6 Things You Didn't Know About Watermelon
July 21, 2014 |
By Dr. Mercola
Story at-a-glance +
· Watermelon
contains more of the antioxidant lycopene than fresh tomatoes; one cup
of watermelon has 1.5 times the lycopene as a raw tomato
· L-citrulline, an amino acid in watermelon, seems to protect against muscle pain
· Watermelon
rind is edible and actually contains more of the amino acid citrulline
than the pink flesh; citrulline is converted to arginine in your
kidneys, which is important for heart and immune system health
· New
research showed citrulline and arginine supplements derived from
watermelon extract lead to significant improvements in blood pressure
and cardiac stress in obese study participants
· Watermelon
contains cucurbitacin E, or tripterpenoid, which blocks the activity of
the pain and inflammation-causing enzyme cyclooxygenase -- the same
enzyme blocked by COX-2 inhibitor drugs
By Dr. Mercola
In
the US, July is National Watermelon Month, so named not only because a
cool, refreshing slice of watermelon represents the epitome of summer,
but also because watermelon harvests peak this month.1
Watermelon
is now the most-consumed melon in the US (followed by cantaloupe and
honeydew). This cousin to cucumbers, pumpkins, and squash is thought to
have originated in Egypt close to 5,000 years ago, where it is depicted
in hieroglyphics.
Today, upwards of 300 watermelon varieties are grown in the US and Mexico (although only about 50 are popular).2
You may think you know everything there is to know about this
summertime fruit, but allow me to surprise you… watermelon is more than
just delicious… it’s a super-healthy addition to your diet (in
moderation, of course).
You just need to be careful when eating any melon, including watermelon to follow the advice of Wayne Pickering in my interview.
Eat melon alone or leave it alone because it will make your stomach
groan. So ideally, no food 30 minutes before or after eating melons.
6 Watermelon Facts That Might Surprise You
1. Watermelon Has More Lycopene Than Raw Tomatoes
Lycopene is a powerful carotenoid antioxidant that gives fruits and vegetables a pink or red color. It’s most often associated with tomatoes, but watermelon is actually a more concentrated source.
Compared
to a large fresh tomato, one cup of watermelon has 1.5 times the
lycopene (6 milligrams (mg) in watermelon compared to 4 mg in a tomato).3 More on why lycopene is so important shortly…
2. Watermelon Juice May Relieve Muscle Soreness
If
you have a juicer, try juicing about one-third of a fresh watermelon
and drinking its juice prior to your next workout. This contains a
little over one gram of l-citrulline, an amino acid that seems to
protect against muscle pain.
One
study found that men who drank natural unpasteurized watermelon juice
prior to their workouts had reduced muscle soreness 24 hours later
compared to those who drank a placebo.4
You
do need to be careful with drinking watermelon juice, though, as it
contains a significant amount of fructose. It may be better to eat the
entire fruit, or opt for these other tips to prevent muscle soreness.
3. Watermelon Is a Fruit and a Vegetable
Remember
how watermelon is related to cucumbers, pumpkin, and squash? That’s
because it’s part vegetable and part fruit (it’s a sweet, seed-producing
plant, after all).5 The other clue that watermelon is both fruit and vegetable? The rind is entirely edible…
4. You Can Eat Watermelon Rind and Seeds
Most people throw away the watermelon rind, but try putting it in a blender with some lime for a healthy, refreshing treat.6
Not only does the rind contain plenty of health-promoting and
blood-building chlorophyll, but the rind actually contains more of the
amino acid citrulline than the pink flesh.7
Citrulline is converted to arginine in your kidneys, and not only is this amino acid important for heart health
and maintaining your immune system, but it has been researched to have
potential therapeutic value in over 100 health conditions.8
While
many people prefer seedless watermelon varieties, black watermelon
seeds are edible and actually quite healthy. They contain iron, zinc,
protein, and fiber. (In case you were wondering, seedless watermelons
aren’t genetically modified, as they’re the result of hybridization.9)
5. It’s Mostly Water
This might not be surprising, but it’s still a fun fact; watermelon is more than 91 percent water.10
This means that eating watermelon with you on a hot summer day is a
tasty way to help you stay hydrated and avoid dehydration (it’s not a
substitute for drinking plenty of fresh water, however).
6. Some Watermelon Are Yellow
The
Yellow Crimson watermelon has yellow flesh with a sweeter, honey flavor
than the more popular pink-fleshed Crimson Sweet. It’s likely that
yellow watermelon offers its own unique set of nutritional benefits, but
most research to date has focused on the pink-fleshed varieties.11
Lycopene: Watermelon’s Nutritional Claim to Fame
Watermelon
is an excellent source of lycopene, with upwards of 6,500 micrograms
(6.5 mg) in less than half a cup (the red-fleshed varieties will contain
significantly more lycopene than yellow-fleshed watermelon).
