Asemi Z, Samimi M, Tabassi Z, Sabihi SS, Esmaillzadeh A. A randomized controlled clinical trial investigating the effect of DASH diet n insulin resistance, inflammation, and oxidative stress in gestational diabetes. 2013, Nutrition, 29: 619-624.PubMed ID: 23466048
- Pregnant women aged 18 to 40 years, diagnosed with GDM at 24 to 28 weeks' gestation
- Pregnant women without a previous diagnosis of glucose intolerance, no previous history of GDM, non-smokers, having GDM based on previously mentioned criteria.
- Premature pre-term rupture of membrane
- Placenta abruption
- Those who needed to commence insulin therapy or were on insulin therapy
- Recommendation of complete bed rest
- Hypothyroidism, kidney or liver disease
- Women taking estrogen therapy.
- Recruitment: The women were recruited in the clinics affiliated with Kashan University of Medical Sciences (Iran) from April to December 2011
- Design: Randomized, two-arm, parallel clinical trial
- Blinding used: All the study personnel and participants were blinded to dietary assignment, but the dietitian who provided dietary education. Randomization was done using a computer-generated random numbers.
- DASH diet
- ?Rich in fruits, vegetables, whole grains, low-fat dairy products, low in saturated fats, cholesterol, refined grains and sweets
- Composition: CHO, 40% to 55%; PRO, 10% to 20%; fat, 25% to 30%
- Sodium intake was less than 2,000mg per day.
- Control diet: Same macronutrient composition.
- Participants were choosing the foods from a prescribed list. The compliance of diet monitored weekly through phone interviews and double-checked by the use of three-day dietary records completed throughout the study.
Non-normality distributed variables used log transformation
Student's T-test and paired-samples T-test were used to analyze the data
P<0.05 was considered statistically significant.
Timing of Measurements
All anthropometric and biochemical assessments were measured at baseline and after four weeks of intervention.
- Fasting plasma glucose (FPG)
- Serum insulin
- Serum high-sensitivity C-reactive protein (HS-CRP)
- Homeostasis of assessment-insulin resistance (HOMA-IR)
- Plasma antioxidant capacity (TAC)
- Total glutathione levels (GSH).
- DASH diet
- Control diet.
Attrition (Final N)
- 32 (16 in DASH; 16 in control)
- Lost to follow-up
- Pre-eclampsia: Four
- Bed rest: One
- Insulin therapy: One.
- Control: Mean, 29.7±5.6 years
- DASH: Mean, 27.7±5.4 years.
Other Relevant Demographics
GTT at baseline was the same between groups except the first hour, when the DASH Group had a higher GTT than Control (203.87mg vs. 190.73mg per dL; P<0.05), respectively.
Pre-pregnant weight, baseline and final weight, pre-pregnancy, baseline and final BMI were not different between the two groups.
|Variables||DASH Diet Group||Control Group||Statistical Significance of Group Difference|
|Mean changes from Weeks 0 to 4||Mean Changes from Weeks 0 to 4|
FPG, fasting plasma glucose
GSH, total glutathione
HOMA-IR, Homeostasis model of assessment - insulin resistance
TAC, total antioxidant capacity.
- DASH Diet Group showed a significant increase in the TAC and GSH levels after four weeks, but the Control Group had a significant decrease (P=0.001)
- Dietary diet results showed an increase in total carbohydrate and fructose intake, but a decrease in simple sucrose consumption with the DASH diet, compared to the control diet; 392±7g vs. 318±42g per day (P<0.0001); 13.4±1.2g vs. 9±1.8g per day (P=0.001); 9.1±0.9g vs. 19.8±1.2g per day (P<0.0001).
- Consumption of the DASH diet in pregnant women with GDM had beneficial effects on FPG, serum insulin levels, HOMA-IR score, plasma TAC and total GSH levels
- The effects of this dietary pattern on pregnancy outcomes need to be investigated in future studies.
- Interpretation of the results may be jeopardized due to the limitations of the statistical analysis as well as the lack of diet adherence
- Small sample size increases risk for type 2 error
- The study also was limited by its short duration
- Limited generalizability due to population studied.
Quality Criteria Checklist: Primary Research
|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|
|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?||No|
|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.)||No|
|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?||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?||No|
|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?||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?||No|
|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?||No|
|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?||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?||No|
|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?||No|
|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?||No|
|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)?||No|
|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?||No|
|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?||Yes|