glass of fresh watermelon juice

10 Watermelon Juice Benefits and 1 Bad Side Effect

[toc]It’s always been a summertime staple, but recently it has been relegated to the background, in favor of more haute taute choices.

That’s too bad, because this vegetable has a number of health benefits, especially for men.

Vegetable? Correct. That wasn’t a typo. In fact in 2007, HB 1669 officially designated the watermelon as the official vegetable for the State of Oklahoma (1).

Though we still defy authority and continue calling it a fruit, because frankly, it’s too much of a hassle to explain that in every single article that food is mentioned! Plus, it technically is a fruit too (2).

Here are some other things you may not know about watermelon juice nutrition.

Watermelon juice health benefits

1. Among the highest lycopene foods

This natural pigment is most often associated with tomatoes and for good reason; over 85% in our diet comes from tomatoes (and by the way, those are fruits) (3). Guess what has even higher amounts?

When you compare the lycopene content of tomato versus watermelon, the former has 3025 μg per 100g while the latter has 4868 μg per 100g (4). The melon has about 60% more.

lycopene lab measurement
USDA plant geneticist measuring lycopene content in watermelon

Not many foods have this phytonutrient. To put it in perspective, using the same 100 gram measurement, the top 10 lycopene rich foods are:

  • Guava – 5204 μg
  • Watermelon – 4868 μg
  • tomatoes – 3025 μg
  • papaya – 1828 μg
  • grapefruit – 1135 μg
  • red peppers –  484 μg
  • asparagus – 30 μg
  • purple cabbage – 20 μg
  • mango –  3 μg
  • carrots –  1 μg

As you see, the amounts decline dramatically after you move past the very top foods on the list. That makes this a special benefit, you won’t even get it with exotic [and expensive] superfoods.

While the research about lycopene is still preliminary and inconclusive, it has been suggested that it may reduce the risk of prostate cancer (5) and renal cell carcinoma, which is a type of kidney cancer (6). Others are also being studied.

How much lycopene is in watermelon juice? About 20 mg per eight ounce cup.

2. May help erectile dysfunction

couple making out in bedTo be clear, Viagra is Pfizer’s brand name for the medication sildenafil citrate. That substance is not in this fruit.

However the nickname “watermelon Viagra” has been floating around, thanks to a few studies which suggest it may benefit erectile dysfunction in men.

Published in the Journal of Urology back in 2011, an Italian study found that the amino acid L-citrulline increases blood flow to the penis (7). Watermelon is among the richest natural sources of citrulline and it doesn’t have some of the nasty side effects which can occur with Viagra.

That study involved 24 men, ranging from 46 to 66 years old.

Among those receiving placebo, only 8.3% went from “mild ED” to normal function.

For those receiving this nutrient, a whopping 50% achieved normal function. For this half which was successful, they were “reported being very satisfied.” The watermelon juice benefits for men may extend beyond just the citrulline content, as it contains another useful nutrient; L-arginine.

Back in 2007 at Texas A&M University, another study found that arginine availability increased with this juice (8). That’s because citrulline can be metabolized into arginine.

Why might that also be relevant to bedroom performance? It’s well known that arginine is linked to nitric oxide production, which plays an important role in healthy blood flow to all parts of the body.

That A&M study only involved rats and the one human study isn’t enough for proof, yet the preliminary evidence suggesting a watermelon Viagra effect is promising nonetheless.

3. Citrulline content helps fitness

Continuing the topic of its high citrulline content, and how our kidneys can synthesize it into arginine, there might be athletic advantages from that, too.

male and female curling weightsSince lifting weights requires increased blood flow to the muscle, nitric oxide supplements are fairly popular with bodybuilders and some athletes. The possible side effects from them and questions of their efficacy does leave a lot of doubters.

As an alternative, it seems like L-arginine supplements would be a good option (and indeed, many use those for bodybuilding). Though some research suggests that using the precursor citrulline from watermelon actually results in higher and longer plasma levels of arginine versus taking the supplements (9).

Citrulline supplements have been found to enhance anaerobic performance and reduce muscle fatigue (10). As far as the natural citrulline in watermelon juice, there’s only one study which was published in 2016 which looked at this topic (11).

After 2 weeks of using the juice, they did conclude that it boosted nitric oxide bioavailability, but there wasn’t sufficient evidence that exercise performance was improved. That study only involved 8 men and they were described as “recreationally-active” which is not exactly what you would call fitness buffs or serious athletes.

More research needs to be done, but if citrulline supplements work, logically it seems that potent natural food sources should also have an effect. So not only may there be the erectile dysfunction benefit for this compound, but also athletic enhancement.

