Watermelon for hydration and vitality

 

“When one has tasted it, he knows what the angels eat.”

Mark Twain, Pudd’nhead Wilson (Hartford, Conn.: American Publishing Company, 1894).

Watermelon (Citrullus lanatus), with its vibrant red flesh and refreshing taste, has been a favourite summer fruit for centuries. Originating from Africa, this gourd has become a symbol of hydration and vitality. Its high water content and sweet flavour make it a versatile treat for dogs, fresh or in ices or smoothies. Beyond its refreshing taste, watermelon is packed with nutrients that can offer a variety of health benefits, making it a valuable summer addition to the hydrating ingredients in the Well Dog Pantry. In fact, it’s a bit of a superfood. There’s a Turkish proverb: “Two watermelons cannot be held under one arm.” But they contain so much goodness, why try and carry two anyway?

Main Nutrients

Water Content

Being composed of about 90% water, watermelon is an incredibly hydrating fruit. This high water content is particularly beneficial for dogs, especially during hot weather or after intense physical activity. Staying well-hydrated is crucial for maintaining a dog’s overall health, supporting kidney function, and regulating body temperature. (See Hydrate, Hydrate, Hydrate.)

Dietary Fibre

Although watermelon contains only a moderate amount of dietary fibre, it is considered a high-FODMAP food. FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) are a group of short-chain carbohydrates that are resistant to digestion. They are fermented in the gut and used to feed gut bacteria, which is beneficial. However, the gases produced may be problematic if watermelon is consumed in large quantities. Therefore, while this fruit can provide beneficial fibre, it should be introduced gradually and in moderation, particularly for dogs with digestive sensitivities.

Antioxidants

Watermelon is a source of antioxidants such as lycopene (responsible for the pigmentation of watermelon), beta-carotene, and vitamin C. Consumption of watermelon has been shown to improve antioxidant capacity[1]. Beta-carotene in particular is likely to protect immune cells against mitochondrial dysfunction, which can lead to problems like reduced energy, increased oxidative stress and cellular damage[2].

Amino acids
Citrulline and arginine

Watermelon is one of the few fruits that contain citrulline. Citrulline, which alongside lycopenes and polyphenols is abundant in watermelon, is converted into arginine. Arginine plays a crucial role in various physiological processes.  Arginine supports the production of nitric oxide, which helps to improve blood flow. This is particularly beneficial for cardiovascular health and can also aid in muscle recovery and endurance. Arginine has also been shown to have potential antidiabetic properties[3].

Main Vitamins

Vitamin A

Watermelon contains beta-carotene, which the body can convert into vitamin A. This vitamin is essential for maintaining healthy vision, supporting immune function, and promoting skin and coat health in dogs.

Vitamin C

As an important antioxidant, vitamin C in watermelon supports the immune system by helping to fend off infections and illnesses. It also plays a role in collagen synthesis, which is important for maintaining the health of skin, joints, and connective tissues.

Minerals

Potassium

Watermelon is a source of potassium, a mineral that is vital for maintaining proper heart function and muscle contractions. Potassium also helps regulate fluid balance and blood pressure.

Benefits – Key Takeaways:

Hydration and Kidney Health

The high water content in watermelon makes it an excellent hydrating treat for dogs, especially in hot weather or after exercise. Adequate hydration is key to maintaining healthy kidney function, flushing out toxins, and preventing urinary tract infections. (One study[4] showed that over time, daily consumption of a watermelon beverage reduced serum leptin levels and inhibited the formation of urinary stones.)

Immune Support

The antioxidants present in watermelon, including vitamin C and beta-carotene, help boost the immune system by neutralising free radicals and reducing oxidative stress. This is crucial for protecting dogs from infections, diseases, and age-related conditions. Regular consumption of antioxidant-rich foods like watermelon can contribute to a stronger immune response and overall health.

Heart Health and Blood Flow

Potassium and citrulline in watermelon contribute to cardiovascular health by supporting proper heart function and improving blood circulation. Potassium helps regulate blood pressure, while citrulline, by promoting the production of nitric oxide, can enhance blood flow. This is consequently particularly beneficial for active dogs or those prone to cardiovascular issues.

Weight Management

Watermelon is low in calories but high in water content, making it an ideal snack for dogs who need to manage their weight. Consumption of the flavonoids in fruits such as watermelon have been shown in several studies to reduce fat weight[5]. In humans, daily consumption of watermelon was shown to improve BMI and lead to a decrease body weight and measurements[6].

Antidiabetic Benefits

Watermelon contains several compounds that may offer antidiabetic benefits, particularly due to its content of lycopene and citrulline. Lycopene, an antioxidant, has been studied for its potential role in improving insulin sensitivity and reducing oxidative stress, which are important factors in managing diabetes. Additionally, citrulline in watermelon can help improve blood circulation and may play a role in reducing blood sugar levels by enhancing the production of insulin. Based on their results in animal testing, Wu et al.[7] recommended watermelon pomace juice as a functional food to combat obesity and diabetes.

Reminder:

The bacteria that gobble up the FODMAPs produce gas and can lead to constipation or diarrhoea so it is important not to overfeed watermelon. (Low FODMAP diets have proved beneficial for bowel disorders such as IBS.)
Remove seeds before feeding watermelon to your dog.

Ideas:

  • You can freeze small cubes of watermelon to be given as a hydrating treat throughout the day.
  • Try incorporating watermelon in ices with other fruits and kefir.

References:

[1] Hong MY, Hartig N, Kaufman K, Hooshmand S, Figueroa A and Kern M, 2015. Watermelon consumption improves inflammation and antioxidant capacity in rats fed an atherogenic diet. Nutr Res. Vol. 35, No. 3, pp: 251–258, doi: 10.1016/j.nutres.2014.12.005.
[2] Chew, B. P., Park, J. S., Weng, B. C., Wong, T. S., Hayek, M. G. & Reinhart, G. A.(2000) Dietary b-carotene is taken up by blood plasma and leukocytes in dogs. J. Nutr. 130.
[3] Jelodar G, Razmi N, Gholapour V. Arginase alteration in the reproductive system of alloxan-diabetic dogs. J Reprod Dev. 2007;53:317–321.
[4] Sayaka Miyai, Toshiharu Hashizume, Toshio Okazaki. (2018). Effects of a Watermelon Extract Beverage on Canine Lipid Metabolism and Urine Crystals. Animal and Veterinary Sciences, 6(5), 74-79. https://doi.org/10.11648/j.avs.20180605.12
[5] Okazaki T, Hashizume T , Suzuki M and Ogawa Z, 2014. Anti-obesity effects of watermelon extract on rats fed high-fat diet. Journal of Pet Animal Nutrition. Vol. 17, No. 1, pp. 13–18, doi: https://doi.org/10.11266/jpan.17.13.
[6] Connolly, M.; Lum, T.; Marx, A.; Hooshmand, S.; Kern, M.; Liu, C.; Hong, M.Y. Effect of Fresh Watermelon Consumption on Risk Factors for Cardiovascular Disease in Overweight and Obese Adults (P06-102-19). Curr. Dev. Nutr. 2019, 3.
[7] Wu, G.; Collins, J.K.; Perkins-Veazie, P.; Siddiq, M.; Dolan, K.D.; Kelly, K.A.; Heaps, C.L.; Meininger, C.J. Dietary supplementation with watermelon pomace juice enhances arginine availability and ameliorates the metabolic syndrome in Zucker diabetic fatty rats. J. Nutr. 2007, 137, 2680–2685.

 

Want to know more? These studies may be useful:

  • Manivannan A, Lee ES, Han K, Lee HE, Kim DS. Versatile Nutraceutical Potentials of Watermelon-A Modest Fruit Loaded with Pharmaceutically Valuable Phytochemicals. Molecules. 2020 Nov 11;25(22):5258. doi: 10.3390/molecules25225258. PMID: 33187365; PMCID: PMC7698065.
  • Tamburini E, Costa S, Rugiero I, Pedrini P and Marchetti MG, 2017. Quantification of lycopene, β-carotene, and total soluble solids in intact red-flesh watermelon  (citrullus lanatus) using on-line near-infrared spectroscopy. Sensors (Basel).  Vol.  17, No. 4, pii: E746, doi: 10.3390/s17040746.

Nutritional information:

Watermelon, raw, 100 g

 

For full nutrient content see Food Data Central

 

Important Considerations:

  • Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
  • If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
  • Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
  • Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
  • I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
  • Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.