Watermelon seeds are very high in protein, with 1 cup of dried seeds containing 30.6g, which is 61 percent of the daily recommended value. The protein in watermelon seeds consists of several amino acids, one of which is arginine. While the body produces some arginine, MedlinePlus states that some health conditions may benefit from additional arginine. Some of the health benefits of arginine include regulating blood pressure and treating coronary heart disease. Several other amino acids make up the protein in watermelon seeds, including tryptophan, glutamic acid, and lysine.