Watermelon is native to Africa. It was a valuable and portable source of water for life in the desert and when natural water supplies were contaminated. Ancient hieroglyphics show that watermelons were cultivated in Egypt and India as far back as 2500 B.C..
Watermelon contains only 46 calories per cup, which is lower than low-sugar fruits like berries. It is high in vitamin C, vitamin A and many healthy plant compounds. One cup of watermelon has many other nutrients as well:
- Vitamin C: 21% of the Reference Daily Intake (RDI)
- Vitamin A: 18% of the RDI
- Potassium: 5% of the RDI
- Magnesium: 4% of the RDI
- Vitamins B1, B5 and B6: 3% of the RDI
Watermelon is also high in carotenoids, including beta-carotene and lycopene. Plus, it has citrulline, an important amino acid.
The citrulline may increase nitric oxide levels in the body. Nitric oxide helps your blood vessels expand, which lowers blood pressure.
Watermelon also contains antioxidants. Antioxidants help remove molecules known as free radicals, or reactive species, from the body. The body produces free radicals during natural processes like metabolism. They can also develop through smoking, air pollution, stress, and other environmental pressures. If too many free radicals stay in the body, oxidative stress will happen. This can result in cell damage and may lead to a range of diseases, such as cancer and heart disease. The body can remove some free radicals naturally, but dietary antioxidants support this process.
The vitamin C in watermelon helps the body to produce collagen. Collagen is essential for cell structure and immune function. Vitamin C also promotes wound healing. Studies suggest that vitamin C may help promote healthy skin, including reducing the risk of age-related damage.
In a 2012 study, researchers found that watermelon extract reduced blood pressure in and around the ankles of middle-aged people with obesity and early hypertension. L-citrulline and L-arginine are two of the antioxidants in watermelon and the authors suggest these may improve the function of the arteries.
Studies suggest that lycopene may help lower cholesterol and blood pressure. It can also help prevent oxidative damage. According to studies in obese, postmenopausal women and Finnish men, lycopene may also reduce the stiffness and thickness of artery walls.
Lycopene may also help protect against heart disease. A 2017 review suggested that it might do this by reducing inflammation linked with high-density lipoprotein (HDL) or “good” cholesterol.
Lycopene is found in several parts of the eye where it helps protect against oxidative damage and inflammation. It may also prevent age-related macular degeneration (AMD).
Some studies have also linked lycopene intake with a lower risk of prostate cancer.
Some people use diuretic drugs to help their body remove excess water and salt. A 2014 mouse study concluded that watermelon’s diuretic action might be as effective as that of furosemide, which is a well-known diuretic. This could make it a natural option for people with excess fluid, although never stop taking a prescription diuretic without talking to your healthcare provider.
How to Buy
Watermelon season runs from May to September, but its peak is mid-June to late August. Common types of watermelon include seedless, picnic, icebox, and yellow/orange-fleshed. Each type also has multiple varieties. Seedless watermelons won’t have dark black seeds but will have small white underdeveloped seeds that are fine to eat. Picnic watermelons are large, round or oblong, with green rind and red flesh. The icebox is like a personal-size watermelon, small and round and perfect for one person or a small family. The yellow/orange watermelons have yellow-orange flesh and can have seeds, but not always.
When buying a watermelon, look for one that is firm, heavy, and symmetrical without soft spots or bruising. Some experts believe that making sure the underside where it lies on the ground is a pale yellow color, not white or light green, is a sure sign of ripeness. But others use the “thumping method” with great success.
Flick your middle finger off your thumb and against the melon, listening for a deep, rich thud. This indicates that your melon is ripe.
How to Store
Watermelons are picked when they are ripe so they will not continue to ripen and soften much at room temperature; melons picked before their prime will never develop full flavor. A whole watermelon can be stored in the refrigerator for up to one week or at room temperature for a week or two. Cut watermelon should be placed with the cut against a plate, refrigerated and used within three to five days. You can also freeze cut watermelon, but the texture will be soft when thawed (which is fine for cold soups and smoothies).
How to Cook
Tips for serving watermelon include:
Juice: Place diced watermelon and a few ice cubes in a blender for a cold, refreshing, electrolyte drink.
Salad: Add watermelon and mint to a bed of spinach leaves. Drizzle with balsamic dressing.
Smoothies: Make a watermelon smoothie or combine with orange juice. Remember that juicing breaks down the fiber, making the sugar easier to absorb. People with diabetes should consider eating fresh, whole watermelon rather than drinking juice.
Roasted seeds: Roast the watermelon seeds in an oven for 15-20 minutes. One ounce of seeds can provide around 8 g of protein, or 14% – 17% of a person’s daily protein needs.