Nutrition

Watermelon Health Benefits and Nutrition Facts

✅ Evidence Based Article

The hot days in summer are never complete without watermelon. These healthy fruits are a favorite because they are sweet, fleshy, watery, and refreshing.

Moreover, each juicy bite of a watermelon is soaked with significant levels of vitamins, antioxidants, minerals and a modest amount of amino acids.

Read on to find out the nutrition facts and health benefits of this amazing fruit.

First, here are some watermelon facts and a brief history

The official name of watermelon is Citrullus Lanatus from the botanical family of Cucurbitaceae.

Melons are closely related to cucumbers, pumpkins, and squash. There are about 200 to 300 varieties, though there are only about 50 of them that are popular. (1)

All these varieties share the distinct mouth-watering sugary flesh encased in a solid rind characteristic. However, some watermelon types have higher sugar content while others have different colored rinds and pulp.

The varieties are primarily classified into four groups- seedless, picnic, yellow/orange and icebox types. (2)

The seedless watermelons were created in the 90s, and they have tiny underdeveloped seeds that can easily be consumed. They mature in 85 days and are usually 10 to 20 pounds. The picnic watermelons are larger, weigh about 16 to 45 pounds and have the traditional round shape, green rind, and red flesh.

The icebox type is smaller (5 to 15 pounds), can either have sweet pulp with dark green skin or golden once mature. Lastly are the yellow/orange type that can either be seeded or seedless. The flesh is either yellow or orange due to their higher content in beta-carotene and lycopene. (3)

Watermelons are thought to have originated from the Kalahari Desert in Africa. (4) The earliest recorded watermelon harvest occurred in Egypt, more than 4,000 years ago.

In Egypt, watermelons also have a cultural significance as they were often placed in the tombs of their kings, to nourish them in their afterlife. Up to date, these fruits are depicted on the walls of their ancient buildings.

By the 10th century, watermelons spread through the Mediterranean Sea to China, which is the current leading producer globally. (5) Later in the 13th century, watermelons found their way to Europe and the rest of the world.

Edible parts of a watermelon

The most common usage for watermelon is to slice or cut the red part into cubes for a quick cold snack or dessert.

However, what most people do not know is that all parts of a watermelon (both the red and white flesh) are good, just like its cousin the cucumber.

In fact, the white section nearest the rind that most people throw away contains more amino acids (specifically citrulline) than the red part. (6)

The rinds are sometimes eaten as a vegetable, and in China, they stir-fry, stew, or even pickle them. They have a beautiful subtle flavor like summer squash.

A hard watermelon drink can also be made using the rind. It is made by forming a hole in the melon then liquor is put inside and allowed to stay there for some time. The alcohol permeates into the flesh then its cut and served as intoxicating slices.

Recently, the nutrition expert community found out that watermelon seeds are impressively nutritious, especially when sprouted and shelled. The seeds can be eaten when dried and roasted or ground into flour.

They are high in vitamin Bs, proteins, magnesium, zinc and healthy fats. The special thing about watermelon seeds is the amount of fat that they contain.

One cup has approximately 51g of fats, 11g being saturated fats while the rest are heart-healthy fats (monounsaturated fats, polyunsaturated fats, and omega-6 fatty acids). (7)

Related:   18 Amazing Health Benefits of Mango

Watermelon’s Nutritional Profile

A single serving of watermelon is an excellent source of Vitamins A, C, and Bs, potassium, and calcium.

A significant portion of the calories come from its sugars, which is not a bad thing since they are natural sugars and not ultra-processed sugars.

There is also a substantial level of amino acids, but watermelon is not a complete protein source. Therefore, there is need to incorporate complementary protein sources to yield the required daily nutritional requirements.

Here is a summary of the nutritional values of watermelon nutrients (8)

Serving: I cup diced

Calories 46.2

Nutrient Amount % Daily Value
Total carbohydrate

Dietary fiber

Sugars

11.6g

0.6g

9.5g

4%

2%

Protein 0.9g 2%
Total Fats 0.23g 0%
Potassium 173mg 5%
Vitamin A 876IU 18%
Vitamin C 12.5mg 21%
Vitamin B3 0.3mg 1%
Vitamin B5 0.3mg 3%
Vitamin B6 0.1mg 3%
Calcium 10.8mg 1%
Iron 0.36mg 4%
Magnesium 15.4mg 4%
Water 141g  

 

Health benefits of watermelon

1.Cardiovascular health

Several nutrients in watermelon have unique benefits for the heart and the cardiovascular system in general.

First, watermelons have 9 to 13mg of lycopene, about 40% more than raw tomatoes. (9) Lycopene is the red pigment that gives watermelon and tomatoes their color. It acts as a potent antioxidant that protects against free radicals and oxidative damage. (10)

The high antioxidant activity has cardioprotective benefits in that it suppresses oxidation of low-density lipoproteins (LDL). (11) LDL cholesterol is considered to be the “bad cholesterol” that contributes to building up of fats in the arteries, a condition known as atherosclerosis.

