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DLM: Elevated Triglycerides, Carbohydrate and Fat (2007)

Zoppo A, Maggi FM, Catapano AL. A successful dietary treatment fails to normalize plasma triglyceride postprandial response in type IV patients, Atherosclerosis, 146:19-23, 1999.
Study Design:
Non-Randomized Controlled Trial
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To address whether in type IV hyperlipidemic patients the normalization of fasting plasma triglyceride (<200 mg/dl) with an hypolipidemic diet results in a concomitant modification of the postprandial triglyceride (TG) profile.
Inclusion Criteria:

Type IV hyperlipidemia as diagnosed on the finding of repeated 12 h fasting hypertriglyceridemias and familial anamnesis 

Control who were healthy and normolipidemic 

Exclusion Criteria:
Fasting plasma glucose >140 mg/dl, severe hepatic or gastrointestinal diseases, renal insufficiency, pregnancy, and concomitant administration of drugs known to interfere with lipiid and lipoprotein metabolism. 
Description of Study Protocol:


 Not described



Blinding used (if applicable)


Intervention (if applicable)

Hypolipidemic diet of 55% carbohydrate, 23% lipids and 22% portein with a saturated/unsaturated fatty acid ratio of 0.8. 

Statistical Analysis

 The data were compared by the Student's t-test for paired data with the Bonferroni correction, and by analysis of variance using the CSS.Statistica Software, p <0.05 was considered statistically significant. 

Data Collection Summary:

Timing of Measurements

Three months following intervention diet. 


Dependent Variables

  • Variable 1: Blood was collected into disodium-EDTA, ph 7.2 and the plasma, obtained by centrifugation at 2-4oC was immediately used for analysis.  All routine laboratory analyses were performed using a Cobas autoanalyser.  Plasma cholesterol and TG were determined by enzymatic procedures.  HDL cholesterol was determined after precipitation of the apo B-containing lipoproteins by MgCl2 and dextrate sulphate, at a final concentration of 0.01 M and 10 mg/ml, respectively. 
  • Variable 2: An oral fat load (OFL) was given to both controls and patients after a 12 h fast.  It provided 600 mg cholesterol/1000 calories with a P/S ratio 0.3 and was given as 50 g fat/m2 body surface and ingested over less than 10 min.   The drink consisted of cream, fat-free milk, chocolate and sugar and was 65% fat, 20% carbohydrate and 15% protein.  Samples of blood were taken at time 0, immediately befoe the meal, and after 3, 6, 8, and 10 h during which time the subjects remainded fasting except for water. 


Independent Variables

The patients were instructed by a dietitian to follow the hypolidemic diet  of 55% carbohydrate, 23% lipids and 22% protein for 3 months with a  P/S ration of 0.8.  Alcohol was forbidden and total daily calories were to reach and maintain a desirable BMI.  Every second week the patients returned to the lipid clinic for body weight control and a dietary control based on a daily food diary.  The food diary indicated compliance to the diet for the 3 months of the study.

Control Variables


Description of Actual Data Sample:


Initial N: 53 hyperlipidemic patients and 20  normolipidemic healthy controls

Attrition (final N): Same

Age: 49.52 ± 12.04 for patients and 41.60 ± 15.80 for controls

Ethnicity: Not described

Other relevant demographics:

Anthropometrics  BMI for patients was 26.60 ± 2.24 and for controls 23.57 ± 6.87.

Location: Milan, Italy


Summary of Results:



Treatment Group Before Diet

Measures and confidence intervals

Treatment  Group After Diet

Measures and confidence intervals

Statistical Significance of Group Difference

Total cholesterol

261 ± 42.40

231.30 ± 40.45


Total TG

516.39 ± 207.60 

229.13 ± 94.44 



33.49 ± 8.71 

37.77 ± 7.82


Cholesterol/HDL 8.43 ± 3.13 5.86 ± 1.21 <0.01
BMI 26.60 ± 2.25 26.47 ± 2.34 NS

Responders (26)*

Before Diet


After Diet 


Total cholesterol

255.50 ± 41.76 200.62 ± 34.63


Total TG

512.80 ± 171.54 159.23 ± 29.69



34.19 ± 9.40 38.08 ± 8.2 <0.01
Cholesterol/HDL 8.14 ± 3.14 5.42 ± 0.97


BMI 26.53 ± 2.02 26.76 ±2.37 NS

Nonresponders (27)*

Before Diet


After Diet 


Total cholesterol

266.56 ± 43.10 225.52 ±42.48


Total TG

519.85 ± 240.00 296.44 ± 86.01



32.81 ± 8.11 37.48 ± 7.25 <0.01
Cholesterol/HDL 8.71 ± 3.16 6.18 ± 1.40


BMI 26.29 ± 2.83 26.18 ± 2.32 NS

*Responders met the target TG level of <200 mg/dl as per the guidelines at the time of publication.

Other Findings

The response to the OFL was significantly different between the controls and patients at 6 h (p<0.001).   The area under the curve was was 1602 ± 449 mg TG/dl/10 h for controls versus 4996 ± 1674 mg TG/dl/10 h for all patients (p<0.01).  The area for responders was 3914 ± 1482 mg TG/dl/10 h versus 6037 ± 1840 mg TG/dl/10 h for nonresponders (p<0.01).

Author Conclusion:
Postprandial response is not affected by a dietary regimen that effectively reduces plasma fasting TG.
Funding Source:
Government: Consiglio Nazionale delle Ricerche Progetto Finalizzato Aging
University/Hospital: University of Milan (Italy)
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? N/A
  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? N/A
  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? 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? No
  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.) N/A
  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? 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