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NNNS: Polyols (2010)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To investigate health aspects of isomalt intake in normolipidemic and hyperlipidemic volunteers.

Inclusion Criteria:

Subjects were considered hyperlipidemic with baseline cholesterol level higher than 220mg per dL or triacylglycerol level higher than 172mg per dL.

Exclusion Criteria:
  • Intake of antibiotics less than six weeks prior to the start of the study
  • Use of laxatives, motility-affecting or lipid-altering medications were not allowed during the study
  • History of severe chronic medical disease, including gastrointestinal diseases
  • Severe abdominal discomfort
  • Severe constipation
  • Unusual dietary habits
  • Known or suspected lack of compliance with the study protocol
  • Pathologic clinical parameters (apart from increased blood lipids).
Description of Study Protocol:

Design

Randomized, double-blind cross-over.

Blinding Used

Double-blind.

Intervention

  • Sucrose
  • Isomalt.

Sucrose and isomalt were included in sweet foods during the test periods. The dose was increased slowly from 5g per day to 30g per day in the first week of each test phase.

Statistical Analysis

  • Values are given as means with their standard errors
  • The non-parametric Wilcoxon rank-sum test for paired data was used for comparisons
  • For repeated measurements (renal Ca, phosphate excretion), Friedman repeated-measures ANOVA on ranks were first performed to test for any significant differences among groups
  • When significant, the Tukey test was used to determine the specific differences between means
  • Differences were considered to be significant at P<0.05
  • Statistical analyses were carried out using SigmaStat for Windows version 2.03 (SPSS Inc.). 
Data Collection Summary:

Timing of Measurements

  • Two four-week study periods
  • A seven-day rotating menu including ready-to-eat foods was used
  • During daily visits to pick up foods, the study nutritionist asked about possible effects related to the diet or collecting of feces and urine and were asked to return test meals of food not consumed
  • Body weight measured at entry and then weekly
  • 24-hour urine collections were obtained at the start and at weekly intervals in both phases
  • Blood was collected on the morning before and after each test period following a 12-hour fast
  • Mean transit time was measured from day 21 to day 24 of each study period
  • Fecal samples were collected from day 24 to day 28 of each study period for quantitative analyses.

Dependent Variables

  • Mean transit time and stool weight: Single-stool method and radiopaque markers. For quantitative assessment, each stool was frozen separately, then thawed and stool wet weight and fecal pH value were recorded. Five-day stool collections were pooled using a grinder and dry weight determined after lyophilisation.
  • Urine mannitol: Urinary mannitol concentrations were determined using high-performance liquid chromatography
  • Urinary and fecal calcium and phosphate: Ca and phosphate urinary analyses were performed using colorimetric tests. Fecal Ca and phosphate were measured by flame photometry and ion-exchange chromatography. Apparent balances of Ca and phosphate were estimated by calculation (apparent balance = intake - renal excretion - fecal excretion).
  • Blood lipids, apolipoproteins, lipoprotein (a), oxidized LDL and remnant-like particles: Determined using colorimetric enzyme kits. Apoplipoproteins and lipoprotein (a) were measured using immuno-turbidimetrically. RLP-C was determined using the RLP-Cholesterol Immunoseparation assay. Oxidized LDL was analyses using an ELISA kit.
  • NEFA, leptin and fructosamine in serum: NEFA and fructosamine were determined by enzymatic colorimetric assay kit. Leptin was measured with an RIA kit and were expressed as gender- and BMI-adjusted standard deviation scores.

Independent Variables

  • Sucrose: 30g per day
  • Isomalt: 30g per day.
Description of Actual Data Sample:
  • Initial N: 20
  • Attrition (final N): 19 (12 females, seven males). One volunteer dropped out because of febrile tonsillitis that had to be treated with antibiotics (an exclusion criterion)
  • Age: 21 to 53 years; median 30.5 years
  • Location: Community-based; reported daily to the university hospital's dietetic kitchen for food pick-up.
Summary of Results:

 Key Findings

  • Mean BMI and mean body weight did not differ in the two study periods
  • Subjective intestinal parameters were usually mild to moderate and in no case led to discontinuation of the study
  • The average score of distension was 0.7 in the sucrose and 1.8 in the isomalt phase (P=0.002)
  • In each test phase, pain and nausea were rare events
  • Urinary mannitol excretion was used to assess isomalt intake of the volunteers. Mean renal mannitol excretion was significantly higher with isomalt compared with sucrose at each time point of the respective study phase.
  • Routine biochemical and standard clinical parameters for the assessment of renal and liver functions, clotting and complete blood count were not influenced by isomalt consumption and were comparable in both test phases. Significant differences were only noted on platelet counts (isomalt: 250.0 (SE 13.8) x 103/UL vs. sucrose 242.8 (SE 12.8) x 103/ul; P=0.007). Both parameters remained in the normal range in both periods.
  • Consumption of isomalt had no significant effect on total cholesterol, HDL-cholesterol, LDL-cholesterol, triacylglycerols, apo A-2, apo B100, lipoprotein (a), oxidised LDL or RLP-C. Apo A-1 levels were significantly lower after intervention with isomalt [143.6 (SE 5.4)] compared with sucrose [146.7 (SE 4.8)].
  • In the hyperlipidemia subgroup, all parameters of blood lipids including apo A-1 and LDL:HDL ratio were comparable. A slight reduction of cholesterol levels (265.7 7.5 vs. 232.0 20.5mg per dL; P=0.063) and lower levels of apo B100 (132.2 11.3 vs. 115.0 11mg per dL; P=0.063) and LDL cholesterol (177.0 18.2 vs. 150.0 20.9mg per dL; P=0.156) were noted within the isomalt period compared with baseline.
  • Isomalt consumption had no significant effect on NEFA, leptin and fructosamine as compared with sucrose
  • Urinary and fecal Ca and phosphate excretion, and apparent balance and absorption were not affected by isomalt consumption and were very variable on an individual level
  • Stool consistency and mean transit time were similar in both periods. Stool frequency was moderately, but significantly, higher in the isomalt period (1.3  0.1 vs. 1.1  0.1; P<0.006). There were moderate but insignificant increases in wet weight, dry weight and fecal water content. 

 

Author Conclusion:
  • Data suggest that the consumption of isomalt does not impair metabolic function or induce hypercalciuria
  • High-risk parameters of arteriosclerosis like LDL-cholesterol, oxidised LDL and RLP-C in normolipidaemic or hyperlipidaemic volunteers were not affected
  • In addition, results obtained for parameters of bowel function indicate that isomalt could improve bowel function in constipated persons
  • In conclusion, the present study confirmed that isomalt is well tolerated when consumed for a longer period and does not impair physiological and metabolic parameters.
Funding Source:
Other: not listed
Reviewer Comments:
  • The experimental design is only listed in the abstract and not in the methods section of the paper
  • The randomization method was not given
  • No information was given on the cross-over portion of the design, including if there was a washout period
  • No information was given on the number of normo- or hyperlipidemic subjects, thus impacting statistical analysis, along with no sample-size calculation.
  • Questionable, depending on the description, if a true double-blind study
  • Fecal samples were frozen before analyses of wet weight and pH, which could have impacted the results obtained
  • Company providing test products also measured mannitol, Ca and phosphate
  • Do not think the results support the conclusion that isomalt could improve bowel function in constipated persons.
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? ???
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? ???
  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? ???
  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? ???
  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? ???
  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? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? ???
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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)? ???
  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? No
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? No