How healthy is watermelon?

According to the National Watermelon Promotion Board, you can consider watermelon either a fruit or a vegetable. The choice is yours! It looks like a fruit, tastes sweet like a fruit, and is similar to other melon types. However, it is actually a member of the Cucurbitaceae plant family of gourds, closely related to vegetables like pumpkins, squash, and cucumbers. It is planted, grown, and harvested in the same manner as other vegetables; therefore, many consider the watermelon to be a vegetable. Whether it is a fruit or vegetable is long debated; however, it packs a nutritional punch no matter in which category it lies.¹ 

The Nutritional Components of Watermelon

You may think that watermelon is just a lot of water, and therefore not really very nutrient-dense. Well, you are 50% right. Watermelon is 92% water, but water is essential to the body. Every part of your body needs water to function. You can take in all the water you need from both drinks and foods, making watermelon an excellent source of hydration.²

Despite being 92% water, watermelon is incredibly dense in nutrients. It is low in calories, low in fat, low in sodium, and contains nutrients such as:³

• Beta carotene and Vitamin A
• Vitamin C
• B vitamins such as folate, thiamin, niacin, and riboflavin
• Minerals such as potassium, calcium, magnesium, phosphorous, zinc, manganese, selenium, and fluoride
• Antioxidants such as lycopene, tryptophan, citrulline, lutein, zeaxanthin, leucine, lysine, arginine 
• Phytosterol (plant sterols)
• Choline

The combination of water and nutrients means that watermelon is thought to have several health benefits. 

What are the Health Benefits of Watermelon?

According to the Food and Drug Administration (FDA), watermelon only contains approximately 40 calories per cup (140g), making it low fat and healthy.⁴Some of the health benefits include:

It is hydrating

Containing 92% water and 0.6g of fiber (per cup), watermelon not only keeps your body hydrated but also helps you to feel full. It also provides you with electrolytes like potassium, regulating muscle contractions, maintaining fluid balance, helping with nerve signals, and keeping you hydrated. Two cups of watermelon is an excellent potassium source and will give you 6% of your daily recommended intake.⁴ Therefore, watermelon is a superb replenisher for the body.

Contains antioxidants

Antioxidants are a type of molecule that fight against free radicals in the body. Free radicals are known to damage your cells and cause health problems such as certain cancers, cardiovascular disease, inflammatory diseases, and aging. 

When there are too many free radicals in the body, it can lead to oxidative stress, which can damage your DNA and increase cancer risk.⁵

Watermelon contains antioxidants such as vitamin C, lycopene, tryptophan, citrulline, lutein, zeaxanthin, leucine, lysine, and arginine. The antioxidants lycopene and vitamin C are anti-inflammatories—one study was conducted in 2015 fed lab rats with watermelon powder. The results showed that they developed less oxidative stress and lower C-reactive protein levels (an inflammatory marker).⁶One serving of watermelon (two cups) provides 25% of your recommended daily intake of Vitamin C, making it an excellent source of this antioxidant.⁴It is thought that specific antioxidants like vitamin C might reduce the risk of asthma.⁸

Research has linked lycopene intake to a reduced risk of prostate cancer. ⁷Responsible for the red-color of watermelon flesh, lycopene has the highest antioxidant activity among all dietary antioxidants.¹⁰ Watermelon can be a particularly high lycopene source and is thought to help protect against conditions such as high cholesterol, diabetes, specific cancers (specifically digestive cancers), neurodegenerative diseases, and osteoporosis.³

Choline is another antioxidant present in watermelon that helps support brain and nervous system functions.⁹ In fact, one research paper discusses that watermelon could substantially contribute to the antioxidant levels of human diets and could be adopted in preventive medicine strategies.¹⁰

It may have a positive effect on heart health/blood pressure

Watermelon contains several nutrients that are beneficial for heart health, including:

• Magnesium – has been found to lower blood pressure in people who suffer from high blood pressure. ¹¹One portion (two cups of watermelon) contains 6% of your recommended daily value.¹² Research studies have identified that magnesium plays a vital role in cardiovascular health, and deficiencies may be linked to specific cardiovascular problems.¹³

• Potassium – the abundance and benefits of the potassium found in watermelon have already been touched on. However, potassium is also beneficial to heart health. The American Heart Association recommends that people with blood pressure above 120/80 (who do not have other health complications) naturally increase their potassium intake through diet. Potassium eases the tension in your blood vessel walls, which in turn helps lower blood pressure.¹⁴

• Vitamin B6 – research has identified that even a borderline deficiency of vitamin B6 is strongly associated with the risk of coronary artery disease.¹⁵ You are more prone to a B6 deficiency if you suffer from liver, kidney, digestive or autoimmune problems. People who are obese, heavy smokers, alcoholics, or pregnant women can be more likely to have a B6 deficiency. A portion of watermelon (two cups) contains 5% of your recommended daily amount of B6. It is a great way to boost your diet with a range of vitamins. 

• Citrulline – Watermelon is a rich source of citrulline. This is a type of amino acid that the body can metabolize into arginine, an essential amino acid. Arginine plays a critical role in cardiovascular and immune functions. It changes into nitric oxide that helps your blood vessels expand, lowering blood pressure. A research study showed that the plasma concentration of arginine was increased by taking citrulline in the form of watermelon juice.¹⁶

• Lycopene – the high levels of lycopene in watermelon have previously been noted, but their benefits also stretch to heart health. Lycopene has been found to help lower cholesterol and blood pressure. High consumption of lycopene has been found beneficial in preventing heart attacks, ischemic strokes, and atherosclerosis. Studies show that lycopene is readily available through the consumption of watermelon.³

• Phytosterols – some dietary guidelines recommend the intake of 2g of phytosterols per day to reduce low-density lipoprotein (LDL) cholesterol levels (bad cholesterol levels).¹⁷Studies have highlighted that consuming watermelon may be a beneficial way of increasing these nutrients through diet.¹⁸

It may help relieve muscle soreness

A 2017 study identified that watermelon juice with added citrulline improved recovery time and reduced muscle soreness in athletes post-exercise. Watermelon juice seems to enhance the absorption of citrulline. Supplementation with watermelon juice and citrulline could be beneficial to athletes. However, it isn’t clear if watermelon juice without added citrulline would have the same effect, and more studies are needed in this area.¹⁹

It might help improve metabolic syndrome

Metabolic syndrome is a cluster of conditions (increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels) that can increase your risk of heart disease, type 2 diabetes, and stroke. Research has shown the beneficial effects of consuming watermelon and watermelon supplementation on metabolic diseases.²⁰

A study carried out in 2019 investigated the effects of eating fresh watermelon on satiety, postprandial (post-meal) glucose and insulin response, and adiposity and body weight. After four weeks of eating two cups of watermelon per day, the study participants had higher levels of antioxidants in their blood, reduced BMI, lower body weight, improved waist-hip ratio, and lower systolic blood pressure.²⁰ 

It contains vitamins that are good for skin health

Skin can be damaged by air pollution, chemicals, and UV rays due to the free radicals they produce. Antioxidants help to protect your skin from damage by destroying those free radicals. 

Vitamin C has been found to promote healthy skin, produce collagen, and reduce age-related skin damage.²² It is also beneficial for fighting acne and hyperpigmentation.²¹

Watermelon is high in vitamin A, vitamin C, and antioxidants that are all known for their benefits to skin health. 

Are there any Risks or Side Effects to Eating Watermelon? Overall, watermelon is a healthy fruit to eat. However, some people may need to take precautions. 

• Allergies. If you have an allergic reaction to consuming watermelon, such as hives, rash, swelling, sickness, or difficulty breathing, then seek medical attention. Allergic reactions can be severe and, in some cases, trigger anaphylaxis. Watermelon allergies are rare. However, if you have a watermelon allergy, you will need to avoid the fruit, food, drinks, or consumables containing watermelon.
• Diabetes. Although a healthy food, watermelon does contain natural sugars. Therefore, it may affect glucose levels in someone with diabetes. Eating the whole fruit is generally the best way to consume watermelon, and fruit is fine to include in your diet. However, you may want to eat watermelon in moderation. If you have any concerns about your diet and blood glucose levels, then consult your diabetic care team for support and advice.

On the whole, there isn’t much of a downside to eating watermelon. You can easily include it in your diet by eating the fruit, blending into a juice or smoothie, roasting the seeds, or adding it to salad dishes. Yes, you can eat the seeds! In fact, you can eat the entire fruit, even the rind. The rind can be used in a stir fry or pickled, for example. 

Watermelons are both fruit and vegetable, full of hydration, and packed with vitamins, antioxidants, and minerals. Eat the fruit in its purest form to get the most benefit without any additives. Even if you have no interest in the health benefits, they are a pretty tasty snack to satisfy a sweet craving.

References:

1. National Watermelon Promotion Board. Facts & FAQs – Watermelon Board. https://www.watermelon.org/watermelon-101/facts-faqs/. Published 2021. Accessed January 25, 2021.

2. Plain Water, the Healthier Choice. Centers for Disease Control and Prevention. https://www.cdc.gov/nutrition/data-statistics/plain-water-the-healthier-choice.html. Published 2021. Accessed January 25, 2021.

3.Naz A, Butt MS, Sultan MT, Qayyum MM, Niaz RS. Watermelon lycopene and allied health claims. EXCLI J. 2014;13:650-660. Published 2014 Jun 3.

4. Watermelon.org. https://www.watermelon.org/wp-content/uploads/2020/01/FDAWatermelonLabel.pdf. Published 2021. Accessed January 25, 2021.

5. Liguori I, Russo G, Curcio F et al. Oxidative stress, aging, and diseases. Clin Interv Aging. 2018;Volume 13:757-772. doi:10.2147/cia.s158513

6. Hong M, Hartig N, Kaufman K, Hooshmand S, Figueroa A, Kern M. Watermelon consumption improves inflammation and antioxidant capacity in rats fed an atherogenic diet. Nutrition Research. 2015;35(3):251-258. doi:10.1016/j.nutres.2014.12.005

7. Chen P, Zhang W, Wang X et al. Lycopene and Risk of Prostate Cancer. Medicine (Baltimore). 2015;94(33):e1260. doi:10.1097/md.0000000000001260

8. Milan S, Hart A, Wilkinson M. Vitamin C for asthma and exercise-induced bronchoconstriction. Cochrane Database of Systematic Reviews. 2013. doi:10.1002/14651858.cd010391.pub2

9. Office of Dietary Supplements – Choline. Ods.od.nih.gov. https://ods.od.nih.gov/factsheets/Choline-HealthProfessional/. Published 2021. Accessed January 25, 2021.

10. Tlili I, Hdider C, Lenucci M, Riadh I, Jebari H, Dalessandro G. Bioactive compounds and antioxidant activities of different watermelon (Citrullus lanatus (Thunb.) Mansfeld) cultivars as affected by fruit sampling area. Journal of Food Composition and Analysis. 2011;24(3):307-314. doi:10.1016/j.jfca.2010.06.005

11. Kawano Y, Matsuoka H, Takishita S, Omae T. Effects of Magnesium Supplementation in Hypertensive Patients. Hypertension. 1998;32(2):260-265. doi:10.1161/01.hyp.32.2.260

12. Watermelon, raw. U.S. DEPARTMENT OF AGRICULTURE. https://fdc.nal.usda.gov/fdc-app.html#/food-details/167765/nutrients. Published 2019. Accessed January 26, 2021.

13. DiNicolantonio J, Liu J, O’Keefe J. Magnesium for the prevention and treatment of cardiovascular disease. Open Heart. 2018;5(2):e000775. doi:10.1136/openhrt-2018-000775

14. How Potassium Can Help Control High Blood Pressure. www.heart.org. https://www.heart.org/en/health-topics/high-blood-pressure/changes-you-can-make-to-manage-high-blood-pressure/how-potassium-can-help-control-high-blood-pressure#:~:text=Understanding%20the%20heart%2Dhealthy%20benefits%20of%20potassium&text=Potassium%20also%20helps%20to%20ease,80%20who%20are%20otherwise%20healthy. Published 2021. Accessed January 26, 2021.

15. Lin P, Cheng C, Liaw Y, Lee B, Lee T, Huang Y. Low pyridoxal 5′-phosphate is associated with increased risk of coronary artery disease. Nutrition. 2006;22(11-12):1146-1151. doi:10.1016/j.nut.2006.08.013

16. Collins J, Wu G, Perkins-Veazie P et al. Watermelon consumption increases plasma arginine concentrations in adults. Nutrition. 2007;23(3):261-266. doi:10.1016/j.nut.2007.01.005

17. Cabral C, Klein M. Phytosterols in the Treatment of Hypercholesterolemia and Prevention of Cardiovascular Diseases. Arq Bras Cardiol. 2017. doi:10.5935/abc.20170158

18. Abu-Hiamed H. Chemical Composition, Flavonoids and β-sitosterol Contents of Pulp and Rind of Watermelon (Citrullus lanatus) Fruit. Pakistan Journal of Nutrition. 2017;16(7):502-507. doi:10.3923/pjn.2017.502.507

19. Martínez-Sánchez A, Ramos-Campo D, Fernández-Lobato B, Rubio-Arias J, Alacid F, Aguayo E. Biochemical, physiological, and performance response of a functional watermelon juice enriched in L-citrulline during a half-marathon race. Food Nutr Res. 2017;61(1):1330098. doi:10.1080/16546628.2017.1330098

20. Lum T, Connolly M, Marx A et al. Effects of Fresh Watermelon Consumption on the Acute Satiety Response and Cardiometabolic Risk Factors in Overweight and Obese Adults. Nutrients. 2019;11(3):595. doi:10.3390/nu11030595

21. Wang K, Jiang H, Li W, Qiang M, Dong T, Li H. Role of Vitamin C in Skin Diseases. Front Physiol. 2018;9. doi:10.3389/fphys.2018.00819

22. Telang P. Vitamin C in dermatology. Indian Dermatol Online J. 2013;4(2):143. doi:10.4103/2229-5178.110593

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