As a vegetarian of eight years, I can say that a meatless diet did not have any effect on my depressive episodes. I had them before I stopped eating meat, and I

As a vegetarian of eight years, I can say that a meatless diet did not have any effect on my depressive episodes. I had them before I stopped eating meat, and I had them after. So based on my one person anecdata this is correlation (maybe a depressed person tries a lifestyle change to help themselves out of depression) but not causation.