Lt. Col. Daniel Johnston, an Army doctor serving in Iraq with the Enhanced Combat Aviation Brigade, 1st Infantry Division holds up an omega-3 capsule. Johnston received approval from an Army medical review board to conduct a study in Iraq on whether omega-3 supplements can improve soldiers' mental resilience. Johnston proposed the study after his analysis of soldiers' diets in Iraq revealed significantly low levels of the omega-3 nutrient, which is an essential nutrient linked to vascular and mental health.