Alisma (Alisma orientale), also known as water plantain, has a long history of use in traditional Chinese medicine (TCM) for supporting the urinary system. In TCM, Alisma is known as "Ze Xie" and is frequently included in herbal formulas to promote urination, drain dampness, and address symptoms such as edema, dysuria (painful urination), and urinary tract discomfort. The traditional rationale is rooted in the herb's diuretic properties, believed to help balance water metabolism and eliminate "damp" conditions in the body.

Scientific studies on Alisma are limited and not robust. Some animal and in vitro research suggests potential diuretic and anti-inflammatory effects, but these studies are preliminary and not sufficient to constitute strong scientific validation. Clinical trials in humans are sparse and often of low methodological quality. Thus, while some pharmacological actions have been observed in laboratory settings, the evidence is not strong enough to claim scientifically validated support for urinary health in humans.

In summary, Alisma's use to support the urinary system is primarily justified by traditional practice rather than solid scientific evidence. Its long-standing role in TCM underpins its reputation, but more rigorous clinical studies are needed to substantiate its efficacy and safety for this purpose.