EAL

DLM: Plant Stanols and Sterols (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to examine the effects of plant sterol and stanol consumption on lipid and lipoprotein metabolism, plasma hydrocarbon carotenoid concentrations, enzymatic antioxidant systems, plasma markers of oxidized lipids, DNA damage and markers of endothelial function and low-grade inflammation in subjects on current statin treatment.

Inclusion Criteria:

Current treatment with a 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor (statins) (history of CVD for more than six months)
Age 18 to 65 years
Body mass index (BMI) 32kg/m² or more
No proteinuria or glucosuria
Diastolic blood pressure of 95mm Hg or less
Systolic blood pressure of 200mm Hg or less.

Exclusion Criteria:

Clinical manifestations of liver disorders
Cardiovascular disease (CVD) for less than six months
Type 2 diabetes mellitus.

Description of Study Protocol:

Recruitment

Participants were recruited via posters in the university and hospital buildings and via local newspaper advertisements.

Design

Randomized, placebo-controlled intervention trial
All participants followed a four-week run-in period, during which time they consumed 30g daily of a control margarine without added plant sterols or stanols in place of their own margarine or butter
After the run-in period, participants were randomly allocated to one of three experimental groups, which were stratified for sex and age
For 16 weeks, each group consumed 30g daily of one of the following "light" (40% fat) margarine:
- Control margarine
- Plant sterol-enriched margarine
- Plant stanol-enriched margarine.

Blinding Used

Double-blind.

Intervention

Participants were asked to replace their own margarine or butter with the "light" (40% fat) margarine, of which 30g should be consumed daily, divided over at least two meals
After a four-week run-in period during which time all subjects consumed the control margarine, participants were randomly assigned to one of three experimental groups, stratified for sex and age
For 16 weeks, participants consumed 30g daily of one of the following "light" (40% fat) margarine:
- The first group consumed the control margarine
- The second group consumed the plant sterol-enriched margarine (30g margarine contained 2.5g plant sterols)
- The third group consumed the plant stanol-enriched margarine (30g margarine contained 2.5g plant stanols)
Participants were asked not to change their habitual diet, level of physical exercise, smoking habits, or use of alcohol during the study.

Statistical Analysis

Differences in changes between treatment groups were analyzed by one-way analysis of variance
When a significant diet effect was found, treatments were compared pair-wise and corrected for three group comparisons using the Bonferroni multicomparison test
Contrast analysis was performed to analyze the effects of plant sterol and stanol consumption as a group against the control group.

Data Collection Summary:

Timing of Measurements

Fasting blood samples drawn in weeks zero, three, four, seven, 19 and 20
Food frequency questionnaire completed at the end of the run-in and experimental periods.

Dependent Variables

Dietary intake:
- Energy (MJ)
- Fat (energy percentage)
- Saturated fatty acids (SAFA) (energy percentage)
- Monounsaturated fatty acids (MUFA) (energy percentage)
- Polyunsaturated fatty acids (PUFA) (energy percentage)
- Protein (energy percentage)
- Carbohydrates (energy percentage)
- Cholesterol (mg per MJ)
Serum lipids and apolipoproteins:
- Total cholesterol (TC) (mmol per L)
- High-density lipoprotein (HDL) cholesterol (mmol per L)
- Triacylglycerol (mmol per L)
- Low-density lipoprotein (LDL) cholesterol (mmol per L)
- Apolipoprotein A-1 (ApoA-1) (mg per dL)
- Apolipoprotein B (mg per dL)
- TC/HDL ratio (units)
Lipid-soluble antioxidant concentrations
- Hydrocarbon carotenoids
- Lycopene
- α-Carotene
- β-Carotene
- Oxygenated carotenoids
- Phytofluene
- Lutein
- Crytopxantin
- Total tocopherol
Enzymatic antioxidant concentrations
- Catalase (k per g Hb)
- Glutathione peroxidase (GpX) activity (mmol NADPH per g Hb per minute)
- Super oxide dismutase (SOD) (U per mg Hb)
Serum plant sterols and cholesterol precursors:
- Sitosterol
- Campesterol
- Sitostanol
- Campestanol
- Lathosterol
LDL-receptor messenger ribonucleic acid (mRNA)
Markers of endothelial function and low-grade inflammation
- Oxidized LDL (Ox-LDL) (pg per ml)
- Ox-LDL/apoB
- 15-keto-dihydro-prostaglandin F2 (15-PDGH)
- Thiobarbituric acid reactants (TBARS) (μmol per L)
- intercellular adhesion molecule 1 (ICAM-1) (ng per ml)
- vascular cell adhesion molecule 1 (VCAM-1) (ng per ml)
- E-selectin (ng per ml)
- monocyte chemotactic protein-1 (MCP-1) (pg per ml)
- C-reactive protein (CRP) (mg per L)
- 7-hydro-8-oxo-2-deoxyguanosine (8-oxo-dG) (8-oxo-dG/10⁶dG)

Independent Variables

Type of margarine consumed (control margarine, plant sterol-enriched, or plant stanol-enriched).

