• ཥL-Citrulline (CIT) improved vascular function in subjects with normal-high blood pressure (BP) at baseline. • ཥCIT improved shoulder and lower back experience in subjects with normal-high BP. • ཥCIT reduced blood 3-nitrotyrosine concentrations in all participants and those with normal-high BP. • ཥPrehypertensive range of BP could be a crucial determinant of the vascular benefits of CIT in healthy individuals. • ཥThese findings should guide future research on the mechanisms behind efficacy differences related to BP. Age-related deterioration in vascular function can lead to cardiovascular diseases and other health problems. The effects of L- citrulline on flow-mediated dilation (FMD) and brachial-ankle pulse wave velocity have been reported; however, its effects on vascular function have only been investigated in high-dose studies of patients with angina pectoris and obesity. We hypothesized that low L- citrulline doses may be effective in healthy adults with declining vascular function and that blood pressure range could be a crucial determinant considering its strong influence on vascular function. This study evaluated the effects of relatively low L- citrulline doses on vascular function in healthy participants and compared its efficacy between participants with normal and high-normal blood pressure. We randomized 66 participants to receive 3,000 mg of L- citrulline (n=33; 21% female; age 63±5 years; systolic blood pressure 130±11 mmHg; diastolic blood pressure 80±8 mmHg) or placebo (n=33; 21% female; age 62±5 years; systolic blood pressure 131±9 mmHg; diastolic blood pressure 79±8 mmHg) for 12 weeks. L- citrulline significantly improved FMD (L-citrulline 4.66±0.45%; placebo 3.46±0.37%, p =0.045) at week 12 in participants with high-normal blood pressure at baseline. L-citrulline also significantly improved subjective feelings of low back pain and shoulder stiffness among participants with high-normal blood pressure. Moreover, it significantly reduced blood 3-nitrotyrosine concentrations in the overall study population and in the subgroup with high-normal blood pressure. In conclusion, an improvement in FMD after 12 weeks of low-dose L-citrulline supplementation was observed only among participants who had high-normal blood pressure at baseline, indicating that baseline blood pressure influences the vascular response to L-citrulline. This study assessed the effects of low-dose L-citrulline on vascular function in healthy adults and how baseline blood pressure affects these outcomes. L-citrulline improved flow-mediated dilation and reduced low back pain, stiff shoulders and blood 3-nitrotyrosine concentrations in participants with normal-high blood pressure at baseline, but these effects were not observed in the overall cohort. The findings suggest that baseline blood pressure can influence low-dose L-citrulline effectiveness.
Nogimura et al. (Wed,) studied this question.