Researchers at Benedictine University in Illinois conducted a randomized control trial to determine the eﬀects on mood of consuming a vegetarian diet, compared with an omnivorous diet or a meat-restricted ﬁsh diet. Omnivorous diets are high in arachidonic acid (AA) and research has shown that high intakes of AA can promote changes in the brain that can disturb mood. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fats found in ﬁsh which are thought to improve mood by opposing the negative eﬀects of AA. This study randomly selected thirty nine omnivores and assigned them to either a group consuming meat, ﬁsh and poultry daily (OMN); a group consuming ﬁsh 3-4 times weekly but avoiding meat and poultry (FISH), or a vegetarian group avoiding meat, ﬁsh and poultry (VEG). Mood was tested using the Proﬁle of Mood States questionnaire and the Depression Anxiety and Stress Scales. The study found that the VEG participants, who through the diet reduced their EPA, DHA and AA intakes, had mood scores that improved signiﬁcantly after two weeks whereas OMN and FISH participants had mood scores that remained unchanged. In conclusion, the results of this study suggest that restricting meat, ﬁsh, and poultry may improve some domains of short-term mood states in modern omnivores.
Nutrition Journal 2012 Feb 14;11:9 (Beezhold et al.)