This condition narrows the blood vessels, increasing the risk for heart attacks, stroke, and peripheral heart diseases. (12)

The citrulline present mostly in watermelon rinds is an amino acid that is turned into arginine in the kidneys. (13) Arginine improves blood flow by creating nitric oxide, a gas that helps to dilate the blood vessels.

It thus contributes to moderation of blood pressure by promoting vasodilation and enhancing blood flow. (14)

Watermelons also contain beta-carotene, which work in the same way as lycopene to lower cholesterol-induced oxidative damage on the cardiovascular system. (15) Note that lycopene levels in watermelon are best when the fruit is fully ripened. Also, when white, there is almost zero level of beta-carotene.

2.Keeps the body hydrated

Each bite of watermelon instantly explains how this fruit got its name. A single serving of watermelon has more than 90% of water content. (16)

Furthermore, where it originated in the Kalahari Desert, it was a valuable portable source of water, when water sources were contaminated.

For proper body hydration, one needs to replace water that is lost from the body with one that is almost similar to the body’s composition.

Watermelons consist of minerals and sugars that are close to this composition, and can therefore, rehydrate better than water alone. (17)

Staying hydrated makes up the base for body fluids including blood, sweat, and urine. It maintains blood pressure, ensuring that tissues are nourished with nutrients, get adequate oxygen supply, and that waste products are flushed out.

Optimal hydration also maximizes physical performance and brain function. A drop in fluid body volume means that there is no proper control of body temperature and there is no adequate blood flow to the muscles and brain.

The larger rise in body core temperature leads to glycogen breakdown in the tissues, which contributes to the early onset of fatigue. The result is headaches accompanied by sluggish performance.

For this reason, people in the athletic world note a significant drop in their output when not their bodies are not normally hydrated. (18)

3.Improves digestion

Watermelon contain a small amount of fiber and as mentioned before, plenty of water. Although water is taken for granted at times, it is one of the essential nutrients that the digestive system needs.

The body needs adequate water for production of saliva, digestive juices and for the provision of a fluid balance that helps transport nutrients throughout the body. Water also acts as a digestive aid that aids in digestion and absorbption of minerals. (19)

Water is also necessary for the digestion of soluble fiber, which promotes easy movement of material through the gastrointestinal tract and increases stool bulk. (20)

That is why dehydration is a common cause of poor digestion and constipation. Furthermore, watermelon is also a source of this defecation-friendly fiber.

4.Lowers inflammation and oxidative stress

Watermelons are high in beta-cryptoxanthin, Vitamin C and other antioxidants that protect the body from chronic inflammation. (21)

Inflammation is part of the body’s immune response that protects it from harmful stimuli and begins the healing process after an injury.

It is thus a critical process, but when prolonged, it causes a series of destructive reactions that cause damage to cells, ultimately leading to chronic diseases such as diabetes type 2.

Since inflammation is the key driver of most chronic diseases, watermelons help lower the risk of long-term diseases by suppressing inflammatory responses.

The anti-inflammatory substances present act by reducing the activity of pain and inflammation-causing enzymes such as cyclooxygenase. (22) This is the same way that non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen work.

The antioxidants present in watermelon also delay or prevent oxidative stress and the pathways that relate to many chronic illnesses such as cancer. (23)

They safely react with free radicals or reactive oxygen species to terminate their chain of reactions before they damage vital body molecules.

5.Perfect for healthy skin and hair

The vitamins (especially vitamin A and C) present in watermelons are crucial for skin and hair health. Vitamin C is a normal component of the skin, both in the dermis and epidermis layers. (24)

It limits damage caused by ultraviolet rays not as a sunscreen but as an antioxidant that prevents UV-induced damage by free radicals. (25)

Vitamin C also promotes wound healing because of its role in collagen formation. That collagen also keeps the skin supple and hair strong.

Vitamin A encourages healthy cell production by stimulating fibroblasts, cells that are responsible for keeping the skin firm. (26)

That explains why without enough vitamin A, the skin looks dry and flaky. It also improves acne by normalizing oil production and appearance of skin pigmentation.

6.Aids in weight loss

It may come as a surprise that watermelon is actually a good choice for bringing the weighing scale down.

Despite the fact that it is sweet and most of its calories come from sugars, it is a super healthy choice that does not pack a lot of calories per serving. (27)

That means that someone on a weight loss journey can consume a large portion without consuming a lot of calories. Also, its high-water content and a considerable level of fiber, make it a filling fruit choice. It slows digestion, keeps off the hunger pangs and cravings.

Other than diet, physical activity is also another essential part of any sustainable weight-loss plan. Cardiovascular and strength exercises help to burn fat and tone muscles as well. One major challenge when performing these exercises is muscle soreness, which is usually a result of micro-tears on muscle fibers. (28)

Citrulline when converted to arginine speeds up the muscle recovery process by increasing blood supply to the muscles. This action improves oxygen and anti-inflammatories level, which means that muscles can repair themselves faster. (29)

7.Protects nerve function

The potassium present in watermelon helps regulate nerve function by facilitating relay of electrical impulses and messages. (30)

Low potassium levels may thus cause numbing and tingling sensations. Moreover, potassium alongside sodium and calcium ensures that muscles do not cramp or fatigue easily.

