Administration of docosahexaenoic acid influences behavior and plasma catecholamine levels at times of psychological stress

The purpose of the present research waste to clarify the effect of docosahe xaenoic acid (DHA) intake on behavior and plasma catecholamines (CA). In St udy 1, 42 students took either DHA-rich oil capsules containing 1.5-1.8 g D HA/d or control oil capsules containing 97% soybean oil plus 3% of another fish oil for 3 mon in a double-blind fashion. They took a psychological tes t (PF Study) at the start and end of the study. This study started at the e nd of summer Vacation and ended just before the final exams. In the control group, external aggression (aggression against others) in PF Study was sig nificantly increased at the end of the study as compared with that measured at the start (+8.9%) whereas it was ndt significantly changed in the DHA g roup (-1.0%). In a similar double-blind study (Study 2),we measured externa l aggression under nonstressful conditions. External aggression slightly de creased in the control group, whereas there were no significant changes in the DHA group. In Study 3 with 14 students, plasma CA were measured at the start and end of capsule administration period of 2 mon. Subjects were unde r continuous stress of the final exams that lasted throughout the whole stu dy period. The ratio of plasma epinephrine to norepinephrine concentrations was significantly increased in the DHA group (78%), whereas it stayed at t he same level in the control group. In Study 4, mice were fed either DHA-de ficient diet or -sufficient diet for 4 wk, and-their rearing frequency (an anxiety index) was measured. In the DHA-sufficient group, the rearing frequ ency was significantly less than in the other group. These effects of DHA i ntake may be applied to people in an attempt to ameliorate stress-related d iseases.