Background: Research suggests a link between deficiencies in omega-3 long-chain polyunsaturated fatty acids (LCPUFAs) and impulsivity among psychiatric populations. However, this association is less evident in non-clinical populations. As omega-3 LCPUFAs are predominantly sourced through fish consumption, non-fish dieters may be more vulnerable to higher impulsivity. Methods: This cross-sectional observational study explored the association between lower intakes of omega-3 LCPUFA food sources and higher self-reported measures of impulsivity among healthy adults consuming non-restricted, vegetarian, and vegan diets. Results: The results from the validated Food Frequency Questionnaire showed significantly lower estimated omega-3 LCPUFA intakes among vegans and vegetarians when compared with people consuming non-restricted diets. Furthermore, although all groups scored within the normal range of impulsivity measures, vegans scored comparatively higher. Vegans also scored significantly hig