EAL

GDM: Carbohydrate (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To clarify the effect of dietary fibre naturally present in food included in realistic meals on

gastric emptying
glycemic response
feelings of hunger, satiety, and epigastric fullness

Inclusion Criteria:

taking no drugs

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment: not specified

Study Design: Randomized Controlled Trial. All subjects consumed two test meals on different days and in random order

Intervention:

Subjects were asked to follow a low-fiber, low-glycemic-index diet the evening before each experiment.

High fiber diet (20g/1000 kcal) : whole meal pasta and ground beef, whole meal bread crumbs, tomato puree, minced carrots and homogenized oranges. 717 ml in volume

Low fiber diet (4 g/1000 kcal): white pasta and ground beef, white bread crumbs, tomato juice, orange juice and carrot juice. 672 ml in volume

The meals provided 47% of kcal as carbohydrates, 36% fat, and 17% protein; 870 kcal for men and 700 kcal for women.

Blinding: not specified

Statistical Analysis: the statistical significance of differences between paired results, using Student's t test or the Wilcoxon signed ranks test, as appropriate.

Data Collection Summary:

Timing of Measurements

Subjects consumed test meals and then had measurements completed afterwards.

Dependent Variables

Response to test meals:

gastric emptying time, by ultrasonography at baseline, 30, 60, 120, 180, 240 and 300 minutes after test meal.
blood glucose, by enzymatic glucosidase at 0, 30, 60, 90, and 120 minutes after finishing the meal.
feelings of hunger, satiety and epigastric fullness. Subjects completed a questionnaire before meals, and at 0, 30, 60, 120, 180, 240, and 300 minutes after the meal.

Independent Variables

fiber content: high fiber (20g/1000 kcal) or low fiber (4 g/1000 kcal)

Control Variables

Description of Actual Data Sample:

Initial N: 8 healthy subjects, 5 male, 3 female

Final N: 8

Age: age range 28 - 41 yr

Ethnicity: not specified

Other Relevant Demographics: none specified

Anthropometrics: mean BMI 21.5±1.0

Location: Italy

Summary of Results:

Other Findings

Basal and maximal postprandial antral sections were similar for the two meals:Basal: 283.9±29.5 vs. 340.9±44.7 mm²for the low and the high fiber meal (not significant)
Maximal postprandial section: 1726±101.9 vs. 1593±120.4 mm² (not significant).
Total gastric emptying time was significantly reduced by fiber removal: 186.0±15.6 vs. 231.7±17.3 minutes after the low and high fiber meal, P<0.05.
Blood glucose was higher after the low fiber meal, and the area under the glycemic curve significantly greater 226±23.1 vs. 160±20 mmol/min/dl, P<0.05.
No difference was found in satiety or fullness feelings, but hunger returned more rapidly after the low fiber meal.

Author Conclusion:

Fiber naturally present in food delays gastric emptying of a solid meal, reduces the glycemic response, and delays the return of hunger.

Funding Source:

University/Hospital:

University of Verona (Italy)

Reviewer Comments:

The sample size was quite small. The differences in gastric size seemed large enough to be significant. A larger sample size may have shown a statistical significance.

The take home message here is that foods high in fiber take longer to eat, take up more space in the stomach and take longer to leave the stomach. All of these factors can contribute to modifiying calorie intake for individuals who need to manage their weight.

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?	???
	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?	No
3.	Were study groups comparable?		N/A
	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?		N/A
	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?	???
	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?	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?	Yes
	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?		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)?	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes