Vegetarianism and mental health: longitudinal evidence in the 1970 British Cohort Study.

BackgroundReducing 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 birth cohort in Great Britain. MethodsWe use data from the 1970 British Cohort Study, which collected information on diet at age 30 (n = 11,204) and psychological distress (PD) using the nine-item Malaise Inventory at ages 26, 30, 34, 42, and 46-48. We first developed a statistical adjustment strategy by regressing PD at age 30 on vegetarianism and 14 potential confounders measured at ages 10 and 26 (including PD at age 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. Models were reproduced using red meat consumption at age 30 as a sensitivity analysis. ResultsAt 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 yielded similar findings. ConclusionIn 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.