The effect of docosahexaenoic acid on plasma catecholamine concentrations and glucose tolerance during long-lasting psychological stress: A double-blind placebo-controlled study

We previously found that docosahexaenoic acid (DHA) intake prevented aggres sion from increasing at times of mental stress. In the present study, we in vestigated whether DHA intake modified the plasma catecholamines and cortis ol of medical students during a 9-wk period of final exams. We also investi gated the effects of DHA intake on a 75 g oral glucose tolerance test (oGTT S. Fourteen medical students participated in the present study. They were r andomly allocated to either control or DHA group in a double-blind manner. Subjects in the control group (4 males and 3 females) took 10 control capsu les/d, each capsule containing 280 mg of mixed plant oil, and those in the DHA group (4 males and 3 females) took 10 DHA capsules/d containing 1.5 g D HA for 9 wk, during which subjects underwent more than 20 stressful final e xams. At the start and end of the study, plasma catecholamines (epinephrine , norepinephrine (NE) and dopamine) and cortisol were measured; a 75g oGTT was also performed. There were no intra- or intergroup differences in plasm a glucose concentrations. However, NE concentrations were significantly red uced after DHA administration (-31 %, p < 0.03). The other catecholamines a nd cortisol did not change significantly. The plasma ratio of epinephrine t o NE increased in every DHA subject (+78%, p < 0.02), and intergroup differ ences were significant (p < 0.03). We conclude that these effects of DHA ma y be applied to people under long-lasting psychological stress to prevent s tress-related diseases.