Watermelon is believed to have to have originated from the Kalahari Desert in Southern Africa. Watermelons were first cultivated in Egypt, and hieroglyphics depicting watermelons have been found in tombs. Today China is the world’s biggest producer of watermelons, with Russia, Turkey, Iran and the United States being the other big cultivators. Japanese farmers invented the idea of forcing their watermelons to grow into a square shape by inserting them into glass boxes while still growing.

Watermelon is a rich source of citrulline, an amino acid that can be metabolized to arginine, an essential amino acid. In a controlled human study, it was demonstrated that plasma concentration of arginine is increased from the citrulline in watermelon.

Arginine is used in the synthesis of nitric oxide, a vasodilator, meaning that it increases blood flow to all areas of the body. The effect it has on blood flow also makes watermelon a good choice for athletes and bodybuilders to juice up on. Nitric oxide also plays an essential role in cardiovascular and immune functions.

Watermelon is rich in the antioxidant lycopene, which is a carotenoid that gives watermelon and certain other fruits and vegetables their color. In another human study, it was suggested that and fruits such as watermelon rich in lycopene and other carotenoids might be protective against prostate cancer.

Arginine plays an important part in the healing of wounds and the removal of ammonia from the body. Excess ammonia in the blood can lead to fatigue, kidney and liver disease.

Watermelon has a low calorie content, and with it's high nutrient and water content, it's an ideal choice of fruit to incorparate into a weight loss program.