A watermelon contains about 6% sugar and 91% water by weight. As with many other fruits, it is a source of vitamin C.
The amino-acid citrulline was first extracted from watermelon and analyzed.[10] Watermelons contain a significant amount of citrulline and after consumption of several kilograms, an elevated concentration is measured in the blood plasma; this could be mistaken for citrullinaemia or other urea cycle disorders.[11]
Watermelon rinds are also edible, but most people avoid eating them due to their unappealing flavor. They are used for making pickles,[12] and sometimes used as a vegetable.[13][better source needed] In China, they are stir-fried, stewed or more often pickled.[citation needed] Pickled watermelon rind is sometimes eaten in the Southern US.[14][better source needed] Watermelon juice can be made into wine.[15][better source needed]
Watermelon is mildly diuretic[16] and contains large amounts of carotenoids.[17] Watermelon with red flesh is a significant source of lycopene. Preliminary research indicates the consumption of watermelon may have antihypertensive effects.