Vegetarianism and mental health: Evidence from the 1970 British Cohort Study.

Background: Reducing animal product consumption has benefits for population health and the environment. The relationship between vegetarianism and mental health, however, remains poorly understood. This study explores this relationship in a nationally representative cohort in Great Britain.

Methods: We use data from the 1970 British Cohort Study, which collected information on vegetarianism at age 30 in 2000 (n = 11,204) and psychological distress (PD) at ages 26, 30, 34, 42, and 46-48 in 2016/18. We first developed a statistical adjustment strategy by regressing PD at age 30 on vegetarianism and 14 confounders measured at ages 10 and 26. We then ran multilevel growth curve models, testing whether within-person changes in PD between ages 30 and 46-48 differed by vegetarianism, before and after statistical adjustment.

Results: At age 30, 4.5 % of participants reported being vegetarian. In the cross-sectional models at age 30, vegetarians reported more distress compared with non-vegetarians in bivariate analysis (b = 0.30, 95%CI 0.09, 0.52), but this difference disappeared in the fully-adjusted model (b = 0.02, 95%CI -0.17, 0.21). In the longitudinal models between ages 30 and 46/48, there were no differences in within-person changes in psychological distress between vegetarians and non-vegetarians (p = .723). Sensitivity analyses using red meat consumption yielded similar findings.

Conclusion: In this British cohort, vegetarianism at age 30 was not associated with changes in psychological distress during mid-adulthood. Since psychological distress in early adulthood predicted vegetarianism at age 30, more studies are needed to disentangle the progression of this relationship over the life-course.