Want Citrulline? Try Watermelon

Watermelon's citrulline seems readily available for the body to take up and use. That's suggested in studies by scientists currently or formerly at the ARS South Central Agricultural Research Laboratory, Lane, Okla.

They did the work with co-investigators from the ARS Henry A. Wallace Beltsville (Md.) Human Nutrition Research Center; the ARS Citrus and Subtropical Products Research Laboratory, Winter Haven, Fla.; and several universities, documenting their work in the journal Nutrition (volume 23, pages 261 to 266).

Volunteers in the study completed one three-week stint during which they drank about three eight-ounce glasses of watermelon juice every day, and one three-week period of drinking about twice that much of the juice daily.

For comparison, other volunteers neither drank the juice nor ate watermelon or certain other foods that would skew study results.

Blood levels of arginine, synthesized in the body from the citrulline provided by the watermelon juice, were 11 percent higher in volunteers tested after three weeks on the three-glasses-a-day regimen (24 ounces), and 18 percent higher following the six-daily-glasses regimen (48 ounces), when compared to levels in samples from volunteers who didn't drink the melon juice.

Now, the scientists want to determine the best way to extract citrulline from watermelon. Preliminary results of medical research—done elsewhere—suggest that arginine might help treat high blood pressure, unhealthy blood sugar levels and vascular disorders associated with sickle-cell disease.