design and size of image on computer screen.

OBJECTIVE: To test the effect of image size and presence of size cues on the accuracy of portion size estimation by children. DESIGN: Children were randomly assigned to seeing images with or without food size cues (utensils and checked tablecloth) and were presented with sixteen food models (foods commonly eaten by children) in varying portion sizes, one at a time. They estimated each food model's portion size by selecting a digital food image. The same food images were presented in two ways: (i) as small, graduated portion size images all on one screen or (ii) by scrolling across large, graduated portion size images, one per sequential screen. SETTING: Laboratory-based with computer and food models. SUBJECTS: Volunteer multi-ethnic sample of 120 children, equally distributed by gender and ages (8 to 13 years) in 2008-2009. RESULTS: Average percentage of correctly classified foods was 60·3 %. There were no differences in accuracy by any design factor or demographic characteristic. Multiple small pictures on the screen at once took half the time to estimate portion size compared with scrolling through large pictures. Larger pictures had more overestimation of size. CONCLUSIONS: Multiple images of successively larger portion sizes of a food on one computer screen facilitated quicker portion size responses with no decrease in accuracy. This is the method of choice for portion size estimation on a computer.

Video game play, child diet, and physical activity behavior change a randomized clinical trial.

BACKGROUND: Video games designed to promote behavior change are a promising venue to enable children to learn healthier behaviors. PURPOSE: Evaluate outcome from playing "Escape from Diab" (Diab) and "Nanoswarm: Invasion from Inner Space" (Nano) video games on children's diet, physical activity, and adiposity. DESIGN: Two-group RCT; assessments occurred at baseline, immediately after Diab, immediately after Nano, and 2 months later. Data were collected in 2008-2009, and analyses were conducted in 2009-2010. SETTING/PARTICIPANTS: 133 children aged 10-12 years, initially between 50th percentile and 95th percentile BMI. INTERVENTION: Treatment group played Diab and Nano in sequence. Control Group played diet and physical activity knowledge-based games on popular websites. MAIN OUTCOME MEASURES: Servings of fruit, vegetable, and water; minutes of moderate to vigorous physical activity. At each point of assessment: 3 nonconsecutive days of 24-hour dietary recalls; 5 consecutive days of physical activity using accelerometers; and assessment of height, weight, waist circumference, and triceps skinfold. RESULTS: A repeated measures ANCOVA was conducted (analyzed in 2009-2010). Children playing these video games increased fruit and vegetable consumption by about 0.67 servings per day (p<0.018) but not water and moderate-to-vigorous physical activity, or body composition. CONCLUSIONS: Playing Diab and Nano resulted in an increase in fruit and vegetable intake. Research is needed on the optimal design of video game components to maximize change.

Assessment of the accuracy of portion size reports using computer-based food photographs aids in the development of an automated self-administered 24-hour recall.

OBJECTIVE: To assess the accuracy of portion-size estimates and participant preferences using various presentations of digital images. DESIGN: Two observational feeding studies were conducted. In both, each participant selected and consumed foods for breakfast and lunch, buffet style, serving themselves portions of nine foods representing five forms (eg, amorphous, pieces). Serving containers were weighed unobtrusively before and after selection as was plate waste. The next day, participants used a computer software program to select photographs representing portion sizes of foods consumed the previous day. Preference information was also collected. In Study 1 (n=29), participants were presented with four different types of images (aerial photographs, angled photographs, images of mounds, and household measures) and two types of screen presentations (simultaneous images vs an empty plate that filled with images of food portions when clicked). In Study 2 (n=20), images were presented in two ways that varied by size (large vs small) and number (4 vs 8). SUBJECTS/SETTING: Convenience sample of volunteers of varying background in an office setting. STATISTICAL ANALYSES PERFORMED: Repeated-measures analysis of variance of absolute differences between actual and reported portions sizes by presentation methods. RESULTS: Accuracy results were largely not statistically significant, indicating that no one image type was most accurate. Accuracy results indicated the use of eight vs four images was more accurate. Strong participant preferences supported presenting simultaneous vs sequential images. CONCLUSIONS: These findings support the use of aerial photographs in the automated self-administered 24-hour recall. For some food forms, images of mounds or household measures are as accurate as images of food and, therefore, are a cost-effective alternative to photographs of foods.

