n-3 fatty acids and urinary excretion of nitric oxide metabolites in humans

Abstract

Fish oils rich in n-3 fatty acids have been shown to augment endothelium-dependent vasodilation in human peripheral and coronary arteries. This suggests that n-3 fatty acids may enhance arterial nitric oxide production. To explore this hypothesis we measured total urinary nitrate output in healthy volunteers supplemented with a fish oil concentrate (FOC; n = 15) or purified eicosapentaenoic acid (EPA; n = 14) in a placebo-controlled, parallel-group study. The FOC contained 41% EPA and 23% docosahexaenoic acid (DHA) ethyl esters, whereas EPA was 91% pure; the placebo contained olive oil ethyl esters. Doses were 5 g placebo, 5 g FOC, and 3 g EPA to keep the total n-3 fatty acid content equal in the latter two groups. The placebo period was 2 wk long and was followed by a 3-wk n-3 fatty acid phase. At the end of each period, 24-h urine collections and fasting blood samples were obtained. Serum and urinary nitrate concentrations were measured in a blinded fashion. The FOC produced a 43% increase in daily, creatinine-adjusted, nitrate excretion rates (P < 0.029). Because serum nitrate concentrations were not different, these findings suggest that FOC supplementation may stimulate systemic nitric oxide synthesis. The lack of effect with EPA supplementation suggests that this component of the FOC is not likely to be an active component. If confirmed, these observations suggest another mechanism whereby n-3 fatty acids may be antiatherogenic.

Protective Effect of Docosahexaenoic Acid Against Cyclosporine A-Induced Nephrotoxicity in Rats: A Possible Mechanism of Action

“…DHA administration was proved to increase the release of endothelium-derived relaxing factor, presumably NO, which facilitates arterial relaxation, decreases blood pressure, improves vascularity, and consequently reduces the kidney function impairment. 17,54 Similar results were reported by Robinson and Stone, 20 who observed that DHA enhanced the formation of NO, which induces its hypotensive effect.…”

“…16 Polyunsaturated fatty acids are known to have potential cardiovascular benefits that include lowering blood pressure and improving vascular tone, whereas their impact on lipid peroxidation has been controversial. [17][18][19][20][21] In view of this, we investigated the ability of DHA to restore the deteriorated renal functions induced by CsA in a rat model. Furthermore, renal tissue nitric oxide (NO) level, lipid peroxidation, protein oxidation, and urinary level of NO were investigated in an attempt to understand the mechanistic basis of the observed DHA activities.…”

The differential effects of EPA and DHA on cardiovascular risk factors

“…NO production (110) . In summary, there are too few data to conclude whether EPA and DHA have differing effects on endothelium-dependent vasodilation, but early indications are that DHA might be more effective in improving EF.…”

Utilization of some vegetable oil blends rich in omega-3 fatty acids:<br>Biological evaluation

“…Vegetable oil rich in the n-6 FAs have been promoted as lowering blood cholesterol concentration of the people in USA (Hass, 1999). Harris (1997) showed that the plant n-3 FA caused rise of LDL-cholesterol by 5-10% and HDLcholesterol by 1-3%. Fickova et al (1998) noticed that rats fed on the diet containing n-3 FA contained significantly lower level serum triglycerides compared with those fed on diets having n-6 FAs.…”