Vegetarian Nutrition

VN: Therapeutic Vegetarian Diets and Attrition (2009)

Citation:

Hakala P, Karvetti R. Weight reduction on lactovegetarian and mixed diets. Eur J Clin Nutr. 1989; 43: 421-430.

PubMed ID: 2743965
 
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:

The purpose of this study was to determine the effects of low-energy lactovegetarian and mixed diets on body weight (within a weight-loss intervention), nutrient intake, skinfold thickness and blood pressure.

Inclusion Criteria:
  • Minimum of 30% and maximum of 50% overweight
  • Age 25 to 50 years
  • No limiting disease or medical treatment.
Exclusion Criteria:

No exclusion criteria were noted.

Description of Study Protocol:

Recruitment  

Subjects were approached by placing an advertisement about the study in the local newspaper.

Design     

In this study subjects were randomly assigned according to sex, age and overweight to three groups: Lactovegetarian weight reduction groups (N=46), mixed diet weight reduction group (N=46) and control group (N=44). The lactovegetarian and the mixed diet group participated in a 10-week weight reduction program which recommended individual daily diets of 1,200 calories.

Subjects were asked not to change their physical activity level during the weight loss period.

Blinding Used

No blinding discussed.

Intervention

  • The two treatment groups (lactovegetarians and mixed diet) participated in a 10-week weight reduction program which met as a group once a week. In addition to the nutrition education, each 10-week course had one lecture by a physician, a psychologist and a physiotherapist.
  • A meal pattern of three meals and two snacks was demonstrated and participants were advised to use the diet for one year
  • After the 10-week weight reduction course, the groups had five sessions during the rest of the year to motivate participants and repeat previous diet instructions. 

Statistical Analysis

  • Significance of changes in results in study groups was assessed by the one sample T-test
  • The hypothesis of differences in changes between the groups during six and 12 months were tested by the two sample T-test.
Data Collection Summary:

Timing of Measurements

  • Four-day food diary: before, in the middle, and at end of 10-week weight reduction course, and also six and 12 months after the outset of the study (for the control group, the four-day food diary was only kept at the beginning of the study and six and 12 months later)
  • Height was measured before the weight reduction program started
  • Weight was measured before, in the middle, and at end of 10-week weight reduction course, and also 6 and 12 months after the outset of the study 
  • Triceps and subscapular skinfold thickness was measured; arm circumference was measured and arm muscle circumference was calculated.

Dependent Variables

  • Weight measured to nearest 110 gram on an automatic scale (SECA 708 personal scale)
  • Tricep and subscapular skinfold thickness from the inactive side of the body measured to 1/10mm accuracy with a Harpenden Skinfold Caliper. Skinfolds each measured three times and the means taken.
  • Arm muscle circumference (measured twice and means taken) and arm muscle circumference calculated as 0.314 x triceps skinfold (cm)
  • Systolic and diastolic blood pressure taken from right arm of seated person by the auscultatory method after a minimum of 10-minute rest.

Independent Variables

  • A 1,200kcal lactovegetarian diet (containing no meat fish or eggs)
    • 20-25% protein
    • 20-25% fat
    • 55-60% carbohydrate.
  • A 1,200kcal (low fat and sugar, high fiber and vegetables, and moderate in meat, fish and eggs) 
    • 25-30% protein
    • 25-30% fat
    • 45-50% carbohydrate.

Control Variables

  • Subjects were asked not to change their physical activity during the weight reduction period
  • Exercise level was controlled by weekly exercise records at the beginning of the study and at six and 12 months.
Description of Actual Data Sample:

Initial N

N=136; randomly assigned according to sex, age and overweight to three groups

  • Lactovegetarian: 46
  • Mixed diet: 46
  • Control: 44.

Attrition (Final N)

Total N=110

  • Lactovegetarin group: N=31 (23 female, 8 male)
  • Mixed group: N=37 (27 female, 10 male)
  • Control group: N=42 (32 female, 10 male).

