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Title: Watermelon consumption increases plasma arginine concentrations in adults

Author
item Collins, Julie
item WU, GUOYAO - TEXAS A&M
item Perkins Veazie, Penelope
item SPEARS, KAREN - UNIV. NEVADA
item CLAYPOOL, P - OSU, STILLWATER, OK
item BAKER, ROBERT - RETIRED, ARS, FL
item Clevidence, Beverly

Submitted to: Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2007
Publication Date: 3/1/2007
Citation: Collins, J.K., Wu, G., Perkins Veazie, P.M., Spears, K., Claypool, P.L., Baker, R.A., Clevidence, B.A. 2007. Watermelon consumption increases plasma arginine concentrations in adults. Nutrition. 23:261-266.

Interpretive Summary: Watermelon is a good source of citrulline, which is metabolized to arginine, an amino acid needed for heart and immune health. This study was conducted to determine if watermelon juice increases the amount of arginine, ornithine, and citrulline in humans. Subjects (n=12-23/ treatment) consumed a controlled of diet no, low (1g/day), or high (2g/day) amounts of watermelon juice for 3 weeks. Compared to the control treatment, fasting plasma arginine concentrations in subjects increased 11% after 3 wks of the low watermelon amount; arginine and ornithine concentrations increased 18 and 16%, respectively, after 3 weeks of the high treatment. Citrulline concentrations did not increase relative to the control but remained stable throughout the study. These results indicate that watermelon provides natural citrulline and argunine to humans, which may be useful in human health studies.

Technical Abstract: Watermelon is a good source of citrulline, an amino acid that can be converted to arginine in the human body. Arginine helps in cardiovascular and immune health. No studies have been conducted to evaluate plasma arginine response in humans following consumption of citrulline from natural plant sources. This study was conducted to determine if watermelon juice increases fasting concentrations of plasma arginine, ornithine, and citrulline. Subjects (n=12-23/ treatment) consumed a controlled diet and 0 (control), 780 g or 1560 g of watermelon juice/d for 3wks in a crossover design. The treatments provided 1 and 2 g of citrulline/d. Treatment periods were preceded by washout periods of 2 to 4 wks. Compared to the control treatment, fasting plasma arginine concentrations increased 11% after 3 wks of the lower watermelon treatment; arginine and ornithine concentrations increased 18 and 16%, respectively, after 3 wks of the higher watermelon treatment. Citrulline concentrations did not increase relative to the control but remained stable throughout the study. The increased blood concentrations of arginine and ornithine and stable concentrations of plasma citrulline in response to watermelon consumption indicated that the citrulline from this plant origin was effectively converted into arginine. These results demonstrate that plasma concentration of arginine can be increased through intake of citrulline from watermelon.