The Truth About Watermelons

Larry A. Law

Watermelon season will soon be coming again this summer. While watermelons are mostly water (90%), they are also full of a surprising amount of nutrition. Can something so sweet and tasty be good for us? Watermelon is high in natural sugars, but because they contain so much water, they are actually low on the glycemic index and don't spike blood sugar when you eat them. Watermelon is loaded with vitamins A, B6, and C, lycopene, antioxidants and minerals. Just one cup of watermelon has 1.5 times the lycopene of a fresh, large tomato. And who can eat just one cup of watermelon? Lycopene is a powerful anti-inflammatory and antioxidant that plays a vital role in protecting the cardiovascular system, supporting bone health, and preventing cancer. Watermelons are probably the highest source of lycopene from natural foods. Another powerful phytochemical is citrulline—an animo acid that gets converted into L-arginine in the body. L-arginine is used to create nitric oxide (NO) which benefits the heart and blood vessels. NO causes blood vessels to relax and open up. This lowers blood pressure, helping to get more oxygen to the cells. 

Types of Watermelon

There are three types of watermelon commonly enjoyed in the United States:

1) Icebox watermelons are smaller, weighing 5-15 pounds

2) Picnic watermelons weigh between 15-50 pounds and probably need to be cut in half before storing in your fridge

3) Seedless watermelons are similar to picnic watermelons and came on the scene about 50 years ago. While they don't contain mature, black seeds (also full of nutrition), they sometimes contain immature white seeds. There has been a misconception that seedless watermelons came about via genetic engineering, but that is not true. GMO did not get rolling until the 1990s. These watermelons are actually a sterile hybrid created by cross-pollinating male pollen for watermelon with a female watermelon flower. In a sense, seedless watermelons are like the mule of watermelons. A mule is the offspring of a male donkey (a jack) and a female horse (a mare). A horse has 64 chromosomes, and a donkey has 62. The mule ends up with 63. Mules can be either male or female, but because of the odd number of chromosomes, they can't reproduce. With seedless watermelons, the fruit cannot form unless the flowers are pollinated, and the seedless plants cannot make pollen. You have to grow some normal watermelons nearby to provide that. The pollen will not fertilize the seeds in the usual way, of course, but it stimulates the seedless flowers to form a fruit.

It's Not Just the Red Part

While most of us enjoy eating the juicy red part of the watermelon, the whole thing is actually full of nutrition—even the green rind. The rind is full of chlorophyll and contains more citrulline than the red part. You can actually throw your rinds into a blender with some freshly-squeezed lime juice and make a slushy nutritious treat. And don't spit out those black seeds unless you are in a seed-spitting contest. They are full of iron, zinc, fiber, and protein. On the farm, we fed our rinds to the animals and they loved it—they have a nose for nutritious good eats. 

How to Pick a Watermelon

This is an age old question. Look at the underside of the watermelon for a pale, butter-colored yellow spot—not white or green. This is one of the best indicators of watermelon ripeness. Then, pick up a few and choose the heaviest for its size. People also 'thump' the watermelon to check for a hollow, bass sound.