Which compound in watermelon is associated with blood vessel dilation?

Citrulline is the compound in watermelon that is primarily associated with blood vessel dilation. This amino acid is known for its role in the synthesis of nitric oxide, a molecule that helps relax and widen blood vessels, thereby improving blood flow and reducing blood pressure. When citrulline is ingested, it is converted into arginine in the kidneys. While arginine also contributes to nitric oxide production, it is the direct content of citrulline in watermelon that has garnered significant attention for this effect, making it particularly noteworthy in discussions about cardiovascular health and exercise performance.

In contrast, arginine is another amino acid that plays a role in nitric oxide production but is not the specific compound highlighted in the context of watermelon. Quercetin is a flavonoid found in various fruits and vegetables with antioxidant properties, but it does not have a direct influence on blood vessel dilation. Lycopene, known for its antioxidant effects, is a carotenoid found in watermelon and has various health benefits, including potential cardiovascular benefits, but its primary mechanism does not directly involve dilation of blood vessels. Thus, the identification of citrulline as the key compound is well-supported by research on its physiological effects.