The Seeds of Summer
Watermelon juice has demonstrated some surprising activity relevant to male fertility in lab studies.
Greetings from the very hot southeast USA! Temperatures have regularly hit over 90°F! We’re lucky to have a neighborhood pool just a block from our house—a refuge from the worst heat of the day. Staying hydrated is also a priority, and like many families, mine has been enjoying the red watery deliciousness of watermelon! I've eaten quite a large share of this sweet treat over the past couple of weeks, so when brainstorming a seasonal plant to write about this week, Citrullus lanatus (the scientific name for watermelon) came to mind immediately.
When I think of watermelon, it is usually in the context of food and culture. My hometown of Arcadia, Florida, has always been a big producer of this fruit, and we celebrated the harvest each year with a Watermelon Festival—complete with a parade, seed-spitting and speed-eating contests, and even a beauty pageant! But this is a newsletter about medicinal plants—Nature’s Pharmacy. Does watermelon offer any benefits to human health beyond providing hydration? The answer is yes, and the specific health benefits will likely surprise you as much as they did me! But first, let’s take a look at the history of this fruit.
Botanical History
Watermelons (Citrullus genus in the Cucurbitaceae plant family) are native to Africa and have a long history of cultivation. Ancient wild watermelons had watery but typically hard-textured, pale-colored, and often bitter or bland flesh. The familiar sweet watermelon we are most familiar with, Citrullus lanatus, with its non-bitter, tender, and red colored flesh, is thought to originate from selective breeding in a single ancestral population. This transformation from the wild to the sweet dessert variety is suggested by their narrow genetic base.
Did you know? Over 3.4 million hectares of land are planted with watermelons each year, producing more than 102 million tons of this tasty fruit.
Archaeological findings indicate that watermelons have been cultivated for at least 5,000 years, with seeds found in northeastern Africa and images of the fruit in Egyptian tombs dating back at least 4,000 years. Historical texts from Greek, Latin, and Hebrew sources from the first centuries CE describe large, thick-rinded, watery fruits, which are identified as watermelons. Evidence points to northeastern Africa as the origin of the sweet dessert watermelon, domesticated over 4,000 years ago and spreading to Mediterranean regions about 2,000 years ago.
Pharmacological Properties
In addition to being a delicious food, there are many uses for watermelon in traditional medicine. For example, one review article highlighted that:
Watermelon rinds are used therapeutically for conditions involving alcohol intoxication and diabetes.
High potassium content in watermelon helps treat potassium deficiency and kidney stones.
Watermelon seeds have antihypertensive properties, useful for reducing blood pressure.
In Northern Sudan, watermelon is used to treat burns, swelling, rheumatism, and gout, and as a laxative.
Watermelon consumption is used in traditional medicine to treat cardiovascular disease and some studies suggest it may reduce risk of age-related neurodegenerative disorders and certain cancers.
Did you know? The red color of watermelon flesh is due to the rich quantities of lycopene, the same antioxidant compound found in tomatoes that imparts their red color!
Beyond these ethnopharmacological uses, what caught my interest in the review were the studies undertaken on the impact of watermelon on male fertility. A number of studies have evaluated the effect of watermelons on male fertility in animal models, demonstrating that it “improves seminal quality, reverses erectile dysfunction, and improves testicular redox status and gonadotropin secretion.”
What about humans? As we know, an animal study does not always directly translate to what happens in a human. I found a secondary note to the editor of a journal that highlighted findings from their study in 20 individuals who consumed 16 ounces of watermelon juice daily and who showed “decreased sperm membrane lipoperoxidation, intracellular production of reactive oxygen species, DNA fragmentation index on day 15 and antioxidant capacity on days 7 and 15.” Unfortunately, the original study (published in a Spanish language journal) couldn’t be found online and I wasn’t able to assess the rigor of the experimental setup or findings.
So, for now, what do we know? We know that in rodents, there are some promising improvements in reduced oxidative damage and improved seminal quality following regular consumption of watermelon.
What do we not know? We don’t know if and how this might work to improve male fertility in humans. But this is certainly an area of research that should be further explored!
The Takeaway
Whether or not watermelon can give a boost to male fertility in humans, it remains a delicious and nutritious food item packed with antioxidants. I hope you have the chance to enjoy a cooling slice of melon this July 4th holiday!
Yours in health, Dr. Q
Cassandra L. Quave, Ph.D. is a Guggenheim Fellow, CNN Champion for Change, Fellow of the National Academy of Inventors, recipient of The National Academies Award for Excellence in Science Communication, and award-winning author of The Plant Hunter. Her day job is as professor and herbarium curator at Emory University School of Medicine, where she leads a group of research scientists studying medicinal plants to find new life-saving drugs from nature. She hosts the Foodie Pharmacology podcast and writes the Nature’s Pharmacy newsletter to share the science behind natural medicines. To support her effort, consider a paid or founding subscription or donation to her lab research.
Watermelon is a favorite in our house. I recall being told that it is useful as a diuretic. Is this true?
Are you aware of any studies? Thanks