Watermelon Serves Up Medically Important Amino
Acid By Erin
Peabody March 21, 2007
Nothing says you care like the gift of a small watermelon. At least
that's the custom in China, where the offer of this red-fleshed cucurbit is
considered a fine way to please a gracious host or ill friend.
Now scientists with the Agricultural Research Service (ARS) have found that there's far more to
this gastronomic gesture than just tradition and good taste. In addition to
containing plentiful amounts of the health-promoting antioxidant lycopene,
watermelon is an excellent source of the amino acid citrulline.
And ARS researchers in Lane, Okla., and their collaborators have found
that not only are watermelon's citrulline stores abundant--they're also readily
usable. Their findings are reported in the current issue of the journal Nutrition.
The human body uses citrulline to make another important amino
acidargininewhich plays a key role in cell division, wound healing
and the removal of ammonia from the body.
ARS plant physiologist
Perkins-Veazie and nutritionist Julie Collins were interested in finding
out just how bioavailable watermelon's citrulline is, since the fruit is one of
few foods to contain high levels of it. Perkins-Veazie works at the
South Central Agricultural Research Laboratory in Lane, while
Collinspreviously based at the Lane laboratoryworks at
Eastern Oklahoma State College in Wilburton.
The two collaborated with amino acid expert Guoyao Wu at
Texas A&M University in College Station.
After analyzing the arginine levels of volunteers who'd recently
consumed differing amounts of concentrated watermelon juice, the scientists
determined that ingesting the juice increased the volunteers' levels of plasma
argininelikely from conversion of citrulline.
Medical researchers are currently evaluating arginine as a possible
treatment for high blood pressure, elevated glucose levels and the vascular
complications associated with sickle-cell disease.
If such studies pan out, concentrated forms of watermelon could
represent an all-natural amino acid source. The fruit's good-for-the-body
lycopene is an added bonus.
Perkins-Veazie is now focused on finding an optimal way of extracting
citrulline from watermelon.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.