Cardiovascular Disease and Micronutrients

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

Investigation of the effect of conjugated linioleic acids (CLAs), vitamin E and CLAs plus vitamin E on blood pressure and lipid profiles in patients with active rheumatoid arthritis (RA).

Inclusion Criteria:
  • Adults with active rheumatoid arthritis (RA)
  • Evaluation of disease activity was by global physician assessment: Medical history, pain in joints, morning stiffness, inflammation and tenderness by acute phase reactants (c-reactive protein, erythrocytes sedimentation rate, platelet, hemoglobin).
Exclusion Criteria:

Abnormal renal or hepatic function, smoking and history of myocardial infarction, pregnancy, taking vitamins or mineral supplements, hyperlipidemia and taking drugs (e.g., thyroid hormones, estrogens, progesterone, diuretics, beta-blockers).

Description of Study Protocol:
  • Recruitment: Not specified
  • Design: Randomized placebo-controlled trial
  • Blinding used: Double-blind.

Intervention

  • Group C took 2.5g of conjugated linoleic acid equivalent to a two-gram mixture of cis-9, trans-11 and trans-10, cis-12 in a 50:50 ratio
  • Group E took 400mg of vitamin E daily
  • Group CE took both the conjugated linoleic acid and vitamin E
  • Group P took a placebo. 

Statistical Analysis

  • Lipid profile values were reported as mean±SEM
  • Differences between groups were compared by one-way ANOVA (continuous data) or X2 (categorical data)
  • Post-hoc comparisons were performed with Tukey's test
  • Adjustment for differences in baseline covariates and changes in variables during study were performed by ANCOVA
  • Significance was set at P<0.05.
Data Collection Summary:

Timing of Measurements

Measured at baseline and after 12 weeks on the supplement.

Dependent Variables

  • Triglycerides (mg per dL)
  • Total cholesterol (mg per dL)
  • LDL cholesterol (mg per dL)
  • HDL cholesterol (mg per dL)
  • LDL-to-HDL ratio
  • Total cholesterol-to-HDL ratio.

Independent Variables

Supplements

  • Group C: 2.5g conjugated linoleic acid, equivalent to two-gram mixture of cis-9, trans-11 and trans-10, cis-12 fatty acid in a 50:50 ratio
  • Group E: 400mg vitamin E
  • Group CD: Both the 2.5-g conjugated linoleic acid equivalent to two-gram mixture of cis-9, trans-11 and trans-10, cis-12 fatty acid in a 50:50 ratio and the 400-mg vitamin E 
  • Group P: Placebo.
Description of Actual Data Sample:
  • Initial N: 87 (80% male)
  • Attrition (final N): Zero (N=87)
  • Age: Mean, 46 years
  • Ethnicity: Not reported
  • Location: Tehran, Iran.

[Note: No significant differences reported between groups on demographic, anthropometric and biological measures at baseline.]

Summary of Results:

Effect of Vitamin E and Conjugated Linoleic Acid on Serum Lipids

 

Placebo (N=22)
Mean±SEM

Vitamin E (N=21)
Mean±SEM

Serum Vitamin E (mcg/mL) Before
4.83±0.81
5.24±0.63
After

5.03±0.79

6.63±0.92

Triglycerides (mg/dL)

Before
120.45±11.5
120.86±9.34
After

124.91±13.03

132.47±15.07

Cholesterol (mg/dL)

Before
191.32±9.04
191.76±10.68
After

198.27±10.56

201.76±8.82

LDL-C (mg/dL)

Before
104.14±5.48
103.43±5.51
After

114.86±7.47

114.85±6.17 (P<0.05)

HDL-C (mg/dL) Before
49.50±1.94
50.38±2.79
After

49.95±2.26

51.57±1.89

LDL/HDL Before
2.14±0.12
2.12±0.12
After

2.37±0.17

2.26±0.12

Cholesterol/HDL Before
3.93±0.19
3.88±0.19
After

4.08±0.23

3.89±0.19

Other Findings

  • Mean blood pressure was reduced in subjects who took the CLA supplement (P<0.05)
  • Vitamin E decreased CRP
  • Erythrocytes sedimentation rate levels decreased significantly in all groups that took the supplements
  • Those subjects taking both the combined CLA and vitamin E had the rates that were lowered the most (P<0.001).

 

Author Conclusion:

Supplementing with CLA decreased blood pressure and vitamin E decreased CRP. Therefore, supplementation with both could be profitable for prevention of heart disease in RA patients. 

Funding Source:
Industry:
Lipid Nutrition Company and Zahravi Company (supplements)
Pharmaceutical/Dietary Supplement Company:
University/Hospital: Tehran University of Medical Sciences
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) ???
  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? N/A
  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? Yes
  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? 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)? 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