Yet another reason to adopt a vegetarian diet... Rodale reports that a new study in Nutrition Journal finds vegetarians have lower incidence of depression, anxiety, and other mood problems than their meat-eating neighbors.
I say neighbors specifically because the researchers came to this conclusion after studying Seventh Day Adventists, who were split about 4-5 between vegetarians and meat-eaters. Rodale notes that this group was chosen because the nature of the community is such that it is easier to account for external influences than diet coming into play.
The researchers found the vegetarians reported diets significantly lower in EPA and DHA, the omega-3 fatty acids that we get from eating fish, and which many studies have found are a key factor in improving both physical and mental health. So they expected to find the vegetarians would have higher incidences of issues like depression, anxiety, and mood problems. Instead, they found the opposite result. Vegetarians scored lower on depression tests and had better mood profiles than their fish- and meat-eating peers. "While dietary intake of EPA and DHA has an important role in brain function, we found no evidence that the absence of direct intake of these fatty acids in vegetarians adversely affects mood state," the study reports. "These results challenge what is known about the link between dietary fats and brain function and suggest an unrecognized benefit of vegetarian diets."
The researchers note that one factor influencing the results is that not only were the Seventh Day Adventists following a vegetarian diet, but they also made conscious decisions to eat healthily, eating very little processed food, favoring fruits, vegetables, nuts, and oils high in omega-3 alpha-linolenic acids.
The study notes that we shouldn't generalize to say that getting fish-based omega-3 fatty acids aren't also beneficial for your mood. But I'd add that if you can get the same benefits from a plant source as an animal one, choose the plant one.