Disorders of Lipid Metabolism and Cholesterol

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

To determine the effect of dietary intake of low-fat foods containing natural nonesterified plant sterols together with recommended doses of Ca, Mg and K on serum TC and LDL-C in persons with mild to moderate hypercholesterolemia

Inclusion Criteria:

Serum cholesterol between 6 – 8 mmol/L (232-310 mg/dl) and TG < 4 mmol/L (356 mg/dl)

Exclusion Criteria:

Familial hypercholesterolemia, no lipid-lowering or antidiabetic drugs, corticosteroids, androgens or immunosuppressants, history of CVD or uncontrolled HTN in past 3 mos, any revascularization procedure in past 6 mos.

Description of Study Protocol:

Screening (-5 weeks): stopped meds, received individual dietary advice

Baseline:  fasting blood sample, 3-day food record

Placebo Run-In Phase (2 weeks):  received same amts of bread, sausage and yogurt, 3-day food record, fasting blood sample

Randomization:  assigned to placebo or treatment group receiving 1.25, 2.5 and 5.0 g/day plant sterols during each 5 week period for 15 weeks, fasting blood sample

5, 10 and 15 weeks: 3 day food records, fasting blood samples

Data Collection Summary:

TC, TG, HDL-C, LDL-C by Friedewald eqn. Double blind

Description of Actual Data Sample:

93 eligible, 78 subjects aged 25 – 75 years were randomized, 71 completed the trial. Clinical characteristics and serum lipid and lipoprotein values were similar between groups. 

Summary of Results:

Overall, daily changes in intake of various minerals in the active group compared with placebo group were 40% increase in Mg, 15% increase in K, 5% increase in Ca, 11% decrease in Na.

Serum TC and LDL-C decreased significantly in the active group compared to the placebo group, whereas there were no changes in HDL-C or TG concentrations.

Reduction in serum TC was 8% in the active treatment group and 3% in the placebo group (p = 0.0071) and that of LDL-C was 13% in the active treatment group and 5% in the placebo group (p = 0.0070).

 

Author Conclusion:

Our results demonstrate that nonesterified natural plant sterols, incorporated in low-fat food items according to the current methods, are similarly effective in lowering of serum cholesterol. In conclusion, natural nonesterified plant sterols contained in low-fat food items and ingested in moderate doses reduced serum TC and LDL-C concentrations to the same extent as reported previously for esterified plant sterol derivatives added to nutritional fats. The presence of mineral nutrients in doses recommended for blood pressure-lowering did not interfere with the cholesterol-lowering efficacy of the sterols, providing a promising approach to dietary prevention of cardiovascular diseases.

Funding Source:
Government: TEKES
University/Hospital: Helsinki University Hospital, Public Health Institute, Oulu Deaconess Institution Hospital
Reviewer Comments:

Well controlled study. Author notes that according to food diaries, actual amount of plant sterols was 0.91, 1.86, and 4.17 g/day.

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) N/A
 
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? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
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? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
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) N/A
  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.) N/A
  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? 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? N/A
  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? N/A
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
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? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  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)? 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? N/A
  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? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A