Description of Actual Data Sample:

Initial N

45.

Attrition (Final N)

43 (22 males; 21 females) completed study
41 (20 males; 21 females) with statistical analyses
- Control group: Four males, seven female
- Plant sterol group: Eight males, seven females
- Plant stanol group: Eight males, seven females.

Average Age (Years; ± Standard Deviation)

Control group: 57.8±5.8
Plant sterol group: 58.4±9.9
Plant stanol group: 58.7±7.8.

Anthropometrics

BMI (kg/m²):

Control group: 27.3±2.4
Plant sterol group: 26.4±2.8
Plant stanol group: 26.8±2.9.

Location

The Netherlands.

Summary of Results:

Key Findings

Baseline characteristics were not significantly different between groups
Dietary intake did not change significantly during the study
Participants consumed approximately the targeted amount of margarine (30g daily), so that the sterol group would have consumed 2.5g plant sterols daily and the stanol group would have consumed 2.5g plant stanols daily.

Serum Lipids and Apolipoproteins

Total cholesterol levels were reduced by 6.9% (approaching statistical significance), and LDL cholesterol levels were reduced statistically significantly by 10.3% in the sterol and stanol ester groups
No significant change in HDL cholesterol, tricylglycerol, LDL cholesterol, ApoA-1, ApoB, or TC/HDL ratio was found between groups
No significant difference in cholesterol-lowering effect was found between plant sterols and stanols.

Variables	Control Group Mean ± Standard Deviation	Plant Sterol Group Mean ± Standard Deviation	Plant Stanol Group Mean ± Standard Deviation	P-value Control vs Plant Sterol/Stanol	P-value plant sterol vs. stanol
Total Cholesterol (mmol per L)
Run in	5.42±0.67	5.75±1.10	5.59±0.89
Experimental	5.46±0.77	5.45±1.11	5.19±1.05
Change	0.04±0.42	-0.30±0.56	-0.40±0.61	0.052	0.628
LDL cholesterol (mmol per L)
Run in	3.20±0.57	3.57±1.04	3.44±0.80
Experimental	3.22±0.43	3.30±1.01	3.02±0.88
Change	0.01±0.37	-0.27±0.39	-0.42±0.53	0.027	0.339

Plant Sterols and Cholesterol Precursors

Cholesterol-standardized campesterol and sitosterol were increased significantly in the plant sterol group and decreased significantly in the plant stanol group
Cholesterol-standardized campestanol and sitostanol concentrations did not change significantly in any of the groups
Changes in cholesterol-standardized lathosterol concentrations were not significantly different between the three groups.

Variables

Plant Sterol Group

Change

P-value Control vs. Plant Sterol

Plant Stanol Group

Change

P-value Plant Sterol vs. Plant Stanol

Cholesterol-standardized campesterol

+59%

0.004

-84%

<0.001

Cholesterol-standardized sitosterol

+42%

0.022

-64%

<0.001

LDL-receptor mRNA

Expression of LDL-receptor mRNA did not change in the plant sterol and stanol groups as compared with the control group.

Antioxidants and Markers of Endothtelial Function and Low-grade Inflammation

Plant sterol and stanol consumption did not affect:
- LDL-cholesterol-standardized concentrations of α-carotene, β-carotene, or lycopene; the sum of these carotenoids; or other lipid soluble antioxidants
- enzymatic antioxidants (RBC catalase and SOD concentrations or glutathione peroxidase activity)
- markers of oxidative stress (oxLDL, MDA, 15-PGDH, 8-oxo-dG concentrations)
- markers of low-grade inflammation, endothelial function, and oxidative damage (ICAM, VCAM-1, E-selectin, MCP-1, and CRP).

Author Conclusion:

Plant sterol or stanol consumption effectively lowered serum LDL cholesterol concentrations in subjects on statin therapy that have a history of CVD and have increased endothelial dysfunction. No effects on lipid-soluble and enzymatic antioxidants, markers of DNA damage or lipid peroxidation were observed. Despite the reduction in LDL cholesterol, markers of endothelial function and low-grade inflammation did not change. Most likely, the pleiotropic effects of statin treatment may have overruled these effects.

Funding Source:

Government:

Netherlands Organization for Health Research and Development (Program Nutrition: Health, Safety and Sustainability)

Industry:

Raisio Group

Food Company:

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?	???
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.)	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?	No
	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?	???
	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?	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?	???
	6.6.	Were extra or unplanned treatments described?	???
	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)?	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?	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?		???
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	No