The watermelon (Citrullus lanatus) is a large, sweet fruit from southern Africa. It’s related to cantaloupe, zucchini, pumpkin, and cucumber.
Watermelon is packed with water and nutrients, contains very few calories, and is exceptionally refreshing.
Moreover, it’s a good dietary source of citrulline and lycopene, two powerful plant compounds.
This juicy melon may have several health benefits, including lower blood pressure, improved insulin sensitivity, and reduced muscle soreness.
While watermelons are predominantly eaten fresh, they can also be frozen, made into juice, or added to smoothies.
This article tells you everything you need to know about watermelon.
Watermelon nutrition facts
Watermelon consists mostly of water (91%) and carbs (7.5%). It provides almost no protein or fat and is very low in calories.
The nutrients in 2/3 cup (100 grams) of raw watermelon are:
- Calories: 30
- Water: 91%
- Protein: 0.6 grams
- Carbs: 7.6 grams
- Sugar: 6.2 grams
- Fiber: 0.4 grams
- Fat: 0.2 grams
Watermelon contains 12 grams of carbs per cup (152 grams).
The carbs are mostly simple sugars, such as glucose, fructose, and sucrose. Watermelon also provides a small amount of fiber.
Watermelons’ glycemic index — a measure of how quickly foods raise blood sugar levels after meals — ranges from 72–80, which is high.
However, each serving of watermelon is relatively low in carbs, so eating it should not majorly affect blood sugar levels.
Watermelon is a poor source of fiber, providing only 0.4 grams per 2/3 cup (100 grams).
However, its fructose content is considered high in FODMAPs, or fermentable short-chain carbohydrates.
Eating high amounts of fructose can cause unpleasant digestive symptoms in individuals who cannot fully digest them, such as those with fructose malabsorption.
Summary: Watermelon is low in calories and fiber and consists mostly of water and simple sugars. It also contains FODMAPs, which cause digestive problems in some people.
Vitamins and minerals of watermelons
Watermelon is a good source of vitamin C and a decent source of several other vitamins and minerals.
- Vitamin C. This antioxidant is essential for skin health and immune function.
- Potassium. This mineral is important for blood pressure control and heart health.
- Copper. This mineral is most abundant in plant foods and often lacking in the Western diet.
- Vitamin B5. Also known as pantothenic acid, this vitamin is found in almost all foods to some extent.
- Vitamin A. Watermelon contains beta carotene, which your body can turn into vitamin A.
Summary: Watermelon is a good source of vitamin C and contains decent amounts of potassium, copper, vitamin B5, and vitamin A (from beta carotene).
Other plant compounds
Watermelon is a poor source of antioxidants compared to other fruits.
However, it’s rich in the amino acid citrulline and the antioxidant lycopene, which have numerous benefits for health.
Watermelon is the richest known dietary source of the amino acid citrulline. The highest amount is found in the white rind that surrounds the flesh.
In your body, citrulline is transformed into the essential amino acid arginine.
Both citrulline and arginine play an important role in synthesizing nitric oxide, which helps lower blood pressure by dilating and relaxing your blood vessels.
Arginine is also important for many organs — such as your lungs, kidneys, liver, and immune and reproductive systems — and has been shown to facilitate wound healing.
Studies note that watermelon juice is a good source of citrulline and can considerably increase blood levels of both citrulline and arginine.
Suggested read: 9 proven health benefits of watermelon
Though watermelon is one of the best dietary sources of citrulline, you would have to consume about 15 cups (2.3 kg) at once to meet the recommended daily intake for arginine.
Watermelon is the best-known fresh source of lycopene, a powerful antioxidant responsible for its red color.
Fresh watermelon is a better source of lycopene than tomatoes.
Human studies show that fresh watermelon juice effectively raises blood levels of both lycopene and beta-carotene.
Your body uses lycopene to some extent to form beta-carotene, which is then converted into vitamin A.
Summary: Watermelon is a good source of the amino acid citrulline and the antioxidant lycopene, which play important roles in your body.
Health benefits of watermelons
Watermelons and their juice are linked to several health benefits.
Lower blood pressure
High blood pressure is a major risk factor for chronic disease and premature death.
Watermelon is a good source of citrulline, which is converted into arginine in your body. Both of these amino acids aid nitric oxide production.
Nitric oxide is a gas molecule that causes the tiny muscles around your blood vessels to relax and dilate. This leads to a reduction in blood pressure.
Supplementing with watermelon or its juice may reduce blood pressure and arterial stiffness in people with high blood pressure.
Reduced insulin resistance
Insulin is a vital hormone in your body that controls blood sugar.
Insulin resistance is the condition in which your cells become resistant to the effects of insulin. This can lead to elevated blood sugar levels and is linked to metabolic syndrome and type 2 diabetes.
In some studies, watermelon juice and arginine intake are associated with reduced insulin resistance.
Reduced muscle soreness after exercise
Muscle soreness is a well-known side effect of strenuous exercise.
One study showed that watermelon juice effectively decreases muscle soreness following exercise.
Research on watermelon juice (or citrulline) and exercise performance gives mixed results. One study found no effect, while another observed improved performance in untrained — but not well-trained — individuals.
Summary: Watermelon may reduce some people’s blood pressure and insulin resistance. It is also linked to reduced muscle soreness after exercise.
Adverse effects of watermelons
Most people tolerate watermelon well.
However, it may cause allergic reactions or digestive problems in some individuals.
Allergy to watermelon is rare and usually associated with oral allergy syndrome in individuals sensitive to pollen.
Symptoms include itchy mouth and throat and swelling of the lips, mouth, tongue, throat, and/or ears.
Watermelon contains relatively high amounts of fructose, a type of FODMAP that some people do not fully digest.
FODMAPs like fructose may cause unpleasant digestive symptoms, such as bloating, gas, stomach cramps, diarrhea, and constipation.
Individuals sensitive to FODMAPs, such as those with irritable bowel syndrome (IBS), should avoid watermelons.
Summary: Allergy to watermelons is rare but does exist. This fruit also contains FODMAPs, which may cause unpleasant digestive symptoms.
Watermelon is an exceptionally healthy fruit.
It’s loaded with citrulline and lycopene, two powerful plant compounds linked to lower blood pressure, improved metabolic health and decreased muscle soreness after exercise.
Moreover, it’s sweet, delicious, and packed with water, making it excellent for maintaining hydration.
For most people, watermelon is a perfect addition to a healthy diet.