Dietary supplementation with watermelon pomace juice enhances arginine availability and ameliorates the metabolic syndrome in Zucker diabetic fatty rats

J Nutr. 2007 Dec;137(12):2680-5. doi: 10.1093/jn/137.12.2680.


Watermelon is rich in L-citrulline, an effective precursor of L-arginine. This study was conducted to determine whether dietary supplementation with watermelon pomace juice could ameliorate the metabolic syndrome in the Zucker diabetic fatty (ZDF) rat, an animal model of noninsulin-dependent diabetes mellitus. Nine-week-old ZDF rats were assigned randomly to receive drinking water containing 0% (control) or 0.2% L-arginine (as 0.24% L-arginine-HCl), 63% watermelon pomace juice, 0.01% lycopene, or 0.05% citrus pectin (n = 6 per treatment). At the end of the 4-wk supplementation period, blood samples, aortic rings, and hearts were obtained for biochemical and physiological analyses. Feed or energy intakes did not differ among the 5 groups of rats. However, dietary supplementation with watermelon pomace juice or L-arginine increased serum concentrations of arginine; reduced fat accretion; lowered serum concentrations of glucose, free fatty acids, homocysteine, and dimethylarginines; enhanced GTP cyclohydrolase-I activity and tetrahydrobiopterin concentrations in the heart; and improved acetylcholine-induced vascular relaxation. Compared with the control, dietary supplementation with lycopene or citrus pectin did not affect any measured parameter. These results provide the first evidence to our knowledge for a beneficial effect of watermelon pomace juice as a functional food for increasing arginine availability, reducing serum concentrations of cardiovascular risk factors, improving glycemic control, and ameliorating vascular dysfunction in obese animals with type-II diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / drug effects
  • Arginine / blood
  • Beverages
  • Blood Glucose
  • Citrulline / blood
  • Citrullus*
  • Diabetes Complications / drug therapy*
  • Diabetes Complications / metabolism*
  • Dietary Supplements*
  • Drinking
  • Eating
  • Energy Metabolism
  • GTP Cyclohydrolase / metabolism
  • Lipids / blood
  • Metabolic Syndrome / complications*
  • Metabolic Syndrome / drug therapy*
  • Metabolic Syndrome / metabolism
  • Myocardium / enzymology
  • Nitric Oxide / blood
  • Nitric Oxide Synthase / metabolism
  • Rats
  • Rats, Zucker
  • Water


  • Blood Glucose
  • Lipids
  • Water
  • Citrulline
  • Nitric Oxide
  • Arginine
  • Nitric Oxide Synthase
  • GTP Cyclohydrolase