Watermelon: A Tasty Summer Treat That’s Good for Heart Health

Watermelon.

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Summertime means warm weather, and with increasing temperatures come backyard barbeques and potluck celebrations. No summer cookout is complete without the “essential” foods, and watermelon is a favorite for many of us. The juicy red fruit is tasty and refreshing and may even be good for our health.

Watermelon is a whopping 92 percent water. The extremely high water content makes snacking on the melon a fantastic way to keep hydrated in the hot summer sun or replenish fluids after a sweaty workout. But watermelon is more than just water; it’s also a source of vitamin C, vitamin A, potassium, magnesium, B vitamins, and nutrients that contain red and yellow pigments (called carotenoids).

Watermelon also contains an amino acid called L-citrulline—sometimes referred to as just citrulline— which plays an important role in maintaining heart health. Our bodies turn citrulline into another amino acid called L-arginine. We need L-arginine to make nitric oxide, a substance that helps regulate our blood pressure, and endothelial function, the ability of our blood vessels to relax to keep our blood flowing. Low levels of L-arginine increase our risk for cardiovascular diseases such as hypertension, buildup of plaque in the arteries (atherosclerosis) and heart failure. Not having enough nitric oxide has been found to be a cause of endothelial dysfunction. A study in American Journal of Physiology—Endocrinology and Metabolism has shown that citrulline supplements increase nitric oxide levels in adults with heart failure.

Citrulline might also be good for athletes. Research published in the Journal of Applied Physiology looked at the effects of citrulline supplementation on exercise capacity in healthy young men. Results showed that citrulline was able to increase the amount of high-intensity exercise and sprint work these men could do. In the same study, citrulline lowered the men’s blood pressure.

The question remains of how much watermelon you would need to eat to get the full benefits of citrulline. One cup of watermelon contains about 200–300 milligrams of citrulline. Based on the typical dose given in many research studies, you would have to eat 15 cups of the fruit—a bit much for most people to stomach. However, every little bit counts, so slice up some watermelon today. Your taste buds—and your blood vessels—will thank you for it.

Brady HolmerBrady Holmer is a PhD student in exercise physiology at the University of Florida. His lab focuses on cardiovascular physiology; mainly how exercise can play a role in health, disease and aging. 

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