Tests of the accuracy and speed of categorizing foods into child vs professional categories using two methods of browsing with children.

This research tested whether children could categorize foods more accurately and speedily when presented with child-generated rather than professionally generated food categories, and whether a graphically appealing browse procedure similar to the Apple iTunes (Cupertino, CA) "cover flow" graphical user interface accomplished this better than the more common tree-view structure. In Fall 2008, 104 multiethnic children ages 8 to 13 were recruited at the Baylor College of Medicine (Houston, TX) and randomly assigned to two browse procedures: cover flow (collages of foods in a category) or tree view (food categories in a list). Within each browse condition children categorized the same randomly ordered 26 diverse foods to both child and professionally organized categories (with method randomly sequenced per child). Acceptance of categorization was determined by registered dietitians. Speed of categorization was recorded by the computer. Differences between methods were determined by repeated measures analysis of variance. Younger children (8 to 9 years old) tended to have lower acceptance and longer speeds of categorization. The quickest categorization was obtained with child categories in a tree structure. Computerized dietary reporting by children can use child-generated food categories and tree structures to organize foods for browsing in a hierarchically organized structure to enhance speed of categorization, but not accuracy. A computerized recall may not be appropriate for children 9 years of age or younger.

Fruit and vegetables are similarly categorised by 8-13-year-old children.

OBJECTIVE: This exploratory study assessed how 8-13-year-old children categorised and labelled fruit and vegetables (FaV), and how these were influenced by child characteristics, to specify second-level categories in a hierarchical food search system for a computerised 24 h dietary recall (hdr). DESIGN: Two sets of food cards, sixty-seven for fruit (F) and sixty-four for vegetables (V), with pictures and names of FaV from ten professionally defined food categories were sorted, separately, by each child into piles of similar foods. Demographic data, BMI and 6-n-propylthiouracil (PROP) taster status were obtained. SETTING: Participants attended the Children's Nutrition Research Center in the summer of 2006. SUBJECTS: In all, 152 8-13-year-old children, predominantly English-speaking, of whom sixteen were predominantly Spanish-speaking. RESULTS: Children created an average of 8.5 (5.3) piles with 7.9 (11.4) cards per pile for the F, and an average of 10.1 (4.8) piles with 6.2 (7.9) cards per pile for the V. No substantial differences in Robinson clustering were detected across subcategories for each of the demographic characteristics, BMI or PROP sensitivity. Children provided clusters names that were mostly 'Taxonomic - Professional' labels, such as salads, berries, peppers, for both F (51.8 %) and V (52.1 %). CONCLUSIONS: These categories should be tested to assess their ability to facilitate search of FaV items in a computerised 24 hdr for children in this age group.

Challenges in converting an interviewer-administered food probe database to self-administration in the National Cancer Institute Automated Self-administered 24-Hour Recall (ASA24).

The National Cancer Institute (NCI) is developing an automated, self-administered 24-hour dietary recall (ASA24) application to collect and code dietary intake data. The goal of the ASA24 development is to create a web-based dietary interview based on the US Department of Agriculture (USDA) Automated Multiple Pass Method (AMPM) instrument currently used in the National Health and Nutrition Examination Survey (NHANES). The ASA24 food list, detail probes, and portion probes were drawn from the AMPM instrument; portion-size pictures from Baylor College of Medicine's Food Intake Recording Software System (FIRSSt) were added; and the food code/portion code assignments were linked to the USDA Food and Nutrient Database for Dietary Studies (FNDDS). The requirements that the interview be self-administered and fully auto-coded presented several challenges as the AMPM probes and responses were linked with the FNDDS food codes and portion pictures. This linking was accomplished through a "food pathway," or the sequence of steps that leads from a respondent's initial food selection, through the AMPM probes and portion pictures, to the point at which a food code and gram weight portion size are assigned. The ASA24 interview database that accomplishes this contains more than 1,100 food probes and more than 2 million food pathways and will include about 10,000 pictures of individual foods depicting up to 8 portion sizes per food. The ASA24 will make the administration of multiple days of recalls in large-scale studies economical and feasible.

