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L-arginine improves the function of arteries in smokers
New research testing the effects the amino acid arginine on healthy young smokers suggests that a supplement may have substantial benefits.
Twelve smokers were randomly assigned to receive either 7g of arginine three times daily or an inactive placebo over three days. Neither the participants nor the researchers were aware of which supplement was being administered. The researchers were interested in the effects of arginine on the function of endothelial cells, which line the interior of blood vessels, acting as a selective barrier between the interior of blood vessels and their surrounding tissue.
The endothelium, by releasing nitric oxide (NO), promotes blood vessel relaxation (vasodilation) and inhibits inflammation, blood clot formation (thrombosis), and vascular smooth muscle cell proliferation. In the study endothelial function was assessed before, immediately after, and 20 minuites after cigarette smoking; the measure used was flow mediated dilation (FMD, a measure of the extent to which blood vessels relax in response to stimulus). Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) as a measure of arterial wave reflections. Serum soluble intercellular adhesion molecule-1 (sICAM-1), which is involved in inflammation in the artery and the formation of plaques, was measured.
Compared to placebo, L-arginine improved FMD. L-arginine reduced PWV and AIx at both days 1 and 3. L-arginine blunted the acute smoking-induced increase of AIx at both day 1 and day 3, and prevented the smoking-induced elevation of PWV at day 3. Importantly, L-arginine reduced sICAM-1 at days 1 and 3. The authors concluded that "oral L-arginine improves endothelial function and vascular elastic properties of the arterial tree during the acute phase of smoking". The observed benefits of arginine supplementation on cardiovascular function is believed to be related to its role as a precursor of the signalling gas nitric oxide.
Click here to view the study abstract.