Aescin, also known as escin, is a mixture of triterpene saponins found primarily in the seeds of the horse chestnut tree (Aesculus hippocastanum). Its use for supporting the veins, particularly in the context of chronic venous insufficiency (CVI) and varicose veins, is supported by a significant body of scientific evidence. Clinical trials and meta-analyses have shown that standardized horse chestnut seed extracts containing aescin can reduce symptoms such as leg pain, swelling (edema), and heaviness associated with CVI. The mechanism appears to involve reducing capillary permeability, improving venous tone, and exerting anti-inflammatory effects.

A 2012 Cochrane review and several randomized controlled trials have found that aescin is more effective than placebo and comparable to compression therapy for reducing leg volume and improving symptoms of venous insufficiency. The European Medicines Agency recognizes horse chestnut seed extract as a traditional herbal medicinal product for the relief of symptoms of discomfort and heaviness of legs related to minor venous circulatory disturbances. While aescin is generally well tolerated, mild gastrointestinal side effects have been reported in some studies.

In summary, the use of aescin for supporting the venous system is validated by modern clinical research, with an evidence rating of 4 out of 5, reflecting both efficacy and consistent study results, though more large-scale trials could further strengthen the evidence base.