EAL

PDM: Metabolic Syndrome (2013)

Citation:

Pouteau E, Ferchaud-Roucher V, Zair Y, Paintin M, Enslen M, Auriou N, Mace K, Godin JP, Ballevre O, Krempf M. Acetogenic fibers reduce fasting glucose turnover but not peripheral insulin resistance in metabolic syndrome patients. Clin Nutr. 2010; 29(6): 801-807.

PubMed ID: 20584565

Study Design:

Randomized Crossover Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To investigate whether chronic acetogenic fiber ingestion is associated with an improvement of peripheral insulin sensitivity, endogenous glucose turnover and plasma biomarkers in patients with metabolic syndrome.

Inclusion Criteria:

Male
Aged 18 to 75 years
Body mass index (BMI) 25 to 40kg/m²
Metabolic syndrome as defined by ATP III guidelines
Glycated hemoglobin less than 7% with normal liver enzyme, urea and creatinine concentrations.

Exclusion Criteria:

Presence of diabetes
Taking medication likely to influence lipid metabolism.

Description of Study Protocol:

Design

The study was a double-blind, single center, crossover, randomized controlled trial. The dietary treatments were five weeks long with inclusion of a six-week washout period between treatments.

Blinding Used

Both participants and researchers were blinded.

Intervention

For five weeks, participants ingested daily standardized drinks, with or without 28g of acetogenic fibers, which consisted of 80% acacia gum (more than 80% dietary fiber) and 20% apple pectin (90%±5% soluble fiber).

Statistical Analysis

The required sample size was 19 patients. Taking into account for a dropout rate of 5%, the required number of patients was 20. According to normality distribution, the paired T-test, one sample T-test or non-parametric Wilcoxon signed-rank test was used for comparison of the primary and secondary outcomes between both treatments. All statistical analyses were done with SAS software (version 8/2). The rejection level in statistical tests was equal to 5% (P<0.05). The results are presented as the mean ±SD.

Data Collection Summary:

Timing of Measurements

Anthropometric data and fasting blood samples were collected during all visits. The dietary treatments were five weeks long with inclusion of a six-week washout period between treatments.

Dependent Variables

Blood glucose: Measured using an electrochemical glucose analyzer (Accu-Chek, Roche Diagnostics)
Glycated hemoglobin: Measured using a conventional immunological method
Acetate concentration in plasma: assessed using mass spectrometry
Plasma concentrations of free fatty acids and triglycerides: measured with commercially available kits
Total, high density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels: Measured with enzymatic kits
Plasma concentration of insulin: Measured by immunoassay with commercially available kits.

Independent Variables

For five weeks, participants ingested daily standardized drinks, with or without 28g of acetogenic fibers (acacia gum and pectin). Two drink supplements with 28g of acetogenic fiber per day during the five-week treatment period; one drink was consumed three to four hours before lunch and the other one three to four hours before dinner.

Control Variables

The placebo drink was of identical composition with no fiber.

Description of Actual Data Sample:

Initial N: N=25 men
Attrition (final N): N=21 men
Age: 18 to 75 years old
Anthropometrics: Groups were not significantly different at baseline
Location: France.

Summary of Results:

Key Findings

	Fiber	Control	P-value
Insulin (μUI per ml)	14.4±5.4	14.6±7.7	0.88
Glucose (mmol per L)	5.86±0.71	5.87±1.08	0.56
Free fatty acid (μUI per ml)	664±253	662±222	0.64
Triglycerides (g per L)	2.10±1.91	1.65±1.07	0.25
Total cholesterol (g per L)	1.93±0.34	2.13±0.93	0.25
HDL-C (g per L)	0.40±0.14	0.42±0.10	0.22
LDL-C (g per L)	1.15±0.20	1.23±0.24	0.46
Resting energy expenditure (kcal per day)	1,907±194	1,908±206	0.98

Other Findings

Body weight and body mass index (BMI) were not significantly different at the end of the study
There were no significant differences between fiber and control treatments in terms of insulin, glucose, triglycerides or HDL cholesterol
At the end of the fiber treatment, the fasting endogenous glucose turnover (7.9±1.3μumol per kg) was significantly decreased compared with the control treatment (8.6±1.6 μumol per kg, P=0.03).

Author Conclusion:

The authors concluded chronic acetogenic soluble and readily fermentable fiber intake is associated with a reduction in the fasting endogenous glucose turnover.

Funding Source:

Industry:

Nestle Research Centre

Food Company:

Reviewer Comments:

Relatively small sample size and only men were studied
Dietary interventions were only five weeks long.

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?		???
	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?	No
	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?		No
	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%.)	No
	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?		???
	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?	???
	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?	Yes
	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)?	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?	Yes
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