Effect of omega-3 fatty acid-containing phospholipids on blood catecholamine concentrations in healthy volunteers: a randomized, placebo-controlled, double-blind trial.
OBJECTIVE
We previously reported that administration of fish oil rich in docosahexaenoic acid (DHA) increased the plasma ratio of epinephrine to norepinephrine (NE) at rest in young adults who were under chronic stress and that this effect was achieved mainly through depression of NE. However, not many reports have documented the effects of eicosapentaenoic acid (EPA) and DHA on blood catecholamine levels in healthy humans. Therefore, we performed another intervention study to test their effect on catecholamines with healthy subjects under no chronic stress.


METHODS
Twenty-one healthy young adults (15 men and 6 women) were randomly assigned to an omega-3 group (n = 9) or a control group (n = 12) in a double-blind manner. Twenty capsules of shellfish-derived lipids containing 762 mg of EPA plus DHA per day were administered to the omega-3 group for 2 mo. The controls took the same amount of placebo capsules. Fasting blood samples after a 30-min rest with a catheter in a forearm vein were obtained at the start and the end of the study for catecholamine measurements.


RESULTS
EPA but not DHA concentrations in red blood cells significantly increased in the omega-3 group compared with the control group (P < 0.001). Plasma NE concentrations were significantly decreased in the omega-3 group (from 1.49 +/- 0.39 nmol/L to 1.05 +/- 0.14 nmol/L) compared with the control group (from 1.12 +/- 0.24 nmol/L to 1.39 +/- 0.32 nmol/L) with analysis of covariance (P < 0.001). The differences remained significant (P = 0.01) even after deletion of three subjects in the omega-3 group who had the highest baseline NE values and one in the control group who had the lowest baseline NE value to nullify a significant baseline differences in NE between groups.


CONCLUSIONS
This study demonstrated that EPA plus DHA supplementation lowered plasma NE concentrations in normal volunteers even at the small dose of 762 mg of EPA plus DHA per day. This effect of EPA plus DHA to lower plasma NE concentrations may be important to understand some of the effects of fish oils on diseases.
Hamazaki
Kei
K
Section of Clinical Application, Department of Clinical Sciences, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Japan.
Itomura
Miho
M
Huan
Mingming
M
Nishizawa
Hiroto
H
Sawazaki
Shigeki
S
Tanouchi
Masatoshi
M
Watanabe
Shiro
S
Hamazaki
Tomohito
T
Terasawa
Katsutoshi
K
Yazawa
Kazunaga
K
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D004837:Epinephrine / Q000097:blood; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D005395:Fish Oils; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D010743:Phospholipids / Q000008:administration & dosage / Q000494:pharmacology*; D010919:Placebos
D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D010743:Phospholipids; D010919:Placebos; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D009638:Norepinephrine; D004837:Epinephrine