A cup of watermelon has 173mg of potassium and may, therefore, be the solution for night time muscle cramps.

8.Can promote sexual health

Some sexual health experts refer to watermelon as a natural Viagra. That is because it relaxes and dilates blood vessels to the penis, making it possible to initiate and sustain an erection. (31)

As mentioned before, watermelon has citrulline, which is converted to arginine, a precursor for nitric oxide. According to a study (32)

carried out to test the efficacy and safety of citrulline in treating mild erectile dysfunction, citrulline improves erection hardness score from 3 to 4.

Although this is not as impressive as other phosphodiesterase inhibitors, it is safer and psychologically acceptable to many.

How to sprout watermelon seeds

Like oatmeal, buckwheat, chia, flaxseeds or many other varieties of seeds and grains, watermelon seeds are best eaten when sprouted. The germination process decreases the presence of anti-nutrients, which are naturally occurring compounds that interfere with the body’s ability to digest vitamins and minerals. The sprouting process therefore increases nutrient absorption, enhances nutrient availability and makes them easier to digest. (33)

To sprout watermelon seeds, start with fresh seeds. You can buy the seeds or save some from your most recent watermelon purchase. Begin by rinsing the seeds thoroughly to remove any fruit pieces or juices, then dry them completely in direct sunlight.

Next, soak the seeds overnight in water in the ratio of three parts of water to one part of seeds. Meaning that for one cup of seeds, you add three cups of water.

Once the soaking time is up, drain the water and lightly rinse the seeds. When the water is well drained, cover the seeds with a breathable mesh, cloth or lid and leave on a cool surface, away from direct sunlight.

Next, your job will be to keep on rinsing and draining after every eight hours. Then wait for 2 to 3 days or for 1 to 2-inch sprouts to grow. At that point, you will have gotten rid of the tough black shell, and you can then dry them in an oven, dehydrator, or under the sun.

Treat sprouted watermelon seeds like any other snack- dry the sprouts, add some salt and roast in the oven for that crunchy taste. They can also be used as a topping for the breakfast oatmeal porridge or salad, to make granola or eat them on their own.

Take home message

A piece of watermelon is not just a tasty treat- it is a low-calorie and nutrient-dense serving that delivers high water content and unique nutrients. All these components have good health effects that promote proper functioning of the internal organs and systems.

Reference Links
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  10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4464475/
  11. https://pdfs.semanticscholar.org/cf71/db75ea83b50a6abbc460d0c3aa619b3e43e7.pdf
  12. https://www.cdc.gov/cholesterol/ldl_hdl.htm
  13. https://www.ncbi.nlm.nih.gov/pubmed/16007998
  14. https://www.nejm.org/doi/full/10.1056/NEJM199312303292706
  15. https://academic.oup.com/ajcn/article/83/6/1265/4632969
  16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4997430/
  17. https://books.google.co.ke/books?id=igzXCwAAQBAJ&pg=PT49&lpg=PT49&dq=Watery+fruit+and+vegetables+often+contain+levels+of+minerals+and+sugar+that+mirror+this,+so+they+can+hydrate+you+more+effectively+than+water+alone.%27&source=bl&ots=Wkj_DM6U4V&sig=jFEGDNxbMIr-aNf-yfJqzITS5oQ&hl=en&sa=X&ved=2ahUKEwiB2P316-rcAhUCVhoKHTMFCb4Q6AEwCXoECAQQAQ#v=onepage&q=Watery%20fruit%20and%20vegetables%20often%20contain%20levels%20of%20minerals%20and%20sugar%20that%20mirror%20this%2C%20so%20they%20can%20hydrate%20you%20more%20effectively%20than%20water%20alone.’&f=false
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  19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908954/
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  21. https://www.ncbi.nlm.nih.gov/pubmed/12368412
  22. https://www.ncbi.nlm.nih.gov/pubmed/16087992
  23. https://www.ncbi.nlm.nih.gov/pubmed/15462130
  24. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579659/
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  26. https://books.google.co.ke/books?id=9KztuPhf3xAC&pg=PA374&lpg=PA374&dq=Vitamin+A+encourages+healthy+cell+production+by+stimulating+fibroblasts&source=bl&ots=xGVXTs2yRU&sig=_bltS9hVFoGXBW-CMW0dFcHbrC8&hl=en&sa=X&ved=2ahUKEwj19Oze–rcAhXKQo8KHSyQC_o4ChDoATADegQIBxAB#v=onepage&q=Vitamin%20A%20encourages%20healthy%20cell%20production%20by%20stimulating%20fibroblasts&f=false
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  28. https://www.beachbodyondemand.com/blog/recovery-done-right-8-ways-prevent-muscle-soreness
  29. https://pubs.acs.org/doi/abs/10.1021/jf400964r
  30. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4963920/
  31. https://www.webmd.com/erectile-dysfunction/news/20080701/watermelon-a-natural-viagra#1
  32. https://www.ncbi.nlm.nih.gov/pubmed/21195829
  33. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4325046/
  34. https://www.ncbi.nlm.nih.gov/pubmed/2692609

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