EAL

Saturated Fat

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Examine the effects of psyllium and B-glucan intake, in the amounts approved by the FDA for a fiber health claim, on serum lipid risk factors for cardiovascular disease.

Inclusion Criteria:

Inclusion Criteria:

•Ninety-one hyperlipidemic subjects

•Serum LDL-Cholesterol concentrations (>4.1 mmol/L)

•Not taking hypolipidemic agents.

Exclusion Criteria:

Exclusion Criteria:

•Availability for random assignment.

•No clinical or biochemical evidence of diabetes, liver disease, or renal disease.

•Completion of the study (Two 1-month dietary phases, separated by 2-weeks wash-out).

Description of Study Protocol:

1-month before starting the study, subjects followed the National Cholesterol Education Program Step II diet (total fat <30% of energy, saturated fat <7% of energy, and dietary cholesterol <200 mg/d). These guidelines were followed throughout the course study.

Subjects were randomly assigned to either a control diet group or the high-fiber diet group. Each diet group lasted for one month followed by a two -week washout period, after-which the subject where assigned to the other group.

High-fiber and control foods were provided to both groups that provided on average of 36.2% of total daily energy intake. The high-fiber foods contained 1.8-2.5g psyllium or 0.75 g B-glucan/serving.

Data Collection Summary:

Blood samples and blood pressure was measured after fasting 12-14 hours before the start and at the end of weeks 2 and 4 of each phase.

1) Total Cholesterol (Chol) mmol/L

2) LDL Chol mmol/L

3) HDL Chol mmol/L

4) Triacylglycerols (TAG)

5) Apo A-I gm/L

6) Apo B gm/L

7) Total Chol:HDL

8) LDL:HDL

9) Apo B:Apo A-I

10) Blood pressure mmHg

11) CAD risk %

Weight was measured at the start and during biweekly clinic visits in both phases and self-monitored on home scales.

The last 7-days of each phase, subjects recorded their diet after weight food items on electronic scales.

During week four of each phase subjects noted number of bowel movements and flatulence, bloating, and abdominal pain.

Description of Actual Data Sample:

68 (83% of original 91 subjects)

37 men and 31 postmenopausal women

Mean age: 60 + 1 year (33-82 years)

Mean BMI: 25.6 kg/m² + 0.3 (20.0-33.8 kg/m²)

Summary of Results:

With both the control and high-fiber diet, subjects consumed 96 + 1% of the supplements provided.

7.2g psyllium and 0.75g B-glucan average intake for high fiber diet.

No significant body weight change with either the high-fiber diet (-0.1 +0.1kg) or the control diet (-0.1+0.1kg).

There were no significant differences in pretreatment values between the high-fiber (HFD) and control diets (CD) (Table 1).

Significant reductions from pretreatment values were seen in blood lipids after both diets (Table 1).

Mean values were significantly lower after the high-fiber diet than after the control diet for:

1) Total chol (percentage difference between treatments: 2.1+0.7%; p=0.003).

2) TAG (5.2+2.4%; p=0.037).

3) Apo B (2.9+0.8%; p<0.001).

4) Total:HDL (2.4+1.0%; p=0.001).

5) LDL:HDL (2.4+1.0%; p=0.015).

Outcome measures showed no significant difference between men & women, age, and body mass index.

Controlling for weight change or differences in dietary carbohydrate, saturated or polyunsaturated fat, the ratio of polyunsaturated to saturated fatty acids, or dietary chol did not alter the pattern of significance in treatment differences of blood lipids.

Compared to the control diet, high fiber diet reduced cardiovascular disease risk (4.2+1.4%; p=0.003).

Blood pressure was not significantly between the two study diets.

No significant differences were seen in bloating, flatulence, or abdominal pain. Bowel movements were more frequent during the high-fiber than during the control diet (9.6+0.5 compared with 8.6+0.5 movements/wk; p=0.005).

Author Conclusion:

The palpability of and lack of side effects from these foods suggest that consumption of more serving of fiber-supplemented foods will prove acceptable in clinical situations where larger reductions in lipid risk factors for cardiovascular disease are required.

The present level of supplementation is likely to be of benefit of a population basis as one of several dietary strategies to reduce lipid risk factors for cardiovascular disease.

Funding Source:

Government:

Natural Science and Engineering Council of Canada

Reviewer Comments:

I felt this was an excellent, well-designed study.

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)	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?	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?	Yes
	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?	???
	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.)	???
	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?	N/A
	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)?	Yes
	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