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Nutrition and Health (including climate and ecological aspects)

Effect of microencapsulated watermelon (Citrullus Lanatus) rind on flow-mediated dilation and tissue oxygen saturation of young adults



Watermelon rind (usually discarded by consumers) presents a high L-citrulline content. Given that Lcitrulline is involved in nitric oxide (NO) synthesis, a crucial molecule that regulates vascular function, this study aimed to evaluate the effect of microencapsulated watermelon rind (MWR) on endothelial function and tissue oxygen saturation (StO2) assessed by flow-mediated dilation (FMD) and near-infrared spectroscopy, respectively. Plasma L-arginine and L-citrulline were also evaluated.


Eleven participants ingested 30 g of MWR (containing 4 g of L-citrulline) and a placebo. Before and 30, 60, 90, and 120 min after ingestion, StO2 parameters were assessed, whereas FMD and plasma amino acids were analyzed 60 and 120 min after ingestion.


The FMD improved 60 min after MWR without changes in StO2 parameters. Absolute plasma L-citrulline and relative change from baseline in plasma L-arginine increased 60 min after MWR ingestion.


A single dose of microencapsulated watermelon rind containing 4 g of L-citrulline seems adequate to improve FMD response, but not StO2 parameters in healthy adults. (NCT04781595).

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Fig. 1: Plasma amino acids before and after microencapsulated watermelon rind and placebo ingestion.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.


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MV-S and GVO acknowledge the financial support provided by CAPES (Brazil) and FAPERJ (E-26/200.021/2020), respectively. Dr. Thiago S. Alvares was supported by FAPERJ Young Scientist Grant Program (E-26/202.905/2019) and by National Council for Scientific and Technological Productivity Scholarship (304189/2020-0).


This work was supported by the Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro – FAPERJ (SEI-260003/001179/2020 and SEI-260003/016456/2021).

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Authors and Affiliations



Conceptualization: TSA, MV-S, GVO. Data curation: MV-S. Formal analysis: MV-S. Funding acquisition: TSA. Investigation: MV-S, GVO and TSA. Methodology: TSA, MV-S, GVO. Project administration: MV-S. Resources: TSA. Supervision: TSA and CACJ. Visualization: MV-S. Writing – original draft: MV-S. Writing – review & editing: TSA and CACJ.

Corresponding author

Correspondence to Thiago Silveira Alvares.

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The authors declare no competing interests.

Ethical approval

This clinical trial was conducted according to the principles established in the declaration of Helsinki and was approved by the Ethics Board of the University of Rio de Janeiro (protocol no. 4.389.357) and the Clinical Trials Registry (NCT04781595).

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Volino-Souza, M., de Oliveira, G.V., Conte-Junior, C.A. et al. Effect of microencapsulated watermelon (Citrullus Lanatus) rind on flow-mediated dilation and tissue oxygen saturation of young adults. Eur J Clin Nutr 77, 71–74 (2023).

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