Four weeks of supplementation with the L-arginine formulation blunted detrimental changes to endothelial function after a high-fat meal, as measured by flow-mediated dilation (FMD), according to data published in the Journal of Nutrition.
Arginine is a precursor for nitric oxide (NO), which has been shown to lower blood pressure, reduce blood clotting and protect against myocardial infarction and strokes.
“[T]his study showed that arginine supplementation, at a dose and in a form mimicking an increase in dietary intake, alleviates endothelial dysfunction in the postprandial state when fasting plasma arginine concentrations were lower,” wrote researchers from AgroParisTech at the Université Paris-Saclay in France.
“Arginine supplementation did not improve fasting endothelial function, but, in line with the principle that the beneficial effects of arginine supplements are most evident when endothelial function is impaired, it did indeed blunt postprandial endothelial dysfunction.”
The endothelium – the thin layer of cells lining the blood vessels – performs many functions including maintaining the suppleness of blood vessels and regulating the activity of neutrophils.
Dysfunction in the endothelium leads to arteries with little suppleness, raising the risk of high blood pressure (hypertension), and arteries that are chronically inflamed, leading to an overabundance of adhesion molecules.
Led by Dr François Mariotti, the researchers recruited 33 healthy overweight people with the hypertriglyceridemic waist phenotype to participate in their randomized, double-blind, 2-period crossover, placebo-controlled trial. Participants were randomly assigned to receive 4.5 grams per day of the sustained-release L-arginine or placebo for four weeks. This was followed by a four week “washout period” before crossing over to the other intervention group. FMD and Framingham reactive hyperemia index (fRHI) – another measure of endothelial function – were assessed after a high-fat meal.
Results showed that, in participants with lower fasting arginine levels at the start of the study, supplementation with the L-arginine resulted in significant blunting of the postprandial decrease in both FMD and fRHI, compared to placebo. No such blunting was observed in people with higher baseline fasting arginine levels, however.
“This is the first study, to our knowledge, to report that the vascular effect of L-arginine supplementation varies depending on background arginine status. Indeed, baseline arginine concentration significantly modified the effects of arginine supplementation,” wrote the researchers.
“In contrast with the mitigated results in the total population, subgroup analysis showed that in participants with lower fasting plasma arginine concentration, SR-arginine supplementation clearly alleviated postprandial endothelial dysfunction, as shown by both endothelial endpoints (FMD and fRHI), and resulted in significantly higher FMD and fRHI values at the end of the postprandial period when compared with the placebo.”
Source: Journal of Nutrition
Published online ahead of print, doi: 10.3945/jn.115.227959
“L-Arginine Supplementation Alleviates Postprandial Endothelial Dysfunction When Baseline Fasting Plasma Arginine Concentration Is Low: A Randomized Controlled Trial in Healthy Overweight Adults with Cardiometabolic Risk Factors”
Authors: A. Deveaux et al.