Nutr Neurosci. 2014 Nov 21. 

Vegans report less stress and anxiety than omnivores.

Beezhold B, Radnitz C, Rinne A, DiMatteo J.


Objective Studies investigating mood in vegetarian diets have yielded conflicting results, either demonstrating risk for mental disorders or mood protection. Our objective was to investigate mood, as well as factors that potentially impact mood in vegans (VG), vegetarians (VEG), and omnivores (OMN). Methods We surveyed mood, diet, and lifestyle factors in a broad geographic online sample of adult VG (n = 283), VEG (n = 109), and OMN (n = 228) who were recruited via diet-related social networks. Mood was measured with the Depression Anxiety Stress Scale-21 (DASS-21). 

Results The sample was mostly female (78.5%), and age was inversely correlated with all DASS scores (P < 0.05). Mean DASS-A (anxiety) and DASS-S (stress) scores differed by group (F(2616) = 4.73, P = 0.009, η2 = 0.015, and F(2, 615) = 8.23, P < 0.001, η2 = 0.026, respectively), with VG scores lower than OMN scores, indicating less mood disturbance. 
Analyses of covariance were conducted by gender, adjusting for age. Anxiety scores were different in males only (F(2128) = 5.39, P = 0.006, ηp2 = 0.078) and lower anxiety in males was related to a vegan diet and daily fruit and vegetable intake. Mean stress scores were different in females only (F(2476) = 3.82, P = 0.023, ηp2 = 0.016) and lower stress in females was related to a vegan diet and lower daily intake of sweets.

Discussion: A strict plant-based diet does not appear to negatively impact mood, in fact reduction of animal food intake may have mood benefits. The improved mood domains were not consistent with those found in other studies, which may be due to methodological differences.