As a fellow vegetarian, this was my first thought as well. I don't think this paper can be taken as sufficient evidence to rule out nutritional deficiencies th

As a fellow vegetarian, this was my first thought as well. I don't think this paper can be taken as sufficient evidence to rule out nutritional deficiencies that could contribute to mental health issues (e.g., decreased B vitamins, iron, vitamin D, tryptophan, etc). I know that when I diligently take these kinds of supplements, I do have more energy and sleep better. However, the "humans are destroying the world" sad feelings that drove me to stop eating meat persist, making me wonder if this is quite confounded relationship.