Research published in the Journal of Agricultural and Food Chemistry found watermelon juice is an effective remedy for reducing the recovery heart rate and muscle soreness in athletes who were given 500 ml of watermelon juice (16.9 oz) containing 1.17 grams of the naturally occurring amino acid L-citrulline.
Additional research indicates watermelon may possess the following health benefits:
Boosting Your Antioxidant Levels: Watermelon is exceptionally rich in lycopene (hence its red color) and other carotenoids such as lutein and beta carotene.[2] A 2003 study published in the Journal of Nutrition found that regular watermelon juice consumption resulted in significant increases in blood plasma concentrations of lycopene and beta carotene.[3] Keep in mind that lycopene has been found to have over 40 potential health benefits, and beta carotene (especially in its natural, food-complexed form) equally plentiful health benefits, adding extra significance to this finding. Also, the watermelon-induced increase in plasma antioxidant levels may lend explanation to why an epidemiological study of the Chinese found greater watermelon intake to be associated with a lower risk of cancer.
Reducing Blood Pressure/Improving Arterial Health: A 2012 study published in the American Journal of Hypertension found that middle-aged obese subjects with prehypertension or stage 1 hypertension who were given 6 weeks of treatment with a watermelon extract containing 6 grams of L-citrulline and L-arginine daily, experienced reduced ankle blood pressure and altered carotid wave reflection, an indication of improved arterial function.[5] The inability of the blood vessels to dilate and function properly is known as endothelial dysfunction, and is likely the most well-known initiating step in the pathogenesis of atherosclerosis. If watermelon can ameliorate or reverse this process, it would certainly provide a breakthrough alternative to many of the drugs used for primary prevention, such as the cholesterol-lowering statin drug class, whose side effects, numbering in the hundreds, include heart muscle dysfunction and damage.