PDM: Metabolic Syndrome (2013)


Gulseth HL, Gjelstad IM, Tierney AC, Shaw DI, Helal O, Hees AM, Delgado-Lista J, Leszczynska-Golabek I, Karlstrom B, Lovegrove J, Defoort C, Blaak EE, Lopez-Miranda J, Dembinska-Kiec A, Riserus U, Roche HM, Birkeland KI, Drevon CA. Dietary fat modifications and blood pressure in subjects with the metabolic syndrome in the LIPGENE dietary intervention study. Br J Nutr. 2010; 104(2): 160-163.

PubMed ID: 20202290
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To investigate the effect of an isoenergetic change in dietary fat quality and quantity on blood pressure (BP) in subjects with metabolic syndrome (MS). 

Inclusion Criteria:
  • Caucasian, age 35 to 70 years, BMI 20 to 40kg/m2
  • Metabolic syndrome as defined by three or more of the following: 
    • Fasting plasma glucose more than 5.5mmol per L
    • TAG 1.5mmol per L or more
    • HDL-C less than 1.0mmol per L (males) or less than 1.3 (females)
    • Systolic BP (SBP) 130mm Hg or more or diastolic BP (DBP) 85mm Hg or more or on BP-lowering medication
    • Waist circumference (WC) more than 102cm (males) or more than 88cm (females)
  • Anti-hypertensive medication, hormone replacement therapy, multivitamin supplements and non-fatty acid-based nutritional supplements were allowed if the subjects adhered to the same diet regimen throughout the study. 
Exclusion Criteria:
  • Pre-diagnosed diabetes
  • Inflammatory disease
  • Use of statins and anti-inflammatory drugs
  • Fatty acid supplements
  • Alcohol abuse
  • Recent weight change of 3kg or more.
Description of Study Protocol:


Parallel RCT.

Blinding Used

Implied with measurements


One of four isoenergetic diets differing in fat quantity and quality:

  • Two diets provided 38% energy from fat, one with high content (16% of energy) of SFA (HSFA diet) and the other with high content (20% energy) of MUFA (HMUFA diet)
  • The other two diets were low-fat, high-complex carbohydrate (LFHCC) diets that contained 28% energy from fat, with diet LFHCC n-3 including 1 to 2g per day supplement of very-long-chain marine n-3 PUFA and diet LFHCC and diet LFHCCC control including a control high-oleic acid sunflower-seed oil capsule. 

Statistical Analysis

Baseline data are presented as group means and standard deviations, and BP changes are given as mean per group and 95% CI. General linear models (two-way analysis of covariance were used to assess differences in BP between groups, adjusted for baseline BP, center, age and body weight. 

Data Collection Summary:

Timing of Measurements

Screening, baseline and at 12 weeks following start of diet.

Dependent Variables

BP: Automatic BP measuring device according to European Society of Hypertension Guidelines, appropriately sized cuff positioned at the heart level after a rest of 5 minutes. The same arm was used for each measurement and at least two measurements were performed at each visit with the average used for data processing. Pulse pressure (PP) was calculated as the difference between SBP and DBP.

Independent Variables

One of four isoenergetic diets differing in fat quantity and quality:

  • Two diets provided 38% energy from fat, one with high content (16% of energy) of SFA (HSFA diet) and the other with high content (20% energy) of MUFA (HMUFA diet)
  • The other two diets were low-fat, high-complex carbohydrate (LFHCC) diets that contained 28% energy from fat, with diet LFHCC n-3 including 1 to 2g per day supplement of very-long-chain marine n-3 PUFA and diet LFHCC, and diet LFHCCC control including a control high-oleic acid sunflower-seed oil capsule
  • A food exchange model was developed and fat-modified products (margarine, cooking and baking fats, oils, dressing and biscuits) were supplied by Unilever
  • All participants completed a three-day weighed food record and a FFQ to estimate dietary intake. Food records were also completed mid- and post-intervention to assess compliance.


Description of Actual Data Sample:
  • Initial N: 428 (196 males, 232 females)
  • Attrition (final N): 391
  • Age: 53.4 (SD 10.1 ) for men and 55.9 (SD 7.9) for women
  • Ethnicity: Caucasian
  • Anthropometrics: No differences between groups at baseline
  • Location: Eight European centers.
Summary of Results:

Key Findings

  • There were no differences in the changes observed in SBP, DBP or PP between the four dietary groups (P=0.52, 0.24 and 0.78, respectively). There were no differences between hypertensive and normotensive in their response to the intervention. 
  • Body weight remained unchanged in the two high-fat dietary groups, but was slightly reduced in the two low-fat groups
  • In a secondary analysis, HSFA and HMUFA diets were compared and a significant diet-times-sex interaction for PP (P=0.01) was seen
  • In a sex-specific sub-analysis, the effect in males differed between the two diets. The PP increased in the HSFA group by 2.8mm Hg (95% CI:  0.0, 5.7), and it did not change in the HMUFA group
  • There was also a significant diet-times-sex interaction for SBP (P=0.03) and PP (P=0.01) between the HSFA diet and the low-fat diets
  • In a sex-specific sub-analysis, SBP and PP differed between these diets only in males
  • The HFSA diet was associated with an increase in PP and no change in SBP while the low-fat diets were followed by a decrease in SBP [-3.7mm Hg (95% CI: -6.0, -1.4)] and NS change in PP (-1.8mm Hg (95% CI -3.9, 0.3)].   
  • Glycemic, lipid and renal outcomes were not studied.
Author Conclusion:

Altered quantity and quality of dietary fat had no major effects on BP in subjects with the metabolic syndrome. The HFSA diet had minor adverse effects on SBP and PP in males. 

Funding Source:
Government: LIPGENE, an European Union Sixth Framework Program Integrated Project, South-Eastern Norway Regional Health Authority
Unilever, The Netherlands
Food Company:
Norwegian Foundation for Health and Rehabilitation, John Throne Holst Foundation for Nutrition Research
Other non-profit:
In-Kind support reported by Industry: Yes
Reviewer Comments:

Sodium intake was not controlled.

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) No
  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? No
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? No
  4.4. Were reasons for withdrawals similar across groups? ???
  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? No
  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? 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? 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? 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? 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