Journal Name:
Artery Research
Article Title:
Canola oil decreases cholesterol and improves endothelial function in patients with peripheral arterial occlusive disease - a pilot study.
Date Written:
2008
Volume:
2
Number:
2
Page:
67
Author(s):
Stricker, H.; Duchini, F.; Facchini, M.; Mombelli, G.
Article:
Among the omega-3 PUFAs, plant-based alpha-linolenic acid (ALA) has been used in fewer interventional studies than marine-based omega-3 PUFAs such as EPA (C20:5n-3) and DHA (C22:6n-3). By desaturation and elongation ALA is a precursor for long-chain EPA and, to a lesser extent, for DHA. There is much debate in the literature as to whether ALA confers benefits similar to marine-based omega-3 PUFAs for primary and secondary prevention of cardiovascular disease. The Western diet typically contains much more omega-6 than omega-3 PUFAs, which leads to a non-physiological omega-6:omega-3 balance and to production of interleukin-1, prostaglandins, and leukotrienes. Omega 3 may positively impact endothelial dysfunction, which is closely related to adverse cardiovascular events and is believed to be a good marker of atherosclerosis and cardiovascular disease (CVD). Omega-3 PUFAs may also exert a positive effect on arrhythmia. The objective of this interventional pilot study in patients with chronic peripheral arterial disease (PAD) was to assess the effects of canola (containing ALA) or sunflower oil (containing LA) on surrogate endpoints of CVD, including parameters of atherothrombosis, fibrinolysis, inflammation, blood lipids, endothelial function, and heart rate variability.
Forty patients with PAD supplemented their usual diet with 2 tablespoons/day of canola oil (n=20) or sunflower oil (n=20), containing 2.24 g of ALA or 16.24 g of linoleic acid (LA), respectively, for 8 weeks. Laser Doppler flux (LDF), was assessed at rest and during reactive hyperaemia. Other measurements included parameters of heart rate variability (HRV), markers of plasmatic coagulation, fibrinolysis, platelet activation, inflammation, and lipid and homocysteine levels. The results showed that LDL-cholesterol decreased significantly from 2.74 +/-0.73 to 2.42+/- 0.65 mmol/L with canola oil but not with sunflower oil. The difference in the percent increase of LDF after ischemic challenge significantly increased with canola oil from a median (25th; 75th percentiles) of 75.2% (48.6;161.2) to 151.7% (117.8; 260.0) and with sunflower oil from 157.9% (125.4; 229.8) to 178.6% (127.3; 356.3), whereas a control group did show any change. HRV and other markers did not change.
This study found that a modest amount of canola oil improved endothelial function in patients with stable chronic PAD and reduced total and LDL-cholesterol, even though the subjects were already being treated extensively with anti-aggregants, statins, and vaso-active substances. Similar supplementation with sunflower oil, resulted in no change in serum lipid concentrations; endothelial function was improved to a lesser extent. Neither intervention had an effect on markers of coagulation, fibrinolysis, platelet activation, inflammation, or Hcy. There was no significant change in parameters of heart rate variability and thus no significant change in the sympathovagal balance, although a favorable trend was noted for ALA.
Endothelial dysfunction is an early pathologic marker in subjects with hypercholesterolemia or the metabolic syndrome and is common in patients with clinically overt atherosclerosis. The results of this study found improved endothelial function but the mechanisms are not clear. Prostacyclin, a series 2 prostaglandin produced from omega-6 arachidonic acid, may be present in a relatively higher amount in patients whose diet is rich in ALA. The authors conclude that canola oil may confer cardiovascular protection, most likely by the dual mechanisms of improving endothelial function and lowering LDL-cholesterol. These results point to the need to further examine the impact of ALA on cardiovascular parameters.
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