Grains are similarly categorized by 8- to 13-year-old children.

This study assessed how 8- to 13-year-old children categorized and labeled grain foods and how these categories and labels were influenced by child characteristics. The main hypotheses were that children categorized foods in consistent ways and these food categories differed from the professional food categories. A set of 71 cards with pictures and names of grain foods from eight professionally defined food groups was sorted by each child into piles of similar foods. There were 149 8- to 13-year-old children (133 English-speaking, 16 Spanish-speaking) in this exploratory study. One-way analysis of variance and Robinson matrices for identification of clusters of food items were calculated. Children created a mean (+/-standard deviation) of 8.3+/-3.8 piles with 8.6+/-9.1 cards per pile. No substantial differences in Robinson clustering were detected across subcategories for each of the demographic characteristics. For the majority of the piles, children provided "taxonomic-professional" (34.5%) labels, such as bread for the professional category of breads, rolls, and tortillas, or "script" (26.1%) labels, such as breakfast for the professional category of pancakes, waffles, and flapjacks. These categories may be used to facilitate food search in a computerized 24-hour dietary recall for children in this age group.

Diverse food items are similarly categorized by 8- to 13-year-old children.

OBJECTIVE: Assess how 8- to 13-year-old children categorized and labeled food items for possible use as part of a food search strategy in a computerized 24-hour dietary recall. DESIGN: A set of 62 cards with pictures and names of food items from 18 professionally defined food groups was sorted by each child into piles of similar food items. SETTING: Participants attended the Children's Nutrition Research Center in the summer 2006. PARTICIPANTS: 148 8- to 13-year-old children (132 English speaking, 16 primarily Spanish speaking). MAIN OUTCOME MEASURES: Sorting of food items into common groupings and their names. ANALYSES: Robinson matrices for identification of clusters of food items. RESULTS: Children created on average 11.1 (+/- 4.4) piles with 5.4 (+/- 4.9) cards per pile. Robinson matrix clusters captured 92.4% of the variance in the sorting of food cards. No substantial differences in Robinson clustering were detected across subcategories for each of the demographic characteristics. The label names provided by the children were most frequently categorized as "Taxonomic-Professional" (42.5%), such as meat, fruit, and drinks; or "Script" (26.4%), such as breakfast food, desserts, and snacks. CONCLUSION AND IMPLICATIONS: Children categorized food items into similar clusters but used diverse names to label them. These categories may be used to facilitate food search for researchers in a computerized 24-hour dietary recall for children in this age group.

Mixed foods are similarly categorized by 8-13 year old children.

Food search in a computerized 24h dietary recall (24hdr) for children should be easiest when the categories reflect children's categorization of foods, in contrast to professional categories. This study assessed how 8-13 year old children categorized and labeled mixed foods (e.g. fried rice, lasagna), and how these were influenced by child characteristics. A set of 48 cards with pictures and names of mixed foods from 14 professionally defined food groups was sorted by each child into piles of similar foods. Participants (n=146), including 8-13 year old 130 English speaking, and 16 Spanish speaking children, attended data collection in the summer, 2006. One way ANOVA, pairwise comparisons and Robinson matrices for identification of clusters were used. Children created an average of 10.5 (+/-5.5) piles with 6.0 (+/-4.1) cards per pile. No substantial differences in Robinson clustering were detected across subcategories for each of the demographic characteristics, body mass index, or 6-n-propylthiouracil sensitivity. For the majority of the piles, children provided "taxonomic-professional" (26.0%) labels, such as vegetables, sandwiches and drinks, or "specific-food item" (23.0%) labels, i.e. the name of the food. These categories may be used to facilitate mixed food search in a computerized 24hdr for children in this age group.

