To investigate the relationship between ready-to-eat (RTE) cereal consumption and BMI of school-aged children (ages 4 to 12 years) using a 14-day food intake methodology.
- To be included in the study, a minimum of seven days of food collection was required, however no child had less than that number (92% of children had complete diaries with food intake data for all 14 days).
- At risk of being overweight: at or above the 85th percentile but less than the 95th percentile of BMI for age.
- Overweight: at or above the 95th percentile of BMI.
Recruitment
The study utilized food consumption data collected by The NPD Group from February 1998 through January 1999. Reporting is distributed evenly throughout the year to be sensitive to seasonal eating habits.
Design
General Mills Bell Institute of Health and Nutrition developed a 14-day food diary, a methodology which combines 14-day food diary data with portion size data from the USDA’S CSFII and nutrient data from the University of Minnesota’s NDS-R, allowing users to categorize the population based on “usual” consumption of food categories, specific foods, and/or specific brands of foods and determines dietary differences versus their “non-consuming” counterparts.
Each household maintained a daily fating diary for two weeks. Portion size data were estimated from the CSFII (1989-91 and 1994-96). Estimated mean daily intake values for the following nutrients were reported: carbohydrate, sugar, fat, saturated fat, protein, cholesterol, sodium, dietary fiber, vitamin A, vitamin E, vitamin C, thiamin, riboflavin, niacin, vitamin B-6, folate, calcium, magnesium, iron, zinc, and energy (kilocalories).
Self-reported weights and heights were recorded in the diary and used to calculate BMI.
Statistical Analysis
Analysis of variance (determine if BMI differed among cereal consumption tertiles in each of three age groups, 4 to 6, 7 to 9, and 10 to 12 years), t tests (performed where differences were found among the tertiles), logistic regression (analyze the association between cereal consumption pattern and risk for overweight in each of three age groups and for all ages), Wald chi-square test (examine contrasts between possible pairs of cereal tertiles), another analysis of variance (intakes of 21 key nutrients among cereal consumption tertiles with post hoc comparisons).
Timing of Measurements
14-day intake record taken throughout the year for 1 year.
Dependent Variables
Body mass index
Independent Variables
Nutrient intake, ready-to-eat cereal consumption
Control Variables
Age
Initial N: 603 children (from a sample of 2000 households, or approximately 5000 subjects)
Attrition (final N): 603
Age: 4 to 12 years
Ethnicity: White (87%), nonwhite (13%)
SES: Income:
- >$40 000 (53%),
- $30 000-$39 000 (13%),
- $20 000-$29 000 (15%),
- $12 500-$19 000 (9%),
- <$12 500 (10%)
56% employed
Anthropometrics (e.g., were groups same or different on important measures)
Location: 50 U.S. states
Statistically significant inverse relationship between BMI and frequency of RTE cereal consumption (p<0.01) within each age group as well as for the total sample. Children aged 4 to 12 years who consumed eight or more servings of RTE cereal in two weeks had significantly lower BMI compared to the children who consumed two or fewer servings during a two-week period (p<0.0001).
Significant inverse relationship between the population at risk for being overweight and frequency of cereal consumption (p<0.01). The proportion of children aged 4 to 12 years at risk for overweight or overweight (according to CDC standards) is 33.67%. When children aged 4 to 12 ate RTE cereal eight or more times in two weeks that risk lowers to 21.3%. Conversely, when children at RTE cereal zero to three times in two weeks their risk for overweight increases to 47.4%. This inverse trend is consistent across each of the age groups (4 to 6, 7 to 9, and 10 to 12 years).
Energy intake was not statistically significantly different across cereal consumption tertiles, there were differences in intakes of fat, cholesterol, vitamin A, vitamin B-6, thiamin, riboflavin, niacin, folate, calcium, iron, and zinc. Calcium, iron, and zinc intake increased from the low cereal tertile to the upper tertile. As seen with BMI, there was a significant inverse relationship with frequency of RTE cereal consumption and daily fat intake (p<0.01) and daily cholesterol intake (p<0.01).
Fat (g) intake by tertile of cereal consumption: =3 servings (68.7g±20.3g), 4-7 servings (65.9±20.0g), =8 servings (61.7g±17.1g).
Children who consumed RTE cereal most frequently had the most appropriate age-related BMI, were least likely to be at risk for overweight, and had the most positive nutrient intake profiles. Children who ate cereal most frequently were children who most often ate breakfast.
| Government: | NIH, NHLBI |
Strengths:
When applied to the total sample, it can be expected that mean intakes approximate estimates of intake provided by dietary survey data. (average intakes of these children are similar to that reported in other large population-based surveys).
Recording of 14 days of food consumed – makes it possible to determine additional associations between other food patterns and categories with the BMI of children as well as adults.
Limitations:
Energy intake was not correlated with BMI due to small sample size and assumptions required in making estimates of intake.
Nutrient intake data do not describe precisely the actual intakes of the children and therefore the adequacy or inadequacy of their diets.
Food records were self-reported.
Assumption that an average serving size applies to all persons of same age and gender in the sample, which clearly results in errors of the estimates for individual persons.
Other Comments:
Assessed but did not control for energy intake. Relationship is assessed between cereal consumption and overweight, but not necessarily between breakfast eating and overweight.
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Quality Criteria Checklist: Primary Research
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| Relevance Questions | |||
| 1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | N/A | |
| 2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
| 3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
| 4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | N/A | |
| Validity Questions | |||
| 1. | Was the research question clearly stated? | Yes | |
| 1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
| 1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
| 1.3. | Were the target population and setting specified? | Yes | |
| 2. | Was the selection of study subjects/patients free from bias? | Yes | |
| 2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | Yes | |
| 2.2. | Were criteria applied equally to all study groups? | Yes | |
| 2.3. | Were health, demographics, and other characteristics of subjects described? | Yes | |
| 2.4. | Were the subjects/patients a representative sample of the relevant population? | Yes | |
| 3. | Were study groups comparable? | Yes | |
| 3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | N/A | |
| 3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | N/A | |
| 3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
| 3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | Yes | |
| 3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | Yes | |
| 3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
| 4. | Was method of handling withdrawals described? | Yes | |
| 4.1. | Were follow-up methods described and the same for all groups? | Yes | |
| 4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | Yes | |
| 4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
| 4.4. | Were reasons for withdrawals similar across groups? | Yes | |
| 4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
| 5. | Was blinding used to prevent introduction of bias? | ??? | |
| 5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | N/A | |
| 5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | ??? | |
| 5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | ??? | |
| 5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
| 5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
| 6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | Yes | |
| 6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | N/A | |
| 6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
| 6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | N/A | |
| 6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
| 6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | N/A | |
| 6.6. | Were extra or unplanned treatments described? | N/A | |
| 6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | N/A | |
| 6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
| 7. | Were outcomes clearly defined and the measurements valid and reliable? | No | |
| 7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
| 7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
| 7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | N/A | |
| 7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | No | |
| 7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
| 7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
| 7.7. | Were the measurements conducted consistently across groups? | Yes | |
| 8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
| 8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
| 8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
| 8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
| 8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | N/A | |
| 8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | Yes | |
| 8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
| 8.7. | If negative findings, was a power calculation reported to address type 2 error? | N/A | |
| 9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
| 9.1. | Is there a discussion of findings? | Yes | |
| 9.2. | Are biases and study limitations identified and discussed? | Yes | |
| 10. | Is bias due to study's funding or sponsorship unlikely? | ??? | |
| 10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
| 10.2. | Was the study free from apparent conflict of interest? | ??? | |