The omega-3 fatty acids and subconcussive head impacts study is a double-blind, randomized placebo-controlled trial in which the purpose is to determine whether, and to what extent, supplementation with omega-3 fatty acids [docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)] can maintain or promote neural wellbeing against repetitive subconcussive head impacts, specifically soccer headings. This study will also characterize what aspects of brain cellular and physiologic resiliencies are enhanced by supplementation in adult soccer players (aged 18-30 years old). The study involves taking DHA+EPA or placebo, questionnaires, blood draws, brain imaging, tests to evaluate heart function, and soccer headings. A sub-cohort of participants who meet criteria for ADHD diagnosis will be part of exploratory analyses.