Also
noteworthy, the lycopene in watermelon appears to be quite stable, with
little deterioration occurring even after it’s been cut and stored in
the refrigerator for more than two days. In one study, it took about
seven days of storage for the lycopene to deteriorate, and then it was
only by about 6 percent to 11 percent.12
So
what makes lycopene so important? Lycopene's antioxidant activity has
long been suggested to be more powerful than that of other carotenoids,
such as beta-carotene. In one study, after controlling for other stroke
risk factors, such as older age and diabetes, they found that men with
the highest blood levels of lycopene were 55 percent less likely to have
a stroke than those with the lowest.13
A
2014 meta-analysis also revealed that lycopene decreased stroke risk
(including stroke occurrence or mortality) by more than 19 percent.14 In addition to lowering your risk of stroke, lycopene has been shown to have potential anti-cancer activity, likely due to its potent antioxidant properties.
A
2014 meta-analysis of 10 studies also showed that dietary lycopene may
protect against the risk of ovarian cancer among postmenopausal women.15 There is also some evidence from animal studies that lycopene may help with cancer treatment as well.
One
study found that lycopene treatment reduced the growth of brain tumors
while another showed frequent lycopene intake suppressed breast tumor
growth in mice.16
Watermelon Extract May Significantly Reduce Blood Pressure
New
research also highlights the role of watermelon nutrients on heart
attack prevention, via a significant reduction in blood pressure. Obese
study participants who received citrulline and arginine supplements
derived from watermelon extract had significant improvements in blood
pressure and cardiac stress, both while at rest and undergoing a
stressful cold-water test.17 According to the researchers:
“Watermelon
supplementation reduced aortic BP [blood pressure] and myocardial
oxygen demand during CPT [cold pressor test] and the magnitude of the
cold-induced increase in wave reflection in obese adults with
hypertension. Watermelon may provide cardioprotection by attenuating
cold-induced aortic hemodynamic responses.”
Remember,
in your body the citrulline in watermelon is converted into L-arginine,
which is a precursor to nitric oxide. Adequate nitric oxide is required
to enable you blood vessels to stay relaxed and open for blood flow,
which is one reason why it may help lower blood pressure.
Watermelon for Inflammation, Sexual Health, and More
L-arginine may also help with erectile dysfunction
by helping to relax your blood vessels, including those supplying blood
to your penis – and that’s why watermelon is sometimes referred to as
“Nature’s Viagra.” In fact, citrulline supplementation has been found to
improve erection hardness in men with mild erectile dysfunction.18
What else is watermelon good for?
It’s rich in anti-inflammatory substances. For instance, watermelon
contains the anti-inflammatory antioxidant lycopene as well as
cucurbitacin E, or tripterpenoid, which reduces the activity of the pain
and inflammation-causing enzyme cyclooxygenase – the same enzyme
blocked by COX-2 inhibitors, which include most NSAIDs like aspirin and
ibuprofen. While being very low in calories (about 46 calories in a
cup), watermelon also contains an impressive variety of other important
nutrients in which many Americans are lacking, including:
· Vitamin C
· Vitamin B6
· Potassium
· Vitamin A
How to Pick the Perfect Watermelon
Cutting
into a watermelon and finding out it lacks flavor is disappointing.
There’s a trick you can use to pick out a ripe watermelon, either from
your farmer’s market or your own melon patch. Look for a pale,
buttery-yellow spot (not white or green) on the bottom. This is where
the watermelon sits on the ground ripening, and it’s one of the best
indicators of ripeness you can use (even commercial watermelon pickers
use this as a gauge).19 Other tricks for picking a ripe watermelon include:
· Should be heavy for its size
· Smooth rind with a dull top (the top is the side opposite the ground spot)
· The thump test (this is controversial, but ripe watermelon is said to have a hollow bass sound)
Store
your watermelon in a cool area (50-60 degrees F) until it’s cut. Cut
watermelon should be refrigerated (and be sure to wipe off your
watermelon with a damp cloth prior to cutting it). Remember, try the
rind blended with some lime juice rather than simply tossing it in the
trash (choose an organic watermelon especially if you’ll be eating the
rind). Finally, watermelon should be enjoyed in moderation due to its
fructose content. One-sixteenth of a medium watermelon contains 11.3
grams of fructose (I recommend keeping your total
fructose intake below 25 grams of fructose per day if you're in good
health, and below 15 grams a day if you’re overweight or have high blood
pressure or diabetes).
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