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Vegetarian Nutrition

VN: Therapeutic Vegetarian Diets and Attrition (2009)

Citation:

Geppert J, Kraft V, Demmelmair H, Koletzko B. Microalgal docosahexaenoic acid decreases plasma triacylglycerol in normolipidaemic vegetarians: a randomised trial. Br J Nutr. 2006 Apr; 95 (4): 779-786.

PubMed ID: 16571158
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To investigate the effects of a relatively low dose of DHA derived from microalgae on conventional cardiovascular risk factors and on several safety parameters in normolipidemic vegetarians.

Inclusion Criteria:
  • Adherence to a vegetarian diet for at least one year (no meat, less than one fish meal per month)
  • At least 18 years old
  • BMI between 18kg/m2 and 25 kg/m2.
Exclusion Criteria:
  • An intake of medication with known influence on lipid metabolism during the last three months
  • Intake of omega-3 fatty acid supplements
  • Presence of metabolic, cardiovascular, renal, neurological diseases or pregnancy and lactation.

 

Description of Study Protocol:

Recruitment

  • Posters displayed in health food shops and on the university campus and through personal contacts in the Munich area
  • Participants received a financial compensation of 200 Euro each for their participation.

Design

  • A randomized double-blind, placebo-controlled intervention study with two parallel groups
  • Participants were randomly assigned to treatment or placebo with stratification for gender.

Blinding Used

  •  A description was not provided. It was stated in the design that it was double blinded.

Intervention

  • Participants consumed 2.28g daily of either DHA-rich oil from microalgae Ulkenia sp. providing 0.94g DHA or the same amount of olive oil as placebo for eight weeks
  • Prior to visit, participants had to complete a questionnaire on medications, metabolic disorders, CVD, dietary supplements, frequency of fish and egg consumption and a three-day dietary record (two weekdays and one weekend day)
  • During intervention subjects noted side effects, signs of illness, intake of medication and number of capsules not consumed
  • At the end of the intervention the participants recorded their diets again for three days 
  • At baseline and after 50 to 60 days of intervention, fasted blood samples, body weight, height, BP and heart rates were measured
  • Telephone interviews were done every two weeks to monitor compliance, side effects and intercurrent disease
  • Compliance was assessed by counting leftover capsules and calculated as percentage of prescribed capsules taken.

Statistical Analysis

  • Student unpaired T-test (normally distributed), Mann-Whitney U test (not normally distributed)
  • Wilcoxon non parametric tests, and student's T-test for within group changes
  • Correlations, chi-square tests and Fischer's exact tests were applied accordingly
  • Significance level of P<0.05 was used.
Data Collection Summary:

Timing of Measurements

 Measurements were taken at baseline and after 50 to 60 days of intervention.

Dependent Variables

  • Fasted blood samples: Plasma lipids, erythrocyte phosphatidylcholine, phosphatidylethanolamine and total lipids (measured and analyzed by capillary GLC)
  • TG, total and HDL cholesterol concentrations (determined in heparin plasma by standard enzymatic methods on a Cobas Integra 800 automated sample processor)
  • LDL cholesterol calculated using Friedewald formula
  • Anthropometric measurements (weights taken before and after, heights taken at baseline) followed standard procedures etc,
  • BP (seated) and heart rate measured using standard procedure.

Independent Variables

DHA: Rich oil.

Control Variables

Placebo: Olive oil.

Description of Actual Data Sample:

Initial N

  • 114 healthy vegetarians (87 females, 27 males)
  • DHA group had 44 females, 15 males; placebo group had 43 females, 12 males.

Attrition (Final N)

  • Final N: 106 in analysis
  • Two participants dropped out: (one from each group) during intervention
  • Five in the DHA group and one from the placebo group were excluded from analysis.

Age

18 to 43 years.

Ethnicity

None disclosed.

Other Relevant Demographics

  • BP
    • Mean systolic for DHA: 98
    • Mean systolic for placebo: 96
    • Mean diastolic for DHA: 67
    • Mean diastolic for placebo: 67.
  • Years on vegetarians diet
    • DHA: 9.8 years
    • Placebo: 8.8 years.
  • Heart rate (beats per minute)
    • DHA: 67
    • Placebo: 67.

Anthropometrics

BMI (kg/m2)

  • DHA group: 21.4
  • Placebo: 21.2
  • P=0.532.

Location

Munich.

