Durk Pearson & Sandy Shaw’s®
Life Extension NewsTM
Volume 15 No. 2 • March-April 2012

Summers in Washington, DC are usually awful. Before the invention of air conditioning, everyone who could, including Congress, headed for the exits in early June and didn’t return until the end of August. Unfortunately, technological progress has unforseen consequences, and thanks to our ability to cool our buildings, DC now legislates all summer long.
— Patrick J. Michaels, CATO Institute,
Regulation magazine Fall 2011
Measure what is measurable, make measurable what is not.
— Galileo Galilei

Watermelon Juice is a Rich Natural Source of Citrulline, Precursor of Arginine — Protects against Hyperglycemia, Hyperlipidemia

A new paper1 reports on the benefits of watermelon juice, noting that watermelon is one of the few foods naturally rich in the amino acid citrulline, with amounts varying from 0.7 to 3.6 mg/g of fresh weight.

In this study, diabetic rats were treated with drinking water containing 0.2% arginine and two different concentrations of watermelon juice (63% or 94.5%) and the results compared to that of an untreated diabetic control group and a diabetic group that was treated only with 0.2% arginine in their drinking water. The researchers found that, as compared to the control untreated diabetic rats, rats receiving drinking water supplemented with watermelon juice had enhanced arginine bioavailability and increased arginine serum concentration and also had significant hypoglycemia, hypolipidemic, anti-oxidative stress effects, with the best effect resulting from 94.5% watermelon juice. For example, HDL-C was 72.47 ± 0.45 in normal controls, 57.37 ± 4.87 in diabetic controls, 91.56 ± 2.10 in the 0.2% arginine treated group, 82.47 ± 4.10 in the 0.2% arginine and 63% watermelon juice treated group, 95.10 ± 4.92 in the 0.2% arginine and 94.5% watermelon juice group.

The authors note that 1 to 3 grams of oral citrulline increase plasma arginine concentrations by 50% in patients with sickle cell anemia. As we have reported before (for example, see the interview with us, “Putting More Power Into Your Life” in the April 2006 issue of Life Enhancement Magazine), citrulline is derived from arginine when nitric oxide synthase uses arginine to create nitric oxide, an important signaling molecule and vasodilator, but then citrulline is recycled back to arginine.2 We include citrulline in our higher level arginine, citrulline, choline, plus cofactors formulation specifically to increase arginine recycling. In another paper referred to by the authors, oral administration of watermelon pomace* juice increased the mass of brown adipose tissue (the type of fat that expends energy creating heat), reducing excess white fat mass and serum concentrations of risk factors for cardiovascular disease, as well as increasing nitric oxide enodthelial function in Zucker diabetic obese rats.3

* Watermelon pomace juice preparation was described in the paper given by reference #1: “Pomace was prepared from the water­melon using a rack and cloth hydraulic press. Immediately before use, the pomace was squeezed using a juice maker. The resulting juice was filtered through a fine screen to obtain fluid, which was then added to drinking water for rats [at 63 or 94.5%].”


  1. El-Razek and Sadeek. Dietary supplementation with watermelon (Citrullus ianatus) juice enhances arginine availability and modifies hyperglycemia, hyperlipidemia, and oxidative stress in diabetic rats. Aust J Basic Appl Sci 5(6):1284-95 (2011).
  2. Hecker et al. The metabolism of L-arginine and its significance for the biosynthesis of endothelium-derived relaxing factor: cultured endothelial cells recycle L-citrulline to L-arginine. Proc Natl Acad Sci USA 87:8612-6 (1990).
  3. Wu et al. Dietary supplementation with watermelon pomace juice enhances arginine availability and ameliorates the metabolic syndrome in Zucker diabetic fatty rats. J Nutr 137:2680-5 (2007).

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