According to a study published this month in Nutrients, researchers investigated the effects of citrulline supplementation on endothelial function and blood pressure in hypertensive postmenopausal women.

Citrulline is an amino acid that is converted to arginine in various cells. Unlike arginine, citrulline is not metabolized in the intestine or liver and does not induce tissue arginase. It inhibits arginase, and citrulline entering peripheral tissues, specifically the kidneys and vascular endothelium and may be readily converted to arginine, thus raising arginine levels, and enhancing nitric oxide production.

Studies have shown that citrulline raises plasma arginine levels significantly higher than arginine itself and has a longer half-life in the body, so citrulline can be thought of as a potent “time-released arginine.”

Aging and menopause are associated with a reduced nitric oxide bioavailability due to reduced L-arginine levels that leads to endothelial dysfunction. This precedes arterial stiffness as well as hypertension development.

 This randomized controlled trial investigated the effects of L-citrulline supplementation on endothelial function, aortic stiffness, and blood pressures in hypertensive postmenopausal women. This study included 25 postmenopausal women between the ages of 50 to 74 years of age that were randomized to take wither 4 weeks of L-citrulline at 10 grams per day or a placebo. Assessments included serum L-arginine, brachial artery flow-mediated dilation, aortic stiffness, and blood pressure measured at baseline and 4 weeks later.

As a result, the L-citrulline supplementation group showed increased L-arginine levels and brachial artery flow-mediated dilation compared to the placebo. In addition, the resting aortic diastolic blood pressure and mean arterial pressure were significantly decreased after 4 weeks of L-citrulline supplementation compared to placebo.

In conclusion, these findings demonstrate that L-citrulline supplementation improves endothelial function and blood pressure by increasing L-arginine availability. Other nutrients to consider include magnesium, taurine, and L-arginine.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Maharaj A, Fischer S, et al. Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women. Nutrients. 2022 Oct 20;14(20):4396.

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