Vegetarian Nutrition

VN: Obesity (2009)

Citation:

Marniemi J, Seppänen A, Hakala P. Long-term effects on lipid metabolism of weight reduction on lactovegetarian and mixed diet. Int J Obes. 1990 Feb; 14 (2): 113-125.

PubMed ID: 2111292
 
Study Design:
Randomized controlled trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To examine the effect of two types of dietary regimens (lactovegetarian and mixed diet) on weight loss and blood lipid profiles.

Inclusion Criteria:
  • Between 30% and 50% overweight
  • Age 25 to 50 years
  • No other diseases.
Exclusion Criteria:

Not meeting the inclusion criteria.

Description of Study Protocol:

Recruitment

Subjects recruited from advertisements in local papers.

Design

Randomly assigned by age, sex and weight to one of three groups:

  • Lactovegetarian (1,200kcal per day)
  • Mixed diet (1,200kcal per day)
  • Control diet.

Subjects were asked not to change their exercise habits and a seven-day exercise log was kept at the beginning, at six months and at 12 months to control for exercise.

Diet Intervention

Both intervention diets were energy deficit (1,200kcal per day). Nutritionists recommended:

  • Mixed diet low in fat and sugar and high in fiber and vegetables with moderate fish, meat and eggs. With percent of energy:
    • 25-30% protein
    • 25-30% fat
    • 45-50% carbohydrates.
  • The lactovegetarian diet was similar except without meat, fish or eggs. Low-fat dairy products were allowed and more vegetables were recommended. With percent of energy:
    • 20-25% protein
    • 20-25% fat
    • 55-60% carbohydrates.

Intervention diet groups were divided into three groups of ten subjects each. These groups met once a week for ten weeks and then had five more sessions for the rest of the year. Meetings included nutrition education and food preparation classes.

Blinding

None reported.

Statistical Analysis

Intragroup changes were tested using a T-test. Correlations were obtained using linear regression.

Data Collection Summary:

Timing of Measurements

Fasting blood samples were taken at baseline, two weeks, six weeks, 10 weeks, six months and one year.

Dependent Variables

  • Body weight
  • Body composition (average of three measures of triceps and subscapular skinfolds)
  • Total cholesterol
  • HDL and HDL fractions
  • Triglycerides
  • Apolipoprotein-A and apolipoprotein-B
  • Serum lecithin: Cholesterol acyltransferase
  • Post-heparin plasma lipoprotein lipase
  • Hepatic lipase
  • Adipose tissue LPL and DNA.

Independent Variables

Diet (lacovegetarian or mixed diet).

Control Variables

  • Exercise
  • Sex.
Description of Actual Data Sample:
  • Initial N: 136
  • Attrition (final N)
    • Lactovegetarian group: 31 (23 women, eight men)
    • Mixed diet: 37 (27 women, 10 men)
    • Control group: 42 (32 women, 10 men).
  • Age: Mean 38 years
  • Ethnicity: Not reported
  • Anthropometrics
    • Mean 38% overweight for total sample
    • Mean BMI: 34.4 for lactovegetarian and control group; 33.6 for mixed diet group (differences were not significant).
  • Location: Finland.
Summary of Results:

Intake

For both intervention diet groups, mean caloric intake decreased from 2,300 kcal per day to 1,300 kcal per day at six months and 1,600 kcal per day at one year.

Weight Outcomes

Body Weight (kg)

Mixed Diet

Lactovegetarian

Control

Between Group Difference

Baseline

98.3±4.3

98.3±5.3

97.1±4.4

NS

Six Months

81.5±3.9

86.5±4.5

98.6±4.5


 

One Year

84.3±3.8

89.1±4.4

98.7±4.3

P<0.001

 significantly lower than baseline, P<0.001

The ratio of subscapular to triceps measurement decreased significantly in women at one year, but not in men.

Blood Lipid Outcomes

The authors presented the changes in blood lipid values in figures. Because of this, absolute values are not given. The table below presents the relative changes (a) within diet group at 10 weeks, and (b) between intervention diet group vs. control at 12 months.

 significantly lower;  no significant difference;  significantly higher
 


 


 

Difference from Baseline at 10 Weeks

Difference from Controls at 12 Months

Mixed Diet

Vegetarian Diet

Mixed Diet

Vegetarian Diet

Total Cholesterol

HDL

 

HDL2

 

 

HDL3

Triglycerides

Apolipoprotein-A

Apolipoprotein-B

Adipose Tissue Lipoprotein Lipase

Serum Total Cholesterol

  • Reached their lowest level for both intervention groups at two weeks and then increased so that at 12 months they were not significantly different from the control group
  • The total cholesterol changes were the same for both intervention diet groups.

HDL

  • The vegetarian diet group HDL reached its lowest point at two weeks, and was significantly lower than the mixed group HDL at both two weeks (P<0.01) and one year (P<0.05)
  • HDL of both intervention diet groups was significantly higher than the control diet at one year
  • HDL2 pattern followed that of the HDL levels, dropping at two weeks and then increasing to one year. Only the mixed diet HDL2 was significantly higher than the control group at one year.
  • HDL3 pattern also followed the HDL pattern (dropping early in the study and then rising to one year). In the case of HDL3, both intervention diet groups were significantly higher than the control group.
  • There was no association between weight loss and rise in HDL level over all, but there was a significant negative correlation between HDL and weight loss among women at one year and a significant positive association for men at one year.

Triglycerides

Triglycerides were significantly lower in both diet groups at two weeks compared to baseline. However, at one year, only the mixed diet group triglyceride levels were significantly lower (P<0.05) than controls.

Author Conclusion:
  • Weight reduction and favorable lipid metabolism responses resulted from a low-calorie dietary program in moderately overweight subjects even months after the end of the program
  • Although the results were positive for both mixed and lactovegetarian diets, the responses to the program appear to be stronger in subjects who followed the mixed diet.
Funding Source:
Other: Not reported
Reviewer Comments:
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? No
  2.4. Were the subjects/patients a representative sample of the relevant population? No
  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? No
4. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? No
  4.1. Were follow-up methods described and the same for all groups? No
  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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? No
  4.4. Were reasons for withdrawals similar across groups? 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
  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. 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? No
  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.) 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.) No
  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? 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
  6.7. 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? No
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
  8.1. 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
  8.2. 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? No
  8.3. Were statistics reported with levels of significance and/or confidence intervals? 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
  8.4. 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? No
  9.2. Are biases and study limitations identified and discussed? No
  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