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August 1, 2013 by MAE CHAN
High Levels of Amino Acid in Watermelon Improve Sports Performance, Soothe Sore Muscles, But Investigate Your Source

Watermelon is known to play a role in improving cardiovascular health, but watermelon juice also has 'excellent'potential as a functional drink to relieve sore muscles in athletes due to high levels of amino acid L-Citrulluine, a new Spanish study testing cyclists reports.

A pilot study in 2010 showed that watermelon extracts may be effective at naturally reducing pre-hypertension. The research, led by food scientists at The Florida State University suggested that 6 weeks of L-citrulline extract from watermelon, reduced blood pressure and aortic wave reflection in middle aged individuals with pre-hypertension.

Another study from Purdue University and University of Kentucky showed that mice fed a diet including watermelon juice had lower weight, cholesterol and arterial plaque than a control group.

Scientists have said that watermelon has ingredients that deliver Viagra-like effects to the body’s blood vessels and may even increase libido. "The more we study watermelons, the more we realize just how amazing a fruit it is in providing natural enhancers to the human body," said Dr. Bhimu Patil, director of Texas A&M’s Fruit and Vegetable Improvement Center in College Station.

This presupposed adequate bioavailability of L-Citrulluine, which occurs at highest levels in watermelons (it also occurs in other melons, squashes, cucumbers and pumpkins) and can be biosynthesized by the human body using other sources.

"This amino acid could be supplied as watermelon juice or as products enriched in citrulline from watermelon extraction. In both cases, it is important to choose watermelon cultivars rich in this amino acid," Tarazona-Diaz et al. write.

Little interest, until now...

Until recently, the authors add, L-Citrulluine attracted little interest among the nutrition community, due to its status as a non-protein amino acid viewed solely as a metabolic intermediary in the urea cycle.

Introducing their study, the team say its antioxidant properties and ability to generate nitric oxide made it a good candidate for treating conditions such as hypertension, heart failure, atherosclerosis.

Previous studies show it might also be used to treat sickle cell disease and sexual stamina and erectile functions, they add, while other benefits associated with L-Citrulluine intake include better athletic performance due to nitric oxide synthesis and better glucose transport in skeletal muscle.

The current study involved maximum effort test using a cycloergometer by seven healthy University of Mercia sports science students (average age 22.7, standard deviation, +/- 0.8 years).

On three separate occasions, each athlete drank 500ml of natural watermelon juice (1.17g of L-Citrulluine), enriched watermelon juice (4.83g of L-Citrulluine plus 1.17g from watermelon) and a placebo.

No difference in perceived exertion

Drinking the juice in both forms did not significantly improve pedalling cadence (measured in RPM) or heart rate, the scientists found, with the latter tested at the start/end of the test and during a recovery period.

There were no differences in perceived exertion, but muscle soreness 24 hours after exercise was significantly greater when cyclists drank the placebo, while results for the standard and enriched juices did not differ, indicating that 1.17g of L-Citrulluine was sufficient amino acid to help reduce physical soreness.

Watermelon Healthiest When Served Warm

The amount of lycopene in watermelons goes up about an average of 20 percent when we left them out uncut at room temperature, while beta carotene actually doubles.

Like tomatoes, the red flesh of watermelons owes its coloring to an abundance of lycopene, an organic pigment from the carotenoid family that ranges in shade from pale yellow to deep red.

While it is known that light, temperature and moisture changes which occur during harvesting and packaging can alter a watermelon's lycopene content by 10 percent to 20 percent, researchers have realized that little was known about the impact storage can have once the heavy fruit is in the kitchen.

Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas said " can leave certain fruits sitting out," she added. "If you're not going to eat it right away, they don't have to be taking up space in your fridge. In fact, there are several fruits that ripen better when left out -- peaches, bananas -- that not only end up having better nutrient quality but also perhaps better taste."

"If it's cut, you want to leave it in the fridge," she advised. "If it's uncut, it's perfectly alright to leave it on the counter for a day or two, and if you like cold watermelon -- which a lot of people do -- it's perfectly alright to put it in the fridge to let it cool down a little before eating it."

Beware of White seeds in Watermelons

Most watermelons sold at wholesale markets are believed to have been treated with forchlorfenuron. Telltale signs are fibrous, misshapen fruit with mostly white instead of black seeds.

Forchlorfenuron is a cytokinin, that is, it's a substance that promotes cell division and delays cell death. FCF acts on septins, which are key factors in mitosis, cell division. That function results in larger--and exploding--fruit. The application of excess FCF prompts cells to divide more rapidly. That's a cancer-like function.

Of course, the greater multiplication of cells produces bigger fruits, but that excess growth is not necessarily accompanied by adequate nutrients. Therefore, the stability and nutritional quality of the fruit tends to deteriorate.

According to the U.S. Environmental Protection Agency's Pesticide Fact Sheet, forchlorfenuron causes inflammation, growth retardation, emaciation, and increased mortality in rats tested.

In NTDTV's exclusive, a farmer, Liu Mingsuo is profiled after counting his losses when his watermelon crops began exploding on the ground. He says a local agricultural expert advised him to spray his crops with a type of chemical. It's supposed to make the melons grow bigger and taste sweeter. But in a bizarre twist, the watermelons began bursting open, well before they were ripe. In just one morning, Liu had to throw out more than 11,000 pounds of his crops.

An investigative report by China Central Television found farms in and around Danyang city in Jiangsu province were losing acres of fruit to the problem.

The farmers spray forchlorfenuron, a growth accelerator, during overly wet weather which make the melons burst, CCTV said, citing agricultural experts. Readers should be aware that forchlorfenuron is also registered for use on grapes raisins, and kiwi fruit in the United States, Chile, Egypt, Israel, Mexico, New Zealand, South Africa, Turkey, Canada and Europe.

Journal of Agricultural and Food Chemistry

EPA Pesticide Fact Sheet
APVMA Forchlorfenuron eval

Mae Chan holds degrees in both physiology and nutritional sciences. She is also blogger and and technology enthusiast with a passion for disseminating information about health.

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