Watermelon is so much more than just a highly refreshing summertime treat. From the perspective of a growing body of clinical research, it is a truly medicinal food.
Only this month, research published in the Journal of Agricultural and Food Chemistry found watermelon juice is an effective remedy for reducing the recovery heart rate and muscle soreness in athletes who were given 500 ml of watermelon juice (16.9 oz) containing 1.17 grams of the naturally occurring amino acid L-citrulline.
Additional research indicates watermelon may possess the following health benefits:
- Boosting Your Antioxidant Levels: Watermelon is exceptionally rich in lycopene (hence its red color) and other carotenoids such as lutein and beta carotene. A 2003 study published in the Journal of Nutrition found that regular watermelon juice consumption resulted in significant increases in blood plasma concentrations of lycopene and beta carotene. Keep in mind that lycopene has been found to have over 40 potential health benefits, and beta carotene (especially in its natural, food-complexed form) equally plentiful health benefits, adding extra significance to this finding. Also, the watermelon-induced increase in plasma antioxidant levels may lend explanation to why an epidemiological study of the Chinese found greater watermelon intake to be associated with a lower risk of cancer.
- Reducing Blood Pressure/Improving Arterial Health: A 2012 study published in the American Journal of Hypertension found that middle-aged obese subjects with prehypertension or stage 1 hypertension who were given 6 weeks of treatment with a watermelon extract containing 6 grams of L-citrulline and L-arginine daily, experienced reduced ankle blood pressure and altered carotid wave reflection, an indication of improved arterial function. The inability of the blood vessels to dilate and function properly is known as endothelial dysfunction, and is likely the most well-known initiating step in the pathogenesis of atherosclerosis. If watermelon can ameliorate or reverse this process, it would certainly provide a breakthrough alternative to many of the drugs used for primary prevention, such as the cholesterol-lowering statin drug class, whose side effects, numbering in the hundreds, include heart muscle dysfunction and damage.
- Increasing Plasma Arginine Concentrations: A 2007 study published in the journal Nutrition found that watermelon juice consumption increases plasma arginine concentrations in adults, proving that the L-citrulline from this plant origin was effectively converted into arginine. This is a highly significant finding because arginine has a great number of health benefits, especially for ameliorating the aforementioned cardiovascular problem known as endothelial dysfunction. There are at least 20 studies in the biomedical literature documenting its therapeutic role in improving endothelial dysfunction, but you can view over 150 potential health benefits of arginine on the GreenMedInfo database.
- Combatting Metabolic Syndrome: A promising preclinical study published in the Journal of Nutrition in 2007 found that watermelon pomace, a rich source of L-citrulline, significantly improved metabolic syndrome in diabetic, overweight rats. This study is of particular interest because it lends support to relatively new research showing that fruit consumption is not harmful for type 2 diabetics. The new study results were described as follows: ” These results provide the first evidence to our knowledge for a beneficial effect of watermelon pomace juice as a functional food for increasing arginine availability, reducing serum concentrations of cardiovascular risk factors, improving glycemic control, and ameliorating vascular dysfunction in obese animals with type-II diabetes.”
- Watermelon Seeds, a Rich Source of Protein: It behooves us to mention the fact that all parts of the watermelon have something to offer. The seeds, in fact, are an excellent source of protein. A 2011 study published in the Journal of Cancer Research and Clinical Oncology found that “The good nutritional and functional properties of watermelon seed meal proteins suggest their potential use in food formulations.” While seedless watermelon are far more convenient to eat, keep in mind that they can not reproduce without human intervention and so there are several good reasons to choose seeded varieties.
So, next time you are in the mood for watermelon, and are concerned about its notorious sugar content, ‘weight-promoting effects,’ and therefore possible diabetogenic and cardiotoxic properties – think again. Quality and moderation are the only things to make sure you are careful about when deciding to consume watermelon. Otherwise, enjoy it (remember Vitamin P(leasure))and know that it may just be as good for you as it tastes.
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 U G Chandrika, K S S P Fernando, K K D S Ranaweera. Carotenoid content and in vitro bioaccessibility of lycopene from guava (Psidium guajava) and watermelon (Citrullus lanatus) by high-performance liquid chromatography diode array detection. Int J Food Sci Nutr. 2009 Nov;60(7):558-66. PMID: 19817635
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 Guoyao Wu, Julie K Collins, Penelope Perkins-Veazie, Muhammad Siddiq, Kirk D Dolan, Katherine A Kelly, Cristine L Heaps, Cynthia J Meininger. Dietary supplementation with watermelon pomace juice enhances arginine availability and ameliorates the metabolic syndrome in Zucker diabetic fatty rats. J Nutr. 2007 Dec;137(12):2680-5. PMID: 18029483
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 Ali Abas Wani, Dalbir Singh Sogi, Preeti Singh, Idrees Ahmed Wani, Uma S Shivhare.Characterisation and functional properties of watermelon (Citrullus lanatus) seed proteins. J Cancer Res Clin Oncol. 2011 Feb;137(2):279-86. Epub 2010 Apr 18. PMID:20824684
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