High dose L-citrulline shows cardiovascular benefits for older women: RCT

By Stephen Daniells

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© kate_sept2004 / Getty Images
© kate_sept2004 / Getty Images

Related tags L-citrulline L-arginine Heart health cardiovascular health Blood pressure Postmenopausal women

Daily supplementation with L-citrulline may improve both endothelial function and blood pressure for postmenopausal women, says a new study from Texas Tech University.

The amino acid L-citrulline is said to play an important role in nitric oxide (NO) metabolism and regulation. L-Citrulline is converted to L-Arginine in the body to support L-Arginine and NO levels. Increased production of NO promotes vascular dilation which improves oxygen and blood circulation throughout the body.

New data published in Nutrients​ indicated that four weeks of supplementation with 10 grams per day of L-citrulline did lead to big increases in arginine levels and was associated with statistically significant improvements in flow-mediated dilation (FMD), a measure of endothelial function, and diastolic blood pressure (BP), compared to placebo.

“Oral L-CIT supplementation may be a viable therapeutic strategy to combat the vascular complications that become apparent in hypertensive postmenopausal women,” ​wrote the researchers.

Study details

The Texas-based scientists recruited 25 postmenopausal women with elevated blood pressure (hypertension) to participate in their randomized, placebo-controlled trial. The women were randomly assigned to receive either the L-citrulline supplement (provided by NOW Foods) or placebo for four weeks.

The results showed that serum L-arginine levels increased in the citrulline group by an average 13 µmol/L, compared to a decrease of 2 µmol/L in the placebo group.

FMD increased by 1.4% in the L-citrulline group, compared to a 0.5% decrease in the placebo group.

“To our knowledge, this is the first study to report that L-CIT supplementation improves endothelial function (FMD) in hypertensive, otherwise healthy postmenopausal women, and sheds light on the potential for improving vascular function via a dietary intervention,” ​wrote the researchers.

In addition, resting aortic diastolic blood pressure decreased by an average of 2 mmHg in the citrulline group, compared to a 2 mmHg increase in the placebo group.

“In agreement with our finding, a meta-analysis found that L-ARG supplementation decreases DBP by 2 mmHg in women but not in men,” ​wrote the researchers. “Such decrease in DBP would reduce the prevalence of hypertension by 17% and the risk of heart failure by 6%. The current study found that 4 weeks of L-CIT supplementation reduced DBP to more optimal levels (~80 mmHg) in hypertensive postmenopausal women.”

“Future studies are needed to examine the effects of L-CIT supplementation in other cohorts with known endothelial dysfunction such as obese with cardiometabolic risk factors and type 2 diabetic populations,” ​they added. “Lastly, a longer intervention (≥8 weeks) using the high dose of L-CIT implemented in this study (10 g/day) in a hypertensive population has never been examined and would, in theory, elicit a more robust improvement in both endothelial function and blood pressure.”

Source: Nutrients
2022, 14​(20), 4396; doi: 10.3390/nu14204396
“Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women”
Authors: A. Maharaj, et al.


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