While watermelons are an excellent source of vitamin C, what makes them a standout among fruits is their lycopene—a red pigment and an antioxidant, most famously found in tomatoes, closely related to beta-carotene. Gram for gram, red-fleshed watermelons actually provide more lycopene than tomatoes, and the lycopene in watermelons, unlike the lycopene in tomatoes, can be used by the body without any processing. Lycopene has attracted the interest of researchers due to its apparent importance in heart health. Here's a few things researchers have discovered about lycopene and heart health:
In some research, a high dietary intake of lycopene has been associated with a lower risk of heart attack and heart failure.
Low blood levels of lycopene have been linked to increased risks of high blood pressure, stroke, heart attack, and death from any cause.
So, when watermelon season comes around, there's good reason to choose watermelons with flesh that is the deepest red—they have more lycopene than the yellow and orange varieties.
Source: Diabetes Care