Summary of Results:
  • Median days for the study was 56 (range 56 to 60 days)
  • Compliance was judged by capsule count
    • DHA: 98±2
    • Placebo: 99±2
    • P>0.05.
  • Side effects reported and included skin reactions, flatulence, stomach ache, diarrhea and belching
    • DHA: 11
    • Placebo: 8%.
  • Baseline intakes of EPA and DHA: Median 23 for DHA; median 23 for placebo. It did not change in either group during the intervention.
  • Bodyweight, BP and heart rate did not differ significantly between groups at baseline and changes from baseline were not significant. Examination within group showed a significant increase of systolic BP in the placebo group. A similar trend was observed for the DHA group, but it was not significant (P=0.066).
  • Body weight and BMI increased significantly by 0.5kg or 0.2kg/m2 in placebo group
  • Fatty compositions of erythrocyte total lipids, phosphatidylcholine and phosphatidylethanolamine as well as plasma phospholipids were not different between groups at baseline and changed negligibly in the placebo group
  • After DHA supplementation, no change or little increase was observed for saturated fatty acids (16.0 and 18.0)
  • The MUFA decreased significantly from baseline (P<0.001) in DHA group
  • Microalgae supplementation resulted in significant (P<0.001) increases of EPA and DHA levels from baseline. 

     

  DHA Group (N=53) Placebo Group (N=53)
Between Group Differences
(P-Value)
Week 0 Week 8 P-Value Week 0 Week 8 P-Value
Mean (SEM) Mean (SEM) Mean (SEM) Mean (SEM)
TG (mmol/L)
108 (0.07)
0.83 (0.04)
<0.001
1.07 (0.06)
1.07 (0.07)
0.977
0.034
Total Cholesterol
(mmol/L)
4.58 (0.13)
4.85 (0.14)
0.001
4.72 (0.13)
4.69 (0.12)
0.623
0.004
LDL-C(mmol/L)
2.45 (0.10)
2.71 (0.11)
<0.001
2.56 (0.11)
2.54 (0.10)
0.764
0.003
HDL-C (mmol/L)
1.65(0.06)
1.77 (0.06)
0.002
1.67 (0.06)
1.66 (0.06)
0.487
0.002
LDL:HDL-C
(mmol/L)
1.58(0.07)
1.64 (0.08)
0.180
1.64 (0.09)
1.65 (0.09)
0.798
0.441
Tot : HDL-C
(mmol/L)
2.92(0.10)
2.87 (0.09)
0.485
2.95 (0.10)
2.97 (0.11)
0.790
0.486
TG:HDL-C
(mmol/L)
0.75(0.08)
0.51 (0.04)
<0.001
0.69 (0.05)
0.70 (0.06)
0.733
0.022

Other Findings

  • Absolute alpha tocopherol levels as well as adjusted levels for cholesterol, TG and the sum of cholesterol and TG were not different between groups at baseline and did not change in the placebo group
  • No changes in alpha tocopherol levels and lipid adjusted concentrations of alpha-tocopherol levels after DHA supplementation
  • Supplementation of DHA-rich oil did not result in any physiologically relevant changes in hematology and blood chemistry.
Author Conclusion:
  • Results showed that supplementation with 0.94g per day DHA for eight weeks significantly lowered TG in normolipidemic subjects
  • HDL concentrations increased after eight weeks of DHA supplementation
  • Plasma TG and HDL cholesterol of all subjects at baseline were inversely correlated with HDL cholesterol (P=0.033) and absolute changes in TG correlated inversely with HDL after DHA supplementation (P=0.025).

Conclusion

  • Eight-week supplementation with DHA-rich microalgae oil was associated with improvements in some CHD risk factors (plasma TG, TG to HDL cholesterol ratio) but others, notably LDL cholesterol worsened
  • Therefore the overall effects of this treatment on CHD risk are unclear and should be further investigated.
Funding Source:
Industry:
Reviewer Comments:
  • This study was well designed and very focused. Very positive in terms of strengths. Very detailed descriptions were provided on the methods used for analyzing the labs, diet and anthropometrics.
  • In terms of weakness, I would have liked a little description on the blinding procedures
  • Overall good study.
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? 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? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  3. Were study groups comparable? Yes
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
  3.1. 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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? 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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? 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
  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. 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
  5.1. 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
  5.2. 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
  5.3. 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
  5.4. 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
  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. 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
  6.1. 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
  6.2. 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
  6.3. 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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)? No
  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)? No
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  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
  8.6. 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? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? No
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes