There's not much to dislike about watermelon, aside from how much room these rounded behemoths can take up in your shopping cart. The sweet, pink-fleshed fruits are packed with potassium, magnesium and vitamin C, and a few slices sure hit the spot on a hot summer's day.

Two new studies published in the scientific journal Nutrients suggest even more reasons to love watermelon: regular consumption was linked to an overall healthier diet with a lower intake of added sugar, and drinking watermelon juice for two weeks was found to improve heart rate variability.

"This study provides further evidence of the positive impact fruit and especially watermelon can have on the diet quality of children and adults," researchers wrote after analyzing data from the National Health and Nutrition Examination Survey (NHANES) study.

Watermelon health benefits: What the research says

The first Nutrients article involved a scientific review evaluating 56,133 people from the NHANES study. In the review, consuming watermelon (and drinking pure watermelon juice) was analyzed in a dietary recall survey. In those who reported eating watermelon, the usual daily intake was 125 grams among children and 161 grams among adults. (One cup of diced fresh watermelon is about 152 grams.)

The review found those who reported eating watermelon tended to have better overall diet quality compared with those who did not eat the fruit, including "greater than 5% higher intake of dietary fiber, vitamin A, magnesium and potassium."

It also noted what they did not eat. Watermelon consumers had "more than 5% lower intake of added sugars and total saturated fatty acids as well as higher intake of lycopene and other carotenoids."

The health benefits of eating watermelon are similar to previous studies that have shown fruit contributes to better nutrition. But watermelon does have an edge. As opposed to many fruits, it has high levels of the potent antioxidants lycopene, beta-carotene, beta-cryptoxanthin, and lutein and zeaxanthin. These nutrients help support eye health, healthy blood pressure, heart health, protection against oxidative stress and more.

How watermelon helps your heart

A second study out of Louisiana State University further bolsters the reputation of this healthy fruit by identifying some sweet heart health benefits. Researchers conducted a randomized, double-blind, placebo-controlled crossover trial on 18 healthy young men and women to test the effect of daily watermelon juice on heart rate. Specifically, it looked at heart rate variability (HRV), or the variation in time between two consecutive heartbeats. In a healthy, relaxed adult, that variation is higher. Research has shown factors such as stress, or even glucose tolerance tests, can reduce heart rate variability.

With that in mind, the study participants were randomized to complete two weeks of watermelon juice (500 mL) or a placebo drink, then they completed an oral glucose tolerance test. The trial found the watermelon juice blocked the effect of the test on HRV, lessening the glucose-induced reduction in heartrate variability and preserving the heart's high-frequency power.

The LSU study authors suggest that watermelon's L-arginine and L-citrulline content may boost nitric oxide levels, and that may be responsible for its effect keeping heartrate variability higher.

This is important because heart rate variability (HRV) can indicate not only a stress response but also imbalances in the autonomic nervous system—which is a factor in the development of cardiometabolic disease. Low variation in consecutive beats (low HRV) has been linked to increased heart disease risk and mortality. Hyperglycemia, blood vessel dysfunction and increased inflammation have also been associated with reduced HRV. Observational studies have found that HRV and autonomic nervous system dysfunction are likely to lead to obesity and type 2 diabetes, as well.

Is watermelon a superfood?

While not often labeled a "superfood" (which doesn't really have a firm definition), watermelons do have a lot of nutrients that are important for health. A large serving (about 280 g) of watermelon contains:

• 84 calories
• 0 g cholesterol
• 0 g saturated fat
• 314 mg potassium (8% DV)
• 28 mg magnesium (7% DV)
• 23 mg vitamin C (37% DV)

This antioxidant-rich summer fruit also has vitamin A and lycopene, the amino acids L-arginine and citrulline, and the carotenoids lutein and zeaxanthin. Like vitamin C, vitamin A is important for immune system health. It also supports vision health, and it encourages the healthy function of your heart, lungs and other organs.

7 health benefits of watermelon

Although traditionally associated with summer, watermelon is available year-round in many parts of the country—and that's a good thing! In addition to its sweet taste, watermelon has a number of health benefits:

1. Provides cardiovascular, blood pressure and arterial health support.

   The amino acid L-arginine found in this fruit is crucial for nitric oxide (NO) synthesis, an important molecule for regulating vascular tone and lowering high blood pressure. Watermelon's citrulline is also converted to L-arginine, which magnifies watermelon's blood pressure health benefits.

2. Boosts hydration.

   The high water content of this fruit can help boost your water intake, which supports healthy skin, heart health and more.

3. Satisfies cravings.

   This sweet fruit makes for a low-fat, low-calorie snack that can help you stay on track for weight loss.

4. Promotes healthy nutrition.

   Eating watermelon can help you achieve healthy levels of vitamin C, magnesium and potassium in your diet.

5. Supports healthy digestion.

   The high water content and, to a lesser extent, fiber of this fruit helps keep things moving in the right direction.

6. Encourages post-workout recovery.

   This potassium-rich fruit makes a great post-exercise snack. Its amino acids and water content may help alleviate muscle soreness and encourage blood flow.

7. Supports immune system health.

   The vitamin A, vitamin C and lycopene in this healthy fruit all work to fight free radicals in your body, which promotes a strong immune system response and fights age-related damage at the cellular level.

Is it good to eat watermelon every day?

With its juicy sweetness and nutrient-dense profile, watermelon can be part of a heart-healthy and varied diet. The important key word here is "varied"—no one food can take care of all your dietary needs, even so-called superfoods.

Watermelon is a good source of vitamin C, lycopene and other nutrients, especially for people who don't really enjoy fruits like or vegetables, because it's so soft, sweet and palatable. Some kids will turn up their noses at lycopene-rich tomatoes, but almost every kid loves watermelon!

Can you eat the watermelon rind?

If you spent your childhood summers eating sliced watermelon and spitting out the watermelon seeds, this might surprise you—but, yes! The whole fruit is edible, including the green part. Despite what your parents might have said, you won't get sick eating the white part. Also, eating watermelon seeds won't cause a watermelon to grow in your stomach.

The watermelon rind actually contains the highest levels of citrulline and arginine and has a lot of fiber (much more than the flesh of the fruit).

There are several ways to enjoy the extra fiber and nutrition of watermelon rind:

• Toss it in a stir fry.

  Watermelon rind can be cut up like a vegetable and stir fried in a pan with broccoli and carrots. It also goes well in a curry or other saucy vegetable dish.

• Add to a smoothie.

  Blend white and green pieces of the watermelon rind with several pieces of fruit to create a juice, then freeze into cubes and add them to a smoothie for an antioxidant boost.

• Pickle it.

  The rind can be pickled and then used like other pickled veggies, such as tossed with pasta or a salad.

References

• Campos, Marcelo. "Heart Rate Variability: How It Might Indicate Well-being." Harvard Health Publishing. December 2021. https://www.health.harvard.edu/blog/heart-rate-variability-new-way-track-well-2017112212789
• Du, Xiaofen. et al. "Free Amino Acids and Volatile Aroma Compounds in Watermelon Rind, Flesh, and Three Rind-Flesh Juices." Pub Med. April 2022. https://pubmed.ncbi.nlm.nih.gov/35458735/
• Fulgoni, Kristen, et al. "Watermelon Intake Is Associated with Increased Nutrient Intake and Higher Diet Quality in Adults and Children." MDPI. November 2022. https://www.mdpi.com/2072-6643/14/22/4883
• Lennon, Annie. "Watermelons May Improve Diet Quality and Cardiometabolic Health." Medical News Today. May 2023. https://www.medicalnewstoday.com/articles/watermelons-may-improve-diet-quality-and-cardiometabolic-health
• Matthews, Rachel, et al. "The Effect of Watermelon Juice Supplementation on Heart Rate Variability and Metabolic Response during an Oral Glucose Challenge: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial." MDPI. February 2023. https://www.mdpi.com/2072-6643/15/4/810
• Naknaen, Phisut, et al. "Utilization of watermelon rind waste as a potential source of dietary fiber to improve health promoting properties and reduce glycemic index for cookie making." Pub Med. April 2016. https://pubmed.ncbi.nlm.nih.gov/30263285/
• Volino-Souza, Monica, et al. "Current Evidence of Watermelon (Citrullus lanatus) Ingestion on Vascular Health: A Food Science and Technology Perspective." Pub Med. July 2022. https://pubmed.ncbi.nlm.nih.gov/35889869/
• "Watermelon, raw." FoodData Central. April 2019. https://fdc.nal.usda.gov/fdc-app.html#/food-details/167765/nutrients
• "Vitamin A and Carotenoids." National Institutes of Health. August 2022. https://ods.od.nih.gov/factsheets/VitaminA-Consumer/

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The Life Extension Health News team delivers accurate information about vitamins, nutrition and aging. Our stories rely on multiple, authoritative sources and experts. We keep our content accurate and trustworthy, by submitting it to a medical reviewer.