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Watermelon is a sweet and refreshing low calorie summer snack. It provides hydration and also essential nutrients, including vitamins, minerals, and antioxidants.

Along with cantaloupe, honeydew, and cucumber, watermelons are a member of the Cucurbitaceae family.

There are five common types of watermelon: seeded, seedless, mini, yellow, and orange.

In this article, learn more about the possible health benefits and nutritional content of watermelon, some tips for serving it, and who should limit it.

a juicy looking watermelonShare on Pinterest
The water content of watermelon can help a person stay hydrated.

Watermelon is around 90% water, which makes it useful for staying hydrated in the summer. It can also satisfy a sweet tooth with its natural sugars.

Watermelon also contains antioxidants. These substances can help remove molecules known as free radicals, or reactive species, from the body. The body produces free radicals during natural processes, such as 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 can occur. 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.

Below are some of the ways antioxidants and other nutrients in watermelon may help protect a person’s health.

What other foods provide antioxidants? Click here to find out.

Asthma prevention

Some experts believe that free radicals contribute to the development of asthma. The presence of certain antioxidants in the lungs, including vitamin C, may reduce the risk of having asthma.

Studies have not confirmed that taking vitamin C supplements can help prevent asthma, but a diet that is rich in vitamin C may offer some protection.

A cup of watermelon balls weighing around 154 grams (g) provides 12.5 milligrams (mg) of vitamin C, or between 14% and 16% of a person’s daily needs.

What types of exercise can people do if they have asthma? Find out here.

Blood pressure

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. The authors suggested that L-citrulline and L-arginine — two of the antioxidants in watermelon — may improve the function of the arteries.

Lycopene — another antioxidant in watermelon — may 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.

Phytosterols are plant compounds that may help manage low-density lipoprotein (LDL) or “bad” cholesterol. Some guidelines recommend consuming 2 grams (g) of phytosterols each day. 154 g of watermelon balls provides a small amount, at 3.08 mg.

Reducing LDL cholesterol may help prevent high blood pressure and cardiovascular disease (CVD), but the precise impact of phytosterols on CVD remains unclear.

Which foods can help lower blood pressure? Find out here.

Cancer

The National Cancer Institute (NCI) note that free radicals can play a role in the development of some types of cancer. The oxidative stress they cause can result in DNA cell damage.

Dietary antioxidants in watermelon, such as vitamin C, may help prevent cancer by combatting free radicals.

Some studies have also linked lycopene intake with a lower risk of prostate cancer.

Click here to learn more about the links between cancer and diet.

Digestion and regularity

Watermelon has high water content and also provides some fiber. These nutrients help promote a healthy gut by preventing constipation and promoting regularity of bowel movements.

Hydration

Watermelon is around 90% water and also provides electrolytes, such as potassium. This makes it a healthful choice of snack during the hot summer months.

People can eat watermelon fresh, as juice, or frozen in slices for a tasty cold Popsicle-style snack.

Water is essential for health. Learn more here about why we need it.

Brain and nervous system

Choline is another antioxidant that occurs in watermelon.

It contributes to the following functions and activities:

  • muscle movement
  • learning and memory
  • maintaining the structure of cell membranes
  • the transmission of nerve impulses
  • early brain development

One theory suggests that choline may help slow the progression of dementia in Alzheimer’s disease, but there is not enough evidence to confirm this.

What is a brain-boosting diet? Find out here.

Muscle soreness

Watermelon and watermelon juice may reduce muscle soreness and improve recovery time following exercise in athletes.

In a 2017 study, athletes drank either half a liter of either a placebo or watermelon juice with added L-citrulline, 2 hours before running a half marathon race. Those who consumed the watermelon drink reported less muscle soreness 24–72 hours after the race.

It is unclear whether consuming watermelon juice without added L-citrulline would have the same effect.

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Skin

Watermelon contains vitamin C, which the body needs 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.

Discover some tips on other skin-friendly foods.

Metabolic syndrome

In 2019, researchers published findings indicating that watermelon may improve features of metabolic syndrome, including obesity and cardiovascular measures. In the study, 33 people with overweight or obesity consumed either 2 cups of watermelon or low-fat cookies each day for 4 weeks.

