DF: Diabetes (2008)
To compare the effect of guar incorporated into crispbreads, with that of unprocessed high-fiber foods on blood glucose concentrations in diabetic volunteers.
- Diabetic (five insulin-dependent, one controlled by diet alone)
- Previous participants in a study testing the effect of guar and high-fiber foods on diabetic control.
Not described.
Recruitment
Diabetic subjects that had participated in a previous study examining the impact of guar and high-fiber foods on glycemic control were invited to participate.
Design
- Subjects consumed one of seven test breakfasts every two to four weeks over 4.5 months
- Following an overnight fast and administration of normal medication, dosage meals were eaten over 15 to 20 minutes
- Digital blood samples were collected and analyzed for glucose level every 30 minutes, from time zero to 180 minutes after the meal.
Blinding Used
- N/A
- Blood glucose measurements.
Intervention
- Seven breakfasts were tested:
- Whole-meal bread (88g): 9.0±1.2g fiber
- Whole-meal bread (46g) and guar crispbread (7g): 12.4±1.5g fiber
- Whole-meal bread (46g) and soy beans (96g): 16.5±2.0g fiber
- Guar crispbread (7g) and soy beans (96g): 19.8±2.9g fiber
- Soy beans (75g) and lentils (41g): 15.5±1.7g fiber
- Corn flakes (22g) and whole-meal bread (45g): 7.7±1.4g fiber
- Porridge oats (26g) and whole-meal spaghetti (27g): 4.8±0.8g fiber.
- Edam, cheddar and cottage cheese were used to balance the fat and protein of the guar and leguminous-seed meals, which also included 120g tomato and 500±50ml tea, made with 50ml milk
- The methods for all studies were as follows:
- Following a fast, the meal was eaten in 15 to 20 minutes
- Blood was collected (via finger-prick) at zero, 30, 60, 90 and 120 minutes and analyzed for glucose levels.
Statistical Analysis
- Mean with standard error
- Student’s paired T-test.
Timing of measurements: Blood was collected at zero, 30, 60, 90 and 120 minutes and analyzed for glucose
Dependent variables: Glucose
Independent Variables
- Quantity of guar gum (crispbread) consumed
- Quantity of unprocessed high-fiber foods consumed.
Control Variables
N/A.
- Initial N: Six (two male, four female)
- Attrition: Not described
- Age: 43±5 years
- Ethnicity: Not described
Other Relevant Demographics
- Five subjects receiving insulin (16u to 60u per day)
- One controlled with diet alone..
Anthropometrics
99±3% IBW.
Location
Central Middlesex Hospital, London, England.
Variables |
Fasting Blood Glucose (mmol/L) |
Three-Hour Glucose AUC (mmol/min/L) |
Percentage of Bread Meal |
P-Value |
Bread and Cheese |
11.4±1.7 |
557±156 |
100% |
|
Bread and Guar Crispbread |
11.8±1.6 |
333±138 |
51±16% |
P<0.05 |
Bread and soy beans |
11.4±2.1 |
365±158 |
65±13% |
P<0.05 |
Guar Crispbread and Soy Beans |
10.3±2.1 |
153±71 |
25±8% |
P<0.001 |
Soy Beans and Lentils |
11.8±1.9 |
209±111 |
29±11% |
P<0.092 |
Porridge and Spaghetti |
12.9±2.7 |
560±263 |
95±49% |
|
Cornflakes and Bread |
12.8±2.9
|
552±207 |
108±30% |
Guar crispbread and soybean meal was the most effective at decreasing glycemic response to a breakfast meal.
Other Findings
All meals were well tolerated and consumed completely.
The addition of a combination of a purified fiber product (guar crispbread), in combination with a leguminous fiber in its whole form (soy beans), led to a significant decrease in post-prandial glucose in diabetic individuals. This combination may decrease the quantity of fiber consumption required to see an effect.
Not-for-profit |
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- Poor description of limited study sample (six people; inclusion and exclusion criteria not explicitly specified)
- Test meals varied in fiber and macronutrient content, so the effect of type of food vs. fiber content cannot be differentiated
- Attrition (N=4) for two of the test meals may be responsible for lack of statistical significance
- No discussion of limitations.
Quality Criteria Checklist: Primary Research
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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? | No | |
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? | No | |
2.2. | Were criteria applied equally to all study groups? | N/A | |
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) | Yes | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | No | |
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%.) | No | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | No | |
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? | Yes | |
5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | No | |
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? | No | |
6.6. | Were extra or unplanned treatments described? | No | |
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? | No | |
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? | No | |
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? | No | |
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)? | 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? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |