Health-related effects of a vegetarian or vegan diet are known to support parameters positively affecting exercise performance in athletes, whereas knowledge about psyche and wellbeing is sparse. Therefore, the aim of the Nutrition and Running High Mileage (NURMI) Study (Step 2) was to compare Quality of Life (QOL) scores among endurance runners following a vegetarian or vegan dietagainst those who adhere to an omnivorous diet ⁽¹⁾. The study was conducted following a cross-sectional design. A total of 281 recreational runners (159 women, 122 men) completed the WHOQOL-BREF questionnaire consisting of the domains physical health, psychological wellbeing, social relationships and environment, which generates scores on a scale from 4 to 20. It was found that 123 subjects followed an omnivorous diet and 158 adhered to a vegetarian/vegan diet. There were 173 runners who met the inclusion criteria ('NURMI-Runners'), among them 103 half-marathoners and 70 marathoners and ultramarathoners, as well as 108 10 km runners as control group. Men had higher scores than women due to high scores in the physical health and psychological well-being dimensions. Adhering to an omnivorous diet affected environment scores for women and social relationships scores for men. Overall QOL scores were high. The results revealed that endurance runners had a high QOL regardless of the race distance or diet choice. The authors conclude that these findings support the notion that adhering to a vegetarian or vegan diet can be an appropriate and equal alternative to an omnivorous diet.