The people who ate watermelon reported feeling less hungry and more satisfied for longer than those who ate the cookies.

In addition, after 4 weeks, those who ate watermelon had:

  • higher levels of antioxidants in their blood
  • lower body weight and body mass index (BMI)
  • lower systolic blood pressure
  • improved waist-to-hip ratio

Those who ate the cookies had higher levels of oxidative stress than the watermelon group. Their blood pressure and body fat also increased.

The results suggest that watermelon may be a good choice of snack for people with obesity and metabolic syndrome.

Can people with diabetes eat watermelon? Find out here.

Diuretic properties

Some people use diuretic drugs to help their body remove excess water and salt. This can be useful for people with kidney problems, high blood pressure, and other conditions.

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. Never stop taking a prescription diuretic without talking to your healthcare provider.

What other natural diuretics are there? Find out here.

The table below shows the amount of each nutrient in a cup of melon balls weighing around 154 g.

It also shows how much an adult needs of each nutrient, according to the 2015–2020 Dietary Guidelines for Americans. Requirements vary according to the individual’s sex and age.

NutrientAmount in 1 cup watermelon Daily adult requirement
Energy (calories)46.21,800 – 3,000
Carbohydrate (g)11.6, including 9.6 g of sugar130
Fiber (g)0.622.4 – 33.6
Calcium (millgrams [mg])10.81,000 – 1,200
Phosphorus (mg)16.9700
Magnesium (mg)15.4320 – 420
Potassium (mg)1724,700
Vitamin C (mg)12.575 – 90
Folate (mcg, DFE)4.6400
Choline (mg)6.3425 – 550
Vitamin A, RAE (mcg)43.1700 – 900
Beta carotene (mcg)467No data
Lutein & zeaxanthin (mcg)12.3 mcgNo data
Lycopene (mcg)6,980No data
Phytosterols (mg)3.08No data

Watermelon also contains some:

– B vitamins, such as thiamin, niacin, and riboflavin

– zinc, manganese, selenium, fluoride, and other essential minerals

– tryptophan, leucine, lysine, arginine, and other antioxidants

When buying a watermelon, people should look for one that is firm, heavy, and symmetrical without soft spots or bruising.

Tapping the outside can give a clue as to the texture of the fruit inside. Listen for a light and almost hollow sounding thud. This indicates the water and fruit contained is intact and has a stable structure.

Serving tips

Tips for serving watermelon include:

Juice: Place diced watermelon and a few ice cubes in a blender for a cold, refreshing, electrolyte drink that is perfect for rehydrating after exercise or a day in the sun.

Salad: Add watermelon, mint, and fresh mozzarella to a bed of spinach leaves for a tasty and healthful salad. Drizzle with balsamic dressing.

Smoothies: Make a watermelon smoothie or combine with orange juice for extra tang. 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 to make a tasty snack. One ounce (28.5 g) of seeds can provide around 8 g of protein, or 14% – 17% of a person’s daily protein needs.

A range of watermelon products is available for purchase online.

People should check the packaging of premade juices and candies, as these may have added sugar and may not be as healthful. Eating watermelon whole is the most healthful option.

Cantaloupe is another popular type of melon. Find out more.

Moderate amounts of watermelon present no serious health risk for most people, but some may need to take care.

Diabetes: Watermelon is a fruit with natural sugar content. People with diabetes must account for these carbs in their daily meal plan. It is better to consume watermelon whole rather than as a juice, as juicing removes the fiber, making the sugar easier for the body to absorb. This may increase the risk of a glucose spike. Remember to watch portion sizes as with all fruit and juices.

Allergy: Some may develop symptoms of an allergic reaction, such as hives, swelling, and difficulty breathing after eating watermelon. If this happens, the person needs medical attention, as it can sometimes lead to anaphylaxis, which is a life-threatening condition.

Learn more here about watermelon allergy.

Q:

My friend eats watermelon to get rid of water in her body, as she says this is good for losing weight? Is this correct?

A:

Watermelon may act as a natural diuretic, but this is not going to cause a loss of body fat. If your friend is replacing cookies, candy, or chips with watermelon as a snack, then she may indeed see some weight loss due to the reduction in added sugars and fats present in the cookies, etc.

Kathy W. Warwick, R.D., CDE Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.