Abstract
Wider adoption and maintenance of vegetarian diets would be mutually beneficial for human and environmental health. Social networks have been identified as a factor that would support this transition. While social networks’ role in vegetarian diet adoption has been studied, their role in vegetarian diet maintenance over time has received much less attention. To address this gap, we investigated the extent to which having vegetarian close ties (family members and/or partners) was related to participants’ likelihood of eating vegetarian. Data were derived from Lifelines, a large cohort study from the northern Netherlands (n = 60,639). Two assessments an average of 3.9 years apart were used. We studied the interaction of close ties’ diet trajectories (either vegetarian or omnivore) at baseline and follow-up, and their relationship to participants’ own diet trajectories at baseline and follow-up. Mixed multinomial logistic regression was used to account for clustering among families. Participants closely mirrored their close ties’ diet trajectories. Having close ties who were vegetarians at baseline and follow-up was associated with the highest probability of the participants themselves also eating vegetarian at both assessments (Pr = 0.08, 95% CI: 0.07-0.08). In contrast, participants with no vegetarian close ties at baseline and follow-up were the least likely to be vegetarians themselves at both assessments (Pr = 0.02, 95% CI: 0.02-0.02). Partners particularly had a strong influence on participants’ diet trajectories compared to other family members. It appears that the closer the tie was, the more closely diet trajectories paralleled each another. More broadly, leveraging social networks could be effective in encouraging more widespread adoption and maintenance of vegetarian diets.
Generated Summary
This research, drawing from the Lifelines Biobank and Cohort Study in the northern Netherlands, investigates the influence of social networks on the adoption and maintenance of vegetarian diets. Utilizing data from a large cohort (n = 60,639) with two assessment points approximately 3.9 years apart, the study focuses on the diet trajectories of participants and their close ties (family members and/or partners). The study employed mixed multinomial logistic regression to explore how the diet choices of close contacts at baseline and follow-up influenced participants’ own dietary habits across the same time frame. The aim was to understand the degree to which having vegetarian close ties was linked to participants’ likelihood of adopting and maintaining vegetarian diets.
Key Findings & Statistics
- The study found that 4.12% of participants were vegetarians at baseline and 4.35% at follow-up.
- The overwhelming majority (94.15%) of participants were omnivores at both baseline and follow-up.
- 2.63% of participants were vegetarian at both baseline and follow-up.
- 1.72% of participants transitioned from omnivore to vegetarian, while 1.50% went from vegetarian to omnivore.
- The study highlights significant differences in socioeconomic characteristics between vegetarians and omnivores.
- Vegetarians: 77.05% of vegetarians were women vs 57.19 % of omnivores.
- Vegetarians: Higher education levels (46.70% high education) compared to omnivores (29.09%).
- Vegetarians: More likely to live in urban areas (13.91%) compared to omnivores (5.39%).
- In terms of health and health-related behaviors:
- Vegetarians: 64.25% were underweight or normal weight.
- Omnivores: More likely to be overweight or obese.
- Vegetarians: Had healthier diets (45.30% in healthiest quintile).
- The study found that participants with at least one vegetarian close tie at baseline and follow-up: 7.45% were themselves vegetarian at both assessments.
- Only 1.78% of participants without a vegetarian close tie were vegetarians.
- The study found that having at least one vegetarian close tie at baseline and follow-up was associated with an 0.08 probability (95% CI: 0.07-0.08) of the participant also being vegetarian at both time points.
- Participants with only omnivorous close ties at both baseline and follow-up had a probability of 0.02 (95% CI: 0.02-0.02) of being a vegetarian.
- The study found that the likelihood of participants being omnivores at both baseline and follow-up was 0.96 (95% CI: 0.96–0.96) if they had only omnivorous close ties.
- Participants with vegetarian close ties at baseline and follow-up had the lowest probability of being omnivores at both points, 0.87 (95% CI: 0.86-0.88).
- Participants whose diets changed were more likely to mirror their close ties’ changes.
- Participants with only omnivorous close ties at baseline and at least one vegetarian close tie at follow-up were most likely to be omnivores at baseline and vegetarians at follow-up, with a probability of 0.04 (95% CI: 0.03-0.05).
- Participants with at least one vegetarian close tie at baseline, but only omnivorous close ties at follow-up had a 0.03 probability (95% CI: 0.03-0.04) of a similar diet trajectory.
Other Important Findings
- Partners’ diet trajectories had a stronger influence on participants than other family members.
- The study indicated that the closer the relationship, the more aligned the diet trajectories were.
- The number of vegetarian close ties did not have a significant effect on the participants’ diet trajectory.
- Partners were identified only if they lived with the participants.
- The study found that the type of close tie mattered: partners most strongly influenced the diet trajectories of participants, while parents and other family members also had an influence.
- The study noted that the amount of exposure to a vegetarian diet, i.e., the number of vegetarian close ties, did not appear to affect the participants’ own diet trajectories.
Limitations Noted in the Document
- The study’s reliance on two fixed time points prevented the ability to determine the exact timing of influence between close ties and participants.
- The study used a simple measure of diet trajectory (vegetarian or not), not accounting for the amount of meat reduction or flexitarianism.
- The study focused only on close, formal ties (partners and immediate family), excluding friends and co-workers.
- Selection bias was present, with the final study sample being older and wealthier than the total baseline sample, which may affect the generalizability of the findings.
- The study was conducted during the 2010s, and the findings might not fully reflect current trends in meat consumption reduction efforts in the Netherlands.
- The study’s setting in the northern Netherlands might not be fully representative of the dietary trends across the whole of the Netherlands.
Conclusion
The study confirms that social networks play a crucial role in the adoption and maintenance of vegetarian diets. It provides evidence that individuals’ dietary habits are significantly influenced by those of their close contacts, particularly partners. The study underscores the importance of leveraging social networks to encourage a broader shift toward vegetarian diets. The findings suggest that supporting and encouraging the establishment and maintenance of vegetarian diets among close ties could be a key strategy in promoting a sustained shift towards such diets. The research highlights that diet trajectories closely mirrored those of their close ties, indicating that the closer the relationship, the more the diets align. Participants with vegetarian close ties at both time points were more likely to maintain vegetarian diets, while those with omnivorous ties were more likely to remain omnivores. For practitioners and policymakers, the research points to the potential of utilizing social networks as a tool for promoting dietary changes. Interventions targeting social ties could be developed to help people adopt or maintain vegetarian diets. This study’s findings are particularly important in the context of the Netherlands, where efforts to reduce meat consumption are gaining prominence. The study also notes, the dose-response relationship might not have been present or fully detected. It suggests that the amount of exposure to a vegetarian diet, measured by the number of vegetarian close ties, did not have a strong influence on participants’ own diet trajectories. This could be because the network was not fully observed.