EAL

DF: Obesity (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the effects of a dietary fiber supplement added to an energy-restricted diet over six months in overweight adults.

Inclusion Criteria:

Age between 16 and 60 years
Uncomplicated overweight
Attending the nutritional department of Hospital Bichat
Body mass index (BMI) above 25
Stable body weight for three months preceding treatment.

Exclusion Criteria:

Gastrointestinal disease and surgery
Thyroid disease
Insulin dependent diabetes melitus
Pregnancy
Use of the following drugs: Diuretics, spasmolytics, H₂-blockers, antibiotics, corticosteroids or bulk laxatives.

Description of Study Protocol:

Recruitment: Patients attending the nutritional department at Hospital Bichat
Design: Randomized double-blind, placebo-controlled, parallel group design
Blinding used: On a random basis, subjects were given dietary fiber tablets or an identical-looking placebo
Intervention: Personalized hypocaloric diet plus a dietary fiber supplement.

Following a two-week run-in period, individual energy intake was calculated to be 25% to 30% below the energy intake, as recorded using a seven-day recall during the two-week run-in period. In addition to food fiber, dietary fiber intake from the supplement was seven grams per day in the fiber group and was one gram per day in the placebo group. Supplements were provided as seven tablets taken three times per day prior to meals. Supplements contained a mixture of beet, barley and citrus fiber, approximately 90% of which was insoluble.

Statistical Analysis

Intent to treat
Wilcoxon rank-sum test or Fisher-Irwin test, according to the distribution of the variables
Wilcoxon signed rank test was used to analyze changes within treatment groups
Analyses were two-sided
P<0.05.

Data Collection Summary:

Timing of Measurements

The following were collected at baseline, then monthly:
- Body weight
- Height
- Blood pressure
- Hunger feelings evaluated immediately before the three meals
  - Using visual analog scales of 10cm with descriptive anchors, "not at all hungry" and "very, very hungry" at either end.
- Adherence to treatment (tablet counts).
Dietary energy intake was calculated by the seven-day recall method during the two-week run-in period and at six months.

Dependent Variables

Body weight
Energy intake
Hunger feelings
Blood pressure.

Independent Variables

Fiber intake.

Control Variables

N/A.

Description of Actual Data Sample:

Initial N: 52 patients (11 males, 41 females)
Attrition (final N): 23
Age: 16 to 60 years
Ethnicity: Not described
Other relevant demographics: Hospital Bichat is in Paris, France.

Anthropometrics

Same initial age, height, body weight, energy intake and BMI
More females than males were in each group.

Location

Hospital Bichat, Paris, France.

Summary of Results:

Body Weight Reduction

Both groups significant (P<0.0001)
Fiber group (5.5±0.7 kg) was significantly higher (P=0.005) than the placebo group (3.0±0.5 kg)
Significant after two months of treatment and persisted during the remaining four months.

Blood Pressure Reduction

No significant change in systolic blood pressure reduction in fiber (4.4mmHg) and placebo (3.1mmHg) groups
Diastolic blood pressure (DBP) reduced in placebo group (P<0.05)
No significant difference in DBP between fiber (74.4±1.4mmHg) and placebo (75.0±1.8mmHg) groups after treatment.

Hunger Feelings

Initially reduced in both groups
After two months of treatment, increased in placebo group with a significant increase at the end of treatment (P<0.02)
Increased in fiber group after initial reduction, but was significantly lower during remainder of the treatment, compared to the initial value (P<0.0008).

Energy Intake

Intial intake: No significant difference
- Fiber Group: 2,525±122kcal
- Placebo Group: 2,552±128kcal
Treatment Period: No significant difference
- Fiber Group: 1,752±55kcal
- Placebo Group: 1,818±74kcal
End of Treatment: No significant difference
- Fiber Group: 1,989±110kcal
- Placebo Group: 2,183±154kcal.

Side effects similar in both groups.

Author Conclusion:

It is concluded that a dietary fiber supplement is of value in the management of overweight, enhancing weight loss and decreasing hunger feelings.

Funding Source:

University/Hospital:

Karolinska Institute, CHU Bichat

Reviewer Comments:

No report of total fiber intake
Energy intake calculated using the seven-day recall method
55% of patients stopped treatment prematurely but were included in the statistical analysis
Sample size was too small.

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?	No
	2.4.	Were the subjects/patients a representative sample of the relevant population?	No
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)	No
	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?	No
	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?		No
	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.)	No
	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?	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?	No
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	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?		No
	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?	No
	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?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	No
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	Yes