Drop out rate was 33% for lactovegetarian, 20% for mixed diet group, and 5% for the control group.

Age

Mean age: 38 years.

Ethnicity

Not identified.

Other Relevant Demographics

All subjects were subjectively healthy and not on any regular medical treatment.

Anthropometrics: Weight, Height, Body Mass Index and Desirable Weight of Subjects in Each Treatment Group at Beginning of Study

  Lactovegetarian Group (N=31) Mixed Diet Group (N=37) Control Group (N=42)

Weight, kg

98.3±14.9 93.8±13.4 97.1±14.4
Height, cm 169±10 167±8 168±8
Body Mass Index, kg/m² 34.4±3.9 33.6±3.5 34.4±3.8
Desirable Weight Reduction,*  kg -27.5 -24.4 -27.1

*Calculated from the recommended weights for Finnish adult population (Heliovaara and Aromaa).

Location

Finland.

Summary of Results:

Percentage of Subjects who Lost or Gained Weight in the Groups During the Study Year

Weight Loss Lactovegetarian Group (N=31) Mixed Diet Group (N=37) Control Group (N=42)
Percentage
Percentage
Percentage
Over 10kg 42 38 -
Over 5kg and up to 10kg 29 49 7
Under 5kg 19 11 24
Weight Gain 10 2 69
  • Mean weight loss in both treatment groups was statistically significant
  • Both treatment groups lost weight mainly during the 10-week weight reduction classes
  • Almost 70% of the control group gained weight during the study year
  • Lactovegetarians seemed to have difficulty following the diet for long periods and 23% of the group gave up the diet to some extent during the intervention year.

Mean Intake of Selected Nutrients in the Three Groups During the Study Year

Lactovegetarian Group

Zero Months
(N=31)

Six Months
(N=28)
12 Months
(N=21)
Energy, kcal
2,299±537
1,291±279
1,570±566
Protein % Energy
15±2
17±3
17±5
Fat  % Energy
39±6
23±5
25±6
Cho % Energy
43±7
57±8
56±8
Alcohol % Energy
3±6
3±6
2±6
Sucrose % Energy
8±3
7±3
6±3
P to S Ratio
.4±0.2
0.5±0.3
0.4±0.2
Cholesterol, mg
436±174
122±62
180±120
Vitamin A, mcg RE
1,292±929
1,073±583
1,173±697
Thiamine, mg
1.3±0.3
1.1±0.3
1.2±0.3
Riboflavin, mg
2.2±0.7
1.6±0.6
1.9±0.6
Niacin, mg
18.8±8
8±2
11±7
Vitamin C, mg
124±74
169±75
164±83
Calcium, mg
1,066±320
1,049±389
1,163±383
Iron, mg
14.5±3.6
10.4±2.3
11.7±3.0
Fiber, grams
20±8
23±7
25±8
Mixed Diet Group

Zero Months
(N=37)

