Mexican Sarsaparilla (Smilax spp.) has a long history of use in traditional herbal medicine, particularly in Central and South America. In these systems, it has been used as a tonic for the kidneys, believed to help "cleanse" or "purify" the blood and support urinary tract health. The traditional rationale is largely based on its diuretic properties, which may promote increased urine flow and thereby, theoretically, assist the kidneys in flushing out waste products.

However, there is little to no robust scientific evidence directly supporting its efficacy for kidney health in humans. Most of the available research on sarsaparilla focuses on its potential anti-inflammatory, antimicrobial, and anti-arthritic properties, rather than its effects on kidney function. Furthermore, the diuretic effect has not been well quantified in clinical studies. The use of sarsaparilla for kidney support remains primarily a traditional practice, with evidence based on historical use and anecdotal reports rather than validated scientific findings.

In summary, while Mexican Sarsaparilla is traditionally used to support the kidneys, the evidence for its effectiveness is weak, and there are no rigorous clinical trials to substantiate its use for this purpose.