Conclusions
On the whole, our results strongly corroborate the past
findings in smaller samples of adolescents and young
adults, which have demonstrated that in contrast to
physical health, a vegetarian diet is not associated with
better mental health. Whether compared with a control
group of non-vegetarians matched for important socio-
demographic characteristics, or with non-vegetarians in
general, vegetarians show elevated prevalence rates of di-
verse mental disorders. Importantly, we found no evi-
dence for a causal role of vegetarian diet in the etiology
of mental disorders. Rather, our results are more consist-
ent with the view that the experience of a mental dis-
order increases the probability of choosing a vegetarian
diet, or that psychological factors influence both the
probability of choosing a vegetarian diet and the prob-
ability of developing a mental disorder.