EFFECTS OF DIETARY SUPPLEMENTATION WITH N-3 POLYUNSATURATED FATTY-ACIDS ON SYMPATHETIC AND HEMODYNAMIC-RESPONSES TO STRESS IN MAN

This paper reports on a preliminary investigation on the effects of dietary supplementation with marine oils on haemodynamics and noradrenaline kinetics in man, both at rest and during mental and physical activity. Healthy male volunteers were treated for 1 month with 20 g/day maxEPA (n=11) or placebo (n=8) in a parallel study design. Total body (all subjects) and cardiac (coronary sinus sampling, maxEPA n=5; placebo n=3) sympathetic activity was assessed by isotope dilution following infusion of tritiated noradrenaline to steady state. Each subject was studied before and after 1 month's treatment. MaxEPA decreased resting supine systolic blood pressure from 140.0 to 133.4 mmHg (SED=2.66, P=0.04). Systemic noradrenaline spillover at rest was unaffected (mean before and after maxEPA: 3.67 and 3.37 nmol/min, SED=0.30). Systolic and diastolic blood pressure, heart rate and systemic noradrenaline spillover (mean before and after maxEPA: 5.42 and 4.04 nmol/min, SED=0.57, P=0.03) during mental stress were all significantly lower after maxEPA. Cardiac noradrenaline spillover during mental stress also decreased in four of four subjects following maxEPA. Neither blood pressure nor noradrenaline spillover during aerobic cycling was affected by maxEPA. Placebo treatment had no effect on any of the parameters measured. It is concluded that dietary enrichment with marine oils lowers systolic blood pressure at rest and particularly during mental exertion, but is without effect during aerobic exercise. Sympathetic activity following mental exertion was lower following maxEPA treatment and may contribute to its hypotensive action at this time.