Vegetarian Nutrition

VN: Adolescence (2009)

Citation:

Larsson CL, Klock KS, Astrom AN, Haugejorden O, Johansson G. Food habits of young Swedish and Norwegian vegetarians and omnivores. Public Health Nutr. 2001; 4: 1,005-1,014.

PubMed ID: 11784414
 
Study Design:
Mixed method cross-sectional study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

The purpose of this study was to determine the prevalence of vegetarianism and compare the food habits of different vegetarian and omnivorous adolescents in Sweden and Norway.

Inclusion Criteria:

Ninth grade students in municipal senior secondary school classes in Umea and Stockholm, Sweden and Bergen, Norway.

Exclusion Criteria:

No exclusion criteria was noted.

Description of Study Protocol:
  • Recruitment: In Sweden, subjects were recruited by random selection of ninth grade classes of municipal senior secondary schools in two cities. In Norway, 11 of 24 schools were randomly drawn from one municipality and the ninth grade students from those schools were subjects.
  • Design: This was a cross-sectional study which used a questionnaire to gather information about food habits of the subjects
  • Blinding used: Not applicable
  • Intervention: Survey administration
  • Statistical analysis: Comparisons between dietary groups were made separately for both genders and for each of the vegetarian groups compared with the omnivores by Pearson's Chi Square, Fisher's Exact Test and Mann-Whitney non-parametric U-test.  A two tailed P-value of less than 0.05 was considered statistically significant.
Data Collection Summary:

Timing of Measurements

The food frequency time reference was within the 12 months preceding the administration of the questionnaire.

Survey Tool

  • Questionnaire had 45 food habit questions for the Swedish and 35 food habit questions for the Norwegians, with 35 questions being identical
  • Two identical food habit questions were regarding eating breakfast with family and eating dinner with family
  • Thirty-three questions were regarding food frequencies. All answers could be converted to "consumption frequency of an item per month."
  • Subjects were classified as either vegetarian or omnivore based on dietary intake patterns
  • Study vegetarians were defined as any of the following three sub-classifications:  
    • Semi-vegetarian (lacto-ovo-fish-vegetarian)
    • Lacto-ovo- or lacto-vegetarian
    • Vegan.

Dependent Variables

This was a descriptive study.

Independent Variables   

This was a descriptive study. 

Description of Actual Data Sample:
  • Initial N: N=2,042 (578 from Umea; 504 from Stockhom; 959 from Bergen)
  • Attrition (final N): Not applicable
  • Mean age: 15.5 years
  • Ethnicity: Not identified
  • Other relevant demographics: None noted
  • Anthropometrics: There were no differences in age, weight or height among respondents with different diets or from different cities
  • Location: Umea, Sweden; Stockholm, Sweden and Bergen, Norway.

 

Summary of Results:

 Prevalence of Vegetarians

Prevalence of Vegetarianism in Adolescents in Umea, Stockholm and Bergen, Eating Various Types of Vegetarian Diets in 1996

 

Prevalence %

 

Umea1

Stockholm2

Bergen3

Type of vegetarian diet

Males

N=263

Females

N=293

Total

N=578

Males

N=253

Females

N=244

Total

N=504

Males

N=501

Females

N=451

Total

N=950

Vegan (percent) 1.1 5.5 3.3 0.4 0.4 0.4 0 0.2 0.1

Lacto- and lacto-ovo-vegetarian  (percent)

4.6 13.0 8.8 1.2 2.5 1.8 1.4 1.3 1.4
Semi-vegetarian(percent) 0.8 3.1 3.5 0.8 4.1 2.6 2.2 2.4 2.3
Total (all) vegetarian (percent) 6.5 25.0 15.6 2.4 7.0 4.8 3.6 4.0 3.8
1 Information about gender was missing for 22 omnivores.    2 Information about gender was missing for one semi-vegetarian and six omnivores.    3 Information about gender was missing for seven omnivores. 4 Lacto-ovo-fish-vegetarian.                                                                                    

  • There was a higher prevalence of vegetarianism (P<0.01) in Umea than in Stockholm or Bergen           
  • Lacto-ovo-vegetarians were the most common vegetarians (8.8%), but in Stockholm and Bergen the most common vegetarians were semi-vegetarians   
  • There was a higher percentage of females in Umea and Stockholm, but there were no gender differences in Bergen.       

