Supports kidney function
According to data from the U.S. Department of Agriculture , watermelon contains approximately 90-92% water, making it one of the most effective fruits for hydration. Eating watermelon daily contributes to increased fluid intake, thereby helping to maintain adequate hydration.
Staying adequately hydrated helps the kidneys perform their functions of filtering blood and producing urine effectively – two crucial activities for maintaining the health of this organ. Thanks to its high water content, watermelon also acts as a natural diuretic, contributing to maintaining fluid and electrolyte balance.
It may lower blood pressure.
High blood pressure is one of the leading causes of chronic kidney disease. Watermelon contains L-citrulline, an amino acid that is metabolized into L-arginine. These two compounds are precursors to nitric oxide, which helps dilate blood vessels, improve blood circulation, and contribute to lowering blood pressure.
According to research by Dutch scientists published in Cambridge Press , consuming watermelon significantly reduces systolic blood pressure. Since high blood pressure can damage the small blood vessels in the kidneys—which are responsible for filtering blood—better blood pressure control may indirectly protect kidney function.
Reduce oxidative stress
Watermelon provides lycopene, vitamin C, carotenoids, and many bioactive compounds with antioxidant properties, limiting oxidative stress.
Oxidative stress is a contributing factor to an increased risk of cardiovascular disease and chronic kidney disease. However, current clinical trials have not proven that eating watermelon can directly prevent kidney disease.
Some experimental studies suggest that flavonoids may support the body's natural antioxidant system, rather than simply neutralizing free radicals. However, more human studies are needed to confirm this effect.
It may be harmful to people with kidney failure.
Although not classified as a potassium-rich fruit, watermelon has been linked to hyperkalemia.
Approximately 155g of watermelon contains 174mg of potassium. For people with healthy kidneys, this amount of potassium is usually excreted efficiently. Conversely, people with impaired kidney function may have difficulty eliminating excess potassium.
People with moderate to severe chronic kidney disease or those undergoing dialysis should consult their doctor before eating watermelon daily. They may need to restrict potassium because damaged kidneys cannot efficiently excrete this mineral, increasing the risk of hyperkalemia. This condition can cause muscle weakness, heart rhythm disturbances, and in severe cases, cardiac arrest.
People who are taking medications that increase blood potassium levels, especially those with impaired kidney function, should also consult their doctor before eating watermelon regularly.