EAL

PWM: Foods and Nutrients (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine whether diet composition is related to percentage body fat in children aged 1.5 to 4.5 years.

Inclusion Criteria:

Children age 1.5 to 4.5 years from one of eight geographical areas in Great Britain.

Exclusion Criteria:

None specified.

Description of Study Protocol:

Recruitment

Eight distinct geographical areas were chosen as recruitment sites, with a plan to select 12 children from each area for a predicted total sample size of 96 subjects
Subjects identified by one of three methods
- Approaching randomly selected addresses
- Obtaining referrals from those households contacted
- Locating families via community playgroups
Quota sampling was used to ensure an even distribution by age and sex in three groups(1.50 to 2.49 years, 2.50 to 3.49 years and 3.50 to 4.49 years).

Statistical Analysis

Associations between dietary intake variables and percentage body fat: Pearson's product-moment correlation coefficients
Differences in percentage body fat by tertiles of intake for each macronutrient: One-way analysis of variance
Model of relations between dietary intake variables, habitual physical activity and body composition: Multiple regression analysis.

Data Collection Summary:

Timing of Measurements

Four-day food weighed food record was conducted during the 10-day urine collection period for doubly labeled water

Dependent Variables

Percent body fat: Body composition assessed by measurement of total body water using oxygen-18 dilution method; % body fat was calculated from fat mass and body weight.

Independent Variables

Dietary intake: Total energy and energy from fat, carbohydrate and protein (four-day weighed food record completed by child’s mother or primary caregiver after intensive training); Intake recorded on four consecutive days including both weekend days.
Physical activity level:
- TEE calculated from doubly labeled water technique
- BNR: Predicted using separate equations for boys and girls, and for subjects younger and older than three years
- Physical activity level calculated as TEE/BMR.

Control Variables

Gender.

Description of Actual Data Sample:

Initial sample: N=93 children
Withdrawals/Drop-outs: 16 subjects were excluded from the analyses because they had unacceptable data arising from either poor parental compliance in urine sample collection or analytic problems
Final sample: N=77
Age: Total sample: 3.08±0.81 years; Boys (N=39): 3.09±0.82 years; Girls (N=38): 3.08±0.81 years
Location: Great Britain
Race/Ethnicity: Not specified
SES: Not specified, although care was taken to include a wide range of families with socioeconomic diversity.
Anthropometrics:

**Anthropometrics and Physical Activity Level Variables (Mean±S.D.)**
	Total Sample	Boys	Girls
Height (cm)	95.8±7.6	96.7±7.4	94.9±7.8
Weight (kg)	15.0±2.4	15.0±2.5	14.9±2.3
BMI (kg/m²)	16.3±1.3	16.0±1.4	16.5±1.2
Body fat (%)	24.0±5.9	23.1±6.0	24.9±5.7
TEE (kJ/d)	4,981±963	5,115±1009	4,845±906
BMR (kJ/d)	3,321±355	3,451±337	3,191±328 *
PAL (TEE/BMR)	1.51±0.28	1.49±0.28	1.52±0.27

* Significantly different from boys, P<0.01 (independent T-test)

Summary of Results:

Dietary Intake

Energy intake: 4,759 kJ per day
Carbohydrate: 57.4%
Fat: 30.5%
Protein: 12.1%
No significant difference between boys and girls.

Percentage Body Fat and Dietary Intake Variables

No significant correlations (r=0.11 for total sample; boys: 0.08; girls: 0.10).

Percentage Body Fat By Tertiles of Intake

No significant differences in percentage body fat among the three tertiles for total energy intake or percentage of energy from carbohydrate, fat or protein.

Relationship Between Dietary Intake, Habitual Physical Activity and Body Composition

Physical activity had a significant influence on body composition (P<0.001)
Total energy and macronutrient intakes did not affect body composition.

Author Conclusion:

The authors found no relations between dietary intakes of total energy, fat, carbohydrate or protein and % body fat in children
The relation between fat intake and body fat may develop over time and may not be evident in pre-school children
Habitual physical activity may be more influential than diet composition in determining percentage body fat in young children.

Funding Source:

University/Hospital:

Queensland University of Technology (Australia)

Reviewer Comments:

Strengths: Variables were measured with highly accurate tools.

Limitations:

Cross-sectional design
Fat intake was moderate. At higher levels of fat intake, a relationship may be seen. Levels of intake for each tertile not given, so this can't be evaluated.

Quality Criteria Checklist: Primary Research
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)	Yes
	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)	Yes

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?	???
	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?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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")?	Yes
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?	N/A
	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?		Yes
	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.)	Yes
	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?	???
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?	Yes
	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?	Yes
	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?		Yes
	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?	Yes
	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)?	N/A
	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes