EAL

DLM: Diet Composition (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate effects of a Mediterranean style diet with isocaloric substitution of CHO and MUFA for SFA fat on in vivo and in vitro glucose metabolism.

Inclusion Criteria:

Healthy
Normolipidemic (total plasma cholesterol less than 5.2mmol per L)
Attending University of Cordoba
Less than 30 years of age
No evidence of chronic disease (hepatic, renal, thyroid or cardiac dysfunction)
No excessive physical activity.

Exclusion Criteria:

Hyperlipidemic (total plasma cholesterol 5.2mmol per L or more)
Not a student at University of Cordoba
More than 30 years of age
Evidence of chronic disease (hepatic, renal, thyroid or cardiac dysfunction)
Excessive physical activity.

Description of Study Protocol:

Recruitment

Students at University of Cordoba, Spain.

Design

RCT cross-over design.

Blinding used:

Objective laboratory tests.

Intervention

All subjects had initial 28-day high SFA diet with energy distribution as 47% carbohydrate, 15% protein, 38% fat (20% as SFA, 12% MUFA, 6% PUFA)
Participants then randomized to crossover trial to start with one of two diets; each diet intervention lasted 28 days.
- High CHO diet (57% CHO, 15% protein, 28% fat (less than 10% SAFA, 12% MUFA, 6% PUFA)
- Mediterranean diet (47% CHO, 15% protein, 38% fat (less than 10% SAFA, 22% MUFA, 6% PUFA).

Statistical Analysis

ANOVA for repeated measures to analyze differences in plasma blood lipids, glucose, basal glucose and insulin-stimulated uptake between dietary phases
Tukey's post-hoc test to identify differences between groups
Correlation analysis with Pearson's correlation coefficient
P<0.05 considered statistically significant
data presented as means±standard deviation.

Data Collection Summary:

Timing of Measurements

Baseline (beginning of SFA diet).

Dependent Variables

Serum lipids (TG, total -, HDL- , LDL-cholesterol)
Fasting glucose
Fasting insulin
Glucose uptake in monocytes.

Independent Variables

High CHO diet (57% CHO, 15% protein, 28% fat (less than 10% SAFA, 12% MUFA, 6% PUFA)
Mediterranean diet (47% CHO, 15% protein, 38% fat (less than 10% SAFA, 22% MUFA, 6% PUFA).

Description of Actual Data Sample:

Initial N: 59 (30 males, 29 females)
Age: 23.1±1.8 years
Anthropometrics: BMI, 22.87±2.45kg/m² (remained constant throughout the study)
Location: Cordoba, Spain.

Summary of Results:

Key Findings

No difference in TG among diets
Total- , HDL- , and LDL-cholesterol higher in high saturated fat diet, but not significantly different in high CHO or Mediterranean diet.

**Mean Plasma Lipids after Diet Interventions**
Variables	High Saturated Fat Diet	High CHO Diet	Mediterranean Diet
Triglycerides (mmol per L)	0.77±0.3	0.78±0.2	0.79±0.3
Total cholesterol (mmol per L)	0.77±0.3^ab	3.67±0.7	3.74±0.7
HDL-cholesterol (mmol per L)	1.12±0.3^ab	0.99±0.2	10.3±0.2
LDL-cholesterol (mmol)	2.80±0.5^ab	2.32±0.5	2.34±0.6

^a Significantly higher compared to CHO diet.

^b Significantly higher compared to Mediterranean diet.

Other Findings

No difference in TG for any treatments
Fasting glucose, fasting insulin, fasting free fatty acids, steady state plasma glucose were higher after SFA diet; however, there was no difference in values between measures post CHO and Mediterranean diets
Correlation between steady state plasma glucose and fasting free fatty acid values R=0.45; P=0.0001.

Author Conclusion:

Funding Source:

Government:

CAICYT; Spanish Ministry of Health; Andaluz Health Service

Reviewer Comments:

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?	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)	Yes
	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.)	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?	N/A
	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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%.)	N/A
	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?	Yes
	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?	N/A
	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?	Yes
	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?	Yes
	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?	Yes
	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?	N/A
	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)?	Yes
	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?		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