Food category purchases vary by household education and race/ethnicity: results from grocery receipts.

OBJECTIVE: To characterize food group purchases from grocery receipts. METHODS: Food shoppers (aged>or=19 years with at least one child aged

Squire's Quest! Dietary outcome evaluation of a multimedia game.

BACKGROUND: Fruit, juice, and vegetable (FJV) consumption among children is low. Innovative programs are needed to enable children to increase FJV intake. Psychoeducational multimedia permits the delivery of interventions as designed and capitalizes on known behavior change principles. DESIGN: Elementary school was the unit of recruitment, assignment, and analysis. Twenty-six elementary schools were pair matched on size and percentage of free or reduced-price lunch, and randomly assigned to treatment or control groups. Data were collected just before and just after the program. SETTING/PARTICIPANTS: All fourth-grade students in participating elementary schools were invited to participate. Data were collected on 1578 students. MAIN OUTCOME Servings of fruit, 100% juice, and vegetables consumed. INTERVENTION: Squire's Quest! is a ten-session, psychoeducational, multimedia game delivered over 5 weeks, with each session lasting about 25 minutes. Based on social cognitive theory, educational activities attempted to increase preferences for FJV through multiple exposures and associating fun with their consumption, increase asking behaviors for FJV at home and while eating out, and increase skills in FJV preparation through making virtual recipes. MEASURES: Four days of dietary intake were assessed before and after the intervention. Assessment was made by the Food Intake Recording Software System (FIRSSt), which conducts a multiple pass, 24-hour dietary intake interview directly with the children. RESULTS: Children participating in Squire's Quest! increased their FJV consumption by 1.0 servings more than the children not receiving the program. CONCLUSIONS: Psychoeducational multimedia games have the potential to substantially change dietary behavior. More research is warranted.

The food intake recording software system is valid among fourth-grade children.

OBJECTIVES: To assess the validity of the Food Intake Recording Software System (FIRSSt) against observation of school lunch and a 24-hour dietary recall (24hDR); and to test the effects of sequencing, observation and a hair sample as a bogus pipeline on accuracy of dietary report. DESIGN: Six-group design systematically varying sequence of self-report (FIRSSt vs 24hDR), observation of school lunch and hair sample as a bogus pipeline manipulation, with random assignment of participants. SUBJECTS/SETTING: 138 fourth-grade students in 2 elementary schools. MAIN OUTCOME MEASURES: Accuracy of reported food consumption was measured in terms of matches, intrusions, and omissions among the FIRSSt, 24hDR, and as observed at school lunch. Students also completed self-report of performance with FIRSSt. STATISTICAL ANALYSIS PERFORMED: t tests, Pearson correlations, analysis of variance, factor analysis. RESULTS: When compared with school lunch observation for one meal, FIRSSt attained 46% match, 24% intrusion and 30% omission rates, while a dietitian-conducted 24hDR obtained 59% match, 17% intrusion, and 24% omission rates. FIRSSt attained 60% match, 15% intrusion, and 24% omission rates against 24hDR for all meals in the previous day. There was no evidence of sequence of assessment affecting accuracy indicators, but there was a weak effect of school lunch observation on percent intrusions. Obtaining a hair sample reduced the omission rate for FIRSSt vs 24hDR and increased the match rate for 24hDR vs observation, thereby enhancing this as a bogus pipeline procedure. Children generally enjoyed completing FIRSSt. Hispanic children were more likely to report problems using FIRSSt. APPLICATIONS/CONCLUSIONS: FIRSSt is somewhat less accurate than a dietitian-conducted 24hDR. However, this lower-cost procedure provides a promising method for assessing diet among children. Observation of consumption at school lunch may be reactive and artificially increase agreement. Obtaining a hair sample as a bogus pipeline may be a valuable technique for enhancing the accuracy of dietary assessment among children.