4. Moderate source of vitamin C

Unlike your dog or cat, humans lack the ability to naturally make vitamin C. We need to get it from what we eat and the RDA is 90 mg for adult males and 75 mg for females.

How much vitamin C is in watermelon? 8.1 mg (12). That’s around 10% of the amount you need per day.

ascorbic acid molecule chemical structureOrange juice is heavily marketed as being a good source, which is kind of a joke considering that it is destroyed during pasteurization and they add in unnatural ascorbic acid afterward. Sadly, China makes about 80% of the ascorbic acid we consume in beverages (13).

If you compare raw orange juice vs. watermelon, the orange does have about 400% more  of it naturally (14). But very few people consume fresh squeezed orange juice, given the convenience of the carton.

But you probably will have to make your own juice from the red flesh, since it’s a type that’s not normally sold at the grocery store. Sure, making it is more of a hassle, but since it’s cold-pressed the natural vitamin C content would remain.

How much vitamin C is in watermelon juice? The USDA doesn’t have an entry for that type of juice, but you should be able to base it off of the amount in the fruit, since most juicing recipes simply involve putting the chunks of it into a blender and then drinking.

There’s so little fiber, straining isn’t necessary and for that reason, you’re basically drinking the liquefied fruit. That means the nutrition facts will be the same.

An 8 ounce cup/glass will have around 240 grams of liquid. Based on that conversion, one glass of watermelon juice has 19.4 mg of natural vitamin C. That’s over 20% of the daily value for both men and women.

Vitamin C is an antioxidant, but in terms of the juice’s total free radical fighting capacity, the overall amount of antioxidants in watermelon is low according to its ORAC value.

5. Low calorie for a juice

Screw the water. Sometimes, you just need that flavored drink of some sort, to calm your sweet tooth or food craving!

A sugary can of Coke at 140 calories is not the way to address that problem.

toddler girl drinking watermelon juiceHow many calories there are in watermelon juice is less per ounce; 75 calories for an 8 ounce cup.

A standard of Coke is 12 ounces, but even their mini 8 ounce bottle lists 100 calories on the nutrition facts label. That’s 33% higher than the juice.

Orange juice? That’s higher than both at 112 calorie for 8 ounces (though still much healthier than Coke).

For weight loss, you can reduce the calorie count even further by diluting it with some water. Unlike a soft drink, this juice tastes pretty good even when you do a 50/50 water mixture. That would yield around 38 calories per 8 oz. glass… not bad at all.

It’s also a great option for your kids.

6. Weight loss support

woman standing on body scale that reads WTFSo far, men have more reasons to be excited about the citrulline. Here’s another and women in particular will appreciate it.

The BCAA leucine may get all the hype, but it has been said that citrulline is “the dieter’s amino acid.”

This is because dieting is a catch-22 when you are trying to tone up and build muscle. On one hand you need to have a calorie deficit, yet building muscle while doing so can be a lot harder.

This 2013 study only involved rats, but it found that even when they were on a low calorie diet, by supplementing with citrulline they were able to maintain muscle synthesis (15). Taking leucine alone did not achieve the same result.

Other research has suggested that citrulline might help obese pregnant women by minimizing additional buildup of white-fat (16). Normally, that type makes up 25% of the fat content in women (17).

It’s premature to claim watermelon weight loss, especially since the research was looking at citrulline outside of the food, yet it’s still encouraging news to hear.

7. Fights inflammation and arthritis

In addition to possibly offering anti-cancer properties, research has suggested that lycopene has anti-inflammatory benefits (20). That’s not the only compound though in these melons to do so, as they also contain cucurbitacin E.

At least two studies have concluded that the relatively high amount of cucurbitacin E in watermelon may be useful in combating inflammation through the blocking of COX (cyclooxygenase) enzymes (21) (22).

The term “COX inhibitor” may ring a bell, as that’s how non-steroidal anti-inflammatory drugs (NSAIDs) work.

knee x-rayThe pain medicines ibuprofen, aspirin, and naproxen (Aleve) all work by inhibiting some types of COX enzymes. Some prescriptions for arthritis like celecoxib (Celebrex) specifically target the COX-2.

We don’t like hyping research beyond what is warranted. Some claim watermelon juice as a rheumatoid arthritis cure or remedy, but we disagree. At this point research only suggests eating or drinking the juice might reduce inflammation, which is all that can be said about it.

Is watermelon alkaline or acidic? This could be another reason it may benefit inflammation. It’s an alkaline-forming food. Unprocessed whole foods are linked to less acid in the body.

