Vegetarian Nutrition

VN: Types and Diversity of Vegetarian Diets (2009)

Citation:

Jabs, D., Devine, C., Sobal, J. (1998). Model of the Process of Adopting Vegetarian Diets: Health Vegetarians and Ethical Vegetarians. Journal of Nutrition Education. 30 (4): 196.

 
Study Design:
Descriptive Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To examine the process of adoption as well as progression into stricter vegetarian diets.

Inclusion Criteria:

Specific inclusion criteria were not provided. Recruitment was done from vegetarian groups and referrals of other individuals who were vegetarians.

Exclusion Criteria:

None disclosed.

Description of Study Protocol:

Recruitment

Half of the participants were recruited from a vegetarian group in western New York State. The other half of participants were recruited via snowball sampling which relies on referrals, ads in the vegetarian group newsletter and recruitment cards provided to group members.

Design

  • Qualitative study using an interpretivist approach.
  • In-depth, semi-structured interviews were used.

Blinding used (if applicable)

None

Intervention (if applicable)

No intervention provided.

Data Analysis

The constant comparative method was used to analyze the data from the transcribed interviews and field notes. Categories and coding scheme developed during data analysis was facilitated by the use of The Ehtnograph Software Package (v.4). Since data analysis was conducted by the primary investigator several techniques were used: 1) peer debriefing, 2) discussion with researchers in the field and 3) member checks to validate the findings and data analysis.

Data Collection Summary:

Timing of Measurements

One in-depth semi-structured interview was conducted. The semi-structured interview aimed to tap into the participants:

  • Experiences in adopting and following a vegetarian diet
  • Reasons for, factors aiding and hindering the process of adopting a vegetarian diet
  • Challenges of being vegetarian
  • Influences on adoption of a vegetarian diet. 

The interview evolved after several pilot tests that allowed the primary investigator to improve clarity and probe for codes that were emerging in previous interviews.

Description of Actual Data Sample:

Initial N

N=19 (13 females, six males)

Age

The majority of participants (n=16) were between the ages of 30 to 59. Only one participant was between 25 to 29 and two were greater than 60 years of age.

Ethnicity

  • European-American (n=16)
  • African-American (n=2)
  • Venezuelan-American (n=1).

Other relevant demographics

  • Education: The majority of participants (n=16) had at least two years of college education. Three participants had less than two years college education but had completed high school.
  • Type of vegetarian diet followed by participants: Almost half of participants (n=7) followed a vegan diet followed by Lactovegetarian diet (n=5). The remaining participants were semi-vegetarians, Pescovegetarians, Lacto-ovo or Pesco-ovo.

Anthropometrics (e.g., were groups same or different on important measures)

None were measured.

Location

Western New York State

Summary of Results:

Findings related to the process of adoption to a vegetarian diet

  • The authors constructed a model depicting the process of adoption that is characterized by two pathways of adoption:
    • Health vegetarians: Their pathway to becoming vegetarians is driven by the perceived health benefits of the diet as well as a perceived threat of disease that was often observed in themselves or persons close to them
    • Ethical vegetarians: Their pathway to becoming vegetarians is driven by the issues related to animal welfare and influenced by transitions in their life
  • Several factors characteristics were identified among each participant according to their process of adoption
    • Ethical vegetarians did not convey a perceived threat of disease nor was health and weight a motivation or influence in their process of adoption
    • The process of adoption was more commonly characterized by an abrupt change in ethical vegetarians and as a gradual change in health vegetarians.

Findings related to the process (progression) of adoption

The authors provide two routes of progress based on the analysis of the data; abrupt change or gradual process of adoption.

The author summarizes the differences between the two types of vegetarians in the following table.
 

Categories
Health Vegetarians
Ethical Vegetarians
Perceived disease threat
Primary motivator
Not important
Animal welfare issue
Adopted progressively
Adoption (sometimes suddenly) then maintenance
Adoption age
Often depends on the health problem of self or another
Youth: Make the food-animal connection
Adult: Animal welfare
Adoption process
Gradual
Abrupt: Child and adolescent,
Gradual: Adult
Life transition
Disease diagnosis
Life event change (e.g., going away to college, divorce, job change)
Information
Diet and health
Animal health
Physical results
Good health and weight
Not important
Physical aversion
Lactose intolerant
Disgust to meat
Progression to vegan
Less likely
More likely

 Regarding transition to vegetarianism among young people:

  • Their shift to vegetarianism tends to be more abrupt—often in relation to an experience of making the connection between meat and the animal from which it comes
  • Because adolescence is a time of defining one’s identity, often in contrast to those around you, the barriers to vegetarianism are interpreted in a different way than they are as an adult. In some sense, it’s “normal” for a teen to rebel or define their values or beliefs in contrast to someone else (for instance, family).
  • Transitions, like going away to college, getting a divorce or being diagnosed with a disease, are frequently times when people change to more vegetarian diets. Life transitions may reduce barriers and, in the case of college, may put them into contact with others who support their choices.
Author Conclusion:

Information from this study and other resources can be used by nutrition educators to develop and target messages to influence people adopting vegetarian diets. Since this is one of the early studies to focus on the process of adopting a vegetarian diet, other research is needed to verify and develop this model.

Funding Source:
University/Hospital: Division of Nutritional Sciences, Cornell University
Reviewer Comments:

This was a well-conducted qualitative research study that used well-sounded methods of qualitative data analysis and techniques to ensure trustworthiness of the findings. Due to its nature it cannot be generalized to other vegetarians more so since the majority of participants followed a vegan diet.

The findings discussed included factors that served as motivators in the process of adoption as well as influential factors. These factors seemed confusing as whether they were exclusively part of the adoption process or the progress (i.e., abrupt vs. gradual) of the vegetarian diet.

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? 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? 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? 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? No
  2.2. Were criteria applied equally to all study groups? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  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? N/A
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) 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
  3.2. 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? 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? 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? Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? N/A
  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? 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? 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? 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? 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? 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? 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? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  8. Was the statistical analysis appropriate for the study design and type of outcome indicators? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? N/A
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? 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
  8.4. 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