Attitudes, Dietary Knowledge and Meal Habits of Vegetarians 

  • Young vegetarians wanted to find out more about healthy eating than did the omnivores and preferred to get that information from school and the media
  • Male vegetarians obtained most of their knowledge about diet from newspapers, magazines and brochures compared with male omnivores
  • Female vegetarians perceived their dietary intake to be inadequate more often than did female omnivores and their main reason for taking dietary supplements was to prevent any nutritional deficiency
  • Some vegetarians ate school lunch more frequently than omnivores, but there were some who ate it less frequently
  • § Vegetarians ate breakfast and dinner less often with their families than did the omnivores and more vegetarians than omnivores did not eat any breakfast at all
  • Semi-vegetarians wanted more information about a healthy diet than did the omnivores and they took supplements to prevent nutritional deficiency
  • Lacto-ovo-vegetarians perceived their dietary intake to be inadequate
  • Lacto-ovo-vegetarians wanted to find out more about healthy eating than omnivores and preferred to get that information from school or newspapers, magazines and brochures
  • § Lacto-ovo-vegetarians ate breakfast with their family less frequently or not at all and ate dinner with their family less frequently than the omnivores
  • Vegans believed a healthy diet is important for maintaining good health and took supplements to prevent deficiencies
  • Vegans' main source of diet information was newspapers, magazines and brochures
  • Vegans ate other cooked meals, candies or nothing at all instead of school meals more often than the omnivores
  • Vegans ate dinner without company of family members or not at all more often than the omnivores.

§Indicates identical question regarding this topic was on all questionnaires.

Frequency of Food Intake

  • Vegetarian males largely excluded animal products but showed no other major differences from omnivorous males except they ate margarine, ice cream, cake/cookies and fried and barbecued food less often than did the omnivore males
  • Female vegetarians less often ate potatoes, soft drinks, chips/peanuts, cakes/cookies, fried foods and barbecued food and more often ate rice/pasta, vegetables, coffee, tea, dietary supplements and microwave-heated food than did the female omnivores
  • Semi-vegetarians ate fried potatoes, bread, margarine, soft drinks, chips/peanuts, ice cream, cakes/cookies, fast foods and barbecued food less often than did their omnivorous peers
  • Semi-vegetarians ate fish, vegetables and dietary supplements more often than omnivores
  • Lacto-ovo-vegetarians ate eggs, soft cheese, milk, sour milk/yogurt, potatoes, fried potatoes, porridge, soft drinks, chips/peanuts, fried food and barbecued food less often than the omnivores
  • Vegans ate potatoes, cereals, soft drinks, cakes/cookies and barbecued food less often than did omnivores
  • Vegans and lacto-ovo-vegetarians ate rice/pasta and vegetables, drank tea and took dietary supplements more often than omnivores.

Food Intake of Different Types of Vegetarians Compared to Omnivores

Arrows indicate a statistically significant difference between vegetarian groups and omnimoves in frequency of food items eaten/ month.

Red arrows indicate vegetarian intake is significantly lower than omnivores.

Green arrows indicate vegetarian intake significantly higher than omnivores.

A "♦" symbol indicates that there was no statistically significant relationship.

 

Semi-vegetarians

Lacto- or Lacto-ovo-Vegetarians

Vegans

Sausage

Pork (chops, bacon, ribs)




Poultry

Fish

Seafood (except fish)

 

Eggs

 ♦

 

Cheese

 ♦

 ♦

Soft cheese

 ♦

Milk

 ♦

Sour milk/yogurt

 ♦

 

Rice/pasta

 ♦

 

Potatoes (boiled, baked, mashed)

 ♦

Fried potatoes

 

 ♦

Vegetables (except potatoes)

 

Fruits and berries

 ♦

Porridge

 ♦

Cereal

 ♦

Bread (all kinds)

Margarine

 ♦

 ♦

Coffee

 ♦

Tea

 ♦

 

 

Soft drinks

Diet soft drinks

 ♦

Alcoholic beverages

 ♦

Chips/peanuts

 

 

 ♦

Ice cream

 

 ♦

 ♦

Cakes, cookies

 

 ♦

 

Sweets, chocolates

 ♦

Fast food

 

 ♦

Fried food

 ♦

 

 ♦

Barbequed food

 

 

 

Microwave heated food

 ♦

Dietary supplements

 

 

 

 

Author Conclusion:
  • The food habits of the young group of vegetarians covered a wide range of eating styles and differed from the food habits of omnivorous adolescents
  • In some respects these food habits differed from what has previously been published about vegetarians
  • It remains to be seen whether the health benefits shown in previous studies of vegetarians will apply to the new generation of vegetarians, as they grow older.
Funding Source:
Not-for-profit
1
Foundation associated with industry:
Reviewer Comments:
  • This study appeared to be two similar studies merged and reported as one. They differed in sampling selection and the number of questions in the survey tools (i.e., the Swedish subjects were asked to answer ten more questions concerning attitudes, dietary knowledge and meal habit characteristics). 
  • The cluster sampling used could result in sampling error. The author acknowledged that the high prevalence of vegetarianism in Umea may have been due to the strong local influence of the Straight Edge philosophy and different animal liberation organizations, which advocate for vegetarian diets.
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) N/A
  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) N/A
  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) N/A
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
 
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? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  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? No
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? 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? No
  2.2. Were criteria applied equally to all study groups? No
  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? No
3. Were study groups comparable? No
  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? N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) 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? 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? Yes
  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.) No
  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.) No
  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? N/A
4. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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%.) N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  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? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) N/A
  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.) N/A
  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? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.6. 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? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  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? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? N/A
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? No
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? No
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  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? No
  7.7. Were the measurements conducted consistently across groups? No
  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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  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? 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