PWM: Foods and Nutrients (2006)
Mrdjenovic G, Levitsky DA. Nutritional and energetic consequences of sweetened drink consumption in 6- to 13-year-old children. J Pediatr 2003;142:604-10.
PubMed ID: 12838186
Not specified but stated that all were ‘healthy’
- 4-8 week Cornell Summer Day Camp in 1997
- After 1st week of camp, all food and beverages consumed during the week were provided (dinners sent home) and amount eaten weighed; Parents were responsible for returning uneaten dinner + recording additional foods eaten during week as well as food provided by parents on weekends (using standard home measures)
- Note: not clear if same foods were provided every day or varied menus or how often sweetened beverages were ‘served’ vs ‘offered’
- Unlimited access to water, 2% milk, fruit-flavored sweetened beverages at camp; no vending machines with soft drinks
- 100% fruit juice provided at breakfast and some lunches, skim milk (or 2% if not like skim) at breakfast, morning snack, lunch & upon request
- Height and weight taken in am before breakfast during 1st and last week of camp
(not blinded)
Dependent
Daily intake of:
- Solid food (g)
- Energy
- Protein
- Minerals – Ca, Mg, P, Zn
- Vitamins – A, C, folate, riboflavin
Anthropometry:
- Body weight
- BMI
Independent
Daily beverage intake as categorical variable: 0 (none); 1 (<6 oz); 2 (6-12 oz); 3(12-16 oz), 4 (>16 oz) (Note: gram/serving size description not clear):
- Sweetened beverage intake (soda, <100% fruit juice, Kool-Aid, fruit punch, Snapple, etc.)
- Milk (fluid milk, milk shakes)
- 100% fruit juice
Control variables
- age, gender, energy intake, amount served (amount put on serving tray by investigators) [Note: say these used to determine whether sweetened beverage consumption displaced milk; does not say if used for body wt analyses]
Statistics
- Randomized block design for repeated measures (each child = a ‘block’)
- ANOVA
- Multiple linear regression
- To control for both between- & within-subject error & multi-colinearity of data, PROC MIXED used in SAS (?)
Initial N: 30 (selected from a group of 42)
Final N: 21 (70% f/u)
Age: 6-13 y
Ethnicity: most white; 5 minorities
SES: most upper-middle class
Note: no explanation of why 9 children lost to follow-up
Milk intake
- Drank significantly less milk (247 ± 17 g/d) on days consumed >16 oz sweetened drinks than when did not have any (368 ± 14 g/d milk) (P <.0001) (trend observed for every child) – even after adjusting for being served less milk when sweetened drinks were available in excessive amounts
- Drank significantly less milk when large amount of 100% fruit juice consumed – even after adjusting for amount milk served
Solid food
- No effect (p = .03) of sweetened beverages – even after adjusted for amount solid food served
- No effect (p=.37) of fruit juice
Energy intake
- Higher (244 kcal/d more) when sweetened drinks consumed than when they were not (P=.0001). After adjusting for total amt of food and drinks served, total daily energy intake remained relatively constant across all levels of sweetened drink consumption (P=.22) indicating that any observed increase in daily energy intake was result of higher amt of sweetened drinks consumed.
- "Children at highest (sweetened) beverage category had highest daily energy intake, 91% ± 5% RDA. Children at lowest sweetened beverage category achieved 82% ± 5% RDA for energy" (no p value given)
- No discussion of effect of fruit juice
Anthropometry
- Initial body wt negatively associated with sweetened drink (-.43 kg/glass, p<.0001) [no mention of relation with BMI]
- Initial body weight negatively associated with fruit juice (p = .003); no significant relation with BMI (P=.08)
- ‘Children at highest level of sweetened drink intake (>16 oz/d) gained more weight during study (1.12 ± 0.7 kg) than those who consumed 6-16 oz/d (0.32-0.48 ± 0.4 kg); but not statistically significant (P=.4) given small sample size’
- ‘Similar trends in weight gain, just stronger, with excess fruit juice. Children consuming >12 oz/day gained 3.3 kg ± 1.95 kg, whereas those with <6 oz/d gained 0.5 kg ± 0.4 kg (p = .2)’
Nutrient Intake
- Excess sweetened drink consumption (>12 oz/d) vs minimal (<6 oz/d) associated with adjusted (not sure what adjusted for) lower mean daily intakes of protein, Ca, Mg, P, Zn, and vitamin A intakes (P <.0001) and higher vitamin C intake (P <.0001)
- No effect on folate or riboflavin
Results presented in Table III
Government: | USDA |
University/Hospital: | Cornell University |
Weaknesses:
- Not clear how long camp was on average; short time period
- Not clear why final sample size less than initial or if those that were not included in analyses were different than others
- Not clear about control variables in wt/BMI analysis
- Referred to things being different when not significantly so
- No discussion of relation of fruit juice & BMI
- Conclusions not justified from results
Strengths:
- Weighed food intake for weekdays
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? | No | |
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? | No | |
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? | ??? | |
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.) | 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.) | N/A | |
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? | 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.) | N/A | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | Yes | |
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? | No | |
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? | No | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | ??? | |
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? | No | |
6.6. | Were extra or unplanned treatments described? | No | |
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? | 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? | ??? | |
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? | No | |
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)? | No | |
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? | No | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? | No | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | No | |
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? | ??? | |