As far as identifying which fall under this umbrella, it’s not always intuitive. Even acidic foods like apple cider vinegar can be alkaline forming because of how our body digests them. Generally, foods from animal sources (meats and dairy) are the opposite – they’re acid forming.

8. May reduce risk of kidney stones

The antibiotic gentamicin (branded as Garamycin) is used for respiratory tract infections, meningitis, and other horrible diseases. Like many potent antibiotics, it carries the side effect of possible kidney damage (nephrotoxicity).

diagram of human kidneysSome online sources claim that juice from watermelons will protect and “cleanse” the kidneys from toxins because of its citrullus. With gentamicin, that doesn’t appear to the the case. Despite the antioxidant properties of citrullus, it failed to help in a rat study (18).

Does that mean the recipe for a watermelon juice kidney cleanse is bogus? It sure looks that way, given that the most common recipe only calls for blended watermelon, lemon juice, mint, and optional stevia. None of those ingredients do anything special for the kidneys.

But there is at least one reason it may still work.

The kidneys are responsible for getting rid of 70% of the uric acid in your body every day (the rest is eliminated elsewhere) (19). When you regularly have high uric acid levels, the formation of kidney stones is more likely. In order to flush this out efficiently, your body needs plenty of water intake.

If you don’t have the discipline to drink adequate amounts of straight up water, then in theory, watermelon juice may be a good alternative. Not pure though because of the sugar, but as something to mix in with your water. Since it’s already 92% water to begin with, it’s a better option than sodas and processed juices.

Though to be clear, we would certainly shy away from the watermelon cleanse label, given that we can’t find scientific evidence to substantiate that its “cleansing” any better than regular water.

9. Seeds are high in protein

Did you know that watermelon seed are an excellent source of protein?

raw watermelon seedsJust 1 ounce comes in at 8 grams of protein and 158 calories (23). That’s more protein and less calories than equal weight portions of peanuts, pistachios, almonds, cashews, and walnuts, which are the best nuts for protein.

So rather than remove the seeds, you can include them in your juice if you’re using a blender to make it.

With a juicer that won’t work, because the machine will discard the seeds in the same way it discards fiber.

Saving the raw watermelon seeds and snacking on those isn’t a good alternative. Given their toughness, they can be bad for your teeth and stomach, at least for many.

You really need to blend them into a powder-like consistency in order to make their nutrients as bioavailable as possible. Check out the top 5 blenders for smoothies if your current model isn’t up to par.

10. Rich source of potassium

Aside from the fact that it is an essential mineral we need for basic functions in our body, getting healthy amounts of potassium are important for optimal muscle function.

protein shake with bananas, oats, peanut butterFor this reason, many people use a banana post-workout in their shake or smoothie, assuming it’s among the top sources of potassium. That’s not true, banana actually ranks as #283 in the USDA’s National Nutrient Database for potassium content.

Given that the protein in bananas is almost zero, you may be better off blending whole watermelon with the seeds intact. Not only will you be getting the protein in your juice, but also the benefits of potassium.

So how does the potassium content compare versus bananas? It has less, but still a respectable amount.

An 8 ounce glass of juice from the watermelon will have around 270 mg.

A medium banana has more at 422 mg, but you’re not getting all the other health benefits mentioned above. Most men would prefer those over the higher potassium!

One potential side effect

Think twice before you guzzle a gallon of the juice. Yes, there’s plenty of nutrition, but its Achilles heel is the sugar content.

diabetes testing meterIt’s impact on blood sugar is only amplified due to the fact that it has almost no fiber, so you digest it rapidly.

Using a 120 gram serving (approximately 4 ounces), watermelon has a Glycemic Index (GI) of 72. Low glycemic food are those which score 55 and below, so that squarely puts it within the “high” category (24).

The good news is that serving size only has 6 grams of carbs, which calculates out to a glycemic load of 5… that’s low.

It’s not the glycemic index, but rather the load which paints a more accurate picture as to how it will affect blood sugar (especially in diabetics).

There is no reputable source which has measured the glycemic index and load of watermelon juice, but given that the sugar is absorbed faster (since the fiber has been blended or even strained), the number will be higher. If you have diabetes, drinking a large glass might really mess with your blood glucose levels.

Plus, that was only for a 120 gram serving of the fresh fruit, while an 8 ounce (240 gram) glass of juice is twice the amount.

Even though it tastes much sweeter, juice made from this melon actually has fewer grams of sugar than oranges, so it’s not like it’s the worst offender. Though we’re not the biggest fans of OJ (in excess) for the same reason.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.