Six Months
(N=33)
12 Months
(N=29)
Energy, kcal
2,144±799
1,320±392
1,524±492
Protein % Energy
15±3
20±3
17±4
Fat  % Energy
39±6
29±4
32±6
Cho % Energy
44±7
49±7
49±6
Alcohol % Energy
2±3
2±4
2±3
Sucrose % Energy
8±4
6±2
7±4
P to S Ratio
0.3±0.2
0.4±0.2
0.5±0.1
Cholesterol, mg
424±185
272±121
283±114
Vitamin A, mcg RE
996±5.17
1,196±868
994±593
Thiamine, mg
1.4±0.5
1.1±0.3
1.2±0.5
Riboflavin, mg
2.1±0.8
1.6±0.5
1.6±0.5
Niacin, mg
16±7
12±4
14±6
Vitamin C, mg
102±45
116±51
105±46
Calcium, mg
1,017±389
761±227
760±238
Iron, mg
13.8±4.7
11.2±3.8
11.8±3.4
Fiber, grams
19±5
19±6
19±7
Control Group Zero Months
(N=38)
Six Months
(N=38)
12 Months
(N=37)
Energy, kcal
2,113±519
1,893±493
2,045±522
Protein % Energy
14±2
15±3
15±3
Fat  % Energy
39±5
38±6
37±5
Cho % Energy
45±6
45±6
47±8
Alcohol % Energy
2±5
2±6
1±4
Sucrose % Energy
9±4
8±4
8±4
P to S Ratio
0.4±0.2
0.3±0.2
0.4±0.1
Cholesterol, mg
407±139
403±163
386±127
Vitamin A, mcg RE
1,453±1,176
1,083±1,207
1,105±793
Thiamine, mg
1.3±0.3
1.2±0.3
1.3±0.4
Riboflavin, mg
1.9±0.6
1.9±0.6
1.9±0.6
Niacin, mg
17±6
14±5
16±4
Vitamin C, mg
120±54
103±46
104±49
Calcium, mg
847±271
861±263
905±346
Iron, mg
14.1±3.9
12.6±3.8
14.1±4.0
Fiber, grams
20±8
18±5
21±8
  • In the first half of the study, both treatment groups changed their food habits towards the desirable nutritional goals taught in the weight reduction classes
  • At six and 12 months the nutrient density per 1,000kcal had improved in both weight reduction groups
  • At six and 12 months, lactovegetarians were somewhat below recommendations for niacin and iron
  • At six and 12 months, mixed group subjects were somewhat below recommendations for calcium and iron
  • The control group intakes of energy and nutrients remained almost the same throughout the study.

Blood Pressure

Mean systolic and diastolic blood pressure change (mmHg) at one year (systolic/diastolic)

  • Lactovegetarian: -2.5/-1.5
  • Mixed: -6.3/-4.7
  • Control: Unchanged.

Both the lactovegetarian and mixed group means for systolic and diastolic blood pressure decreased significantly compared to the control group.

Triceps Skinfolds (TSF), Subscapular Skinfold,(SSF), Arm Circumference (AC) and Arm Muscle Circumference (AMC) during the One Year Intervention Period
(Means and 95% confidence limits)

  Lactovegetarian Group Mixed Group Control Group
TSF SSF AC AMC TSF SSF AC AMC TSF SSF AC AMC
0 Weeks 27 37 38 29 30 40 37 28 26 38 37 28.5
Six Weeks 23 31 36 28.5 24 35 36 28 26 38 37 28.5
10 Weeks 21 29 35 28.5 21 28 34 27.5 26 38 37 28.5
26 Weeks 21*** 28*** 34.5*** 28** 19*** 25*** 33.5*** 27.5 26 38 37 28.5
52 Weeks 21** 29*** 35***

28.5***

20*** 25*** 34*** 27.5 25 38 37 28.5

Significance of changes in mixed diet and lactovegetarian groups compared to those of the control group at 26 and 52 weeks is as follows: **P<0.01, ***P<0.001.

  • Weight loss was accompanied by a reduction in the skinfold thickness
  • Mean values of skinfold thickness and arm circumference fell significantly in the lactovegetarian and mixed diet groups but remained nearly unchanged in the control group
  • Compared to the starting level the loss of arm muscle circumference was statistically significant in the lactovegetarian group but not in the mixed group.

 

Author Conclusion:

In spite of its sound nutritional characteristics, a well-planned lactovegetarian diet does not have more beneficial effects on the weight, nutrient intake, blood pressure and skinfold thickness of overweight subjects than a balanced mixed diet. For the long-term weight reduction of overweight subjects, it seems to be desirable to recommend a low-calorie nutritionally well-planned mixed diet, based on familiar foods and rich in vegetables, instead of a lactovegetarian diet.

Funding Source:
Other: No funding sources acknowledged
Reviewer Comments:

Although four-day food diaries were kept before, in the middle, and at the end of the 10-week reduction course and also at six and 12 months, there was no assurance that the treatment groups maintained diet recommendations throughout the study year. This would also be true regarding physical activity levels.

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? 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
  4.2. 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? Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? 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
  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? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  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? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? Yes
  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)? N/A
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes