Parsley (Petroselinum crispum) has a long history of traditional use in supporting kidney health and urinary function. In various folk medicine systems, especially in Mediterranean and Middle Eastern cultures, parsley has been used as a diuretic ("water pill") to promote urination and help flush the kidneys. Herbalists have recommended parsley for the management of kidney stones, urinary tract infections, and general kidney "cleansing."

Some of these traditional uses are attributed to parsley’s high content of volatile oils (such as apiol and myristicin) and flavonoids, which are thought to have mild diuretic properties. However, while animal studies have supported parsley’s diuretic effects, robust clinical trials in humans are lacking. The evidence base is therefore primarily traditional, with only limited scientific support. There is no strong evidence to suggest that parsley can prevent or treat serious kidney diseases. Moreover, excessive consumption of parsley, especially in medicinal doses, may not be safe for individuals with kidney disorders due to its high oxalate content and potential for exacerbating certain conditions.

In summary, parsley is traditionally used to support the kidneys, primarily through its mild diuretic action. While animal studies provide some mechanistic support, high-quality human trials are lacking, and caution is warranted for individuals with existing kidney issues.