Plantago (most commonly Plantago major or Plantago lanceolata), also known as plantain, has a long history of use in traditional herbal medicine for a variety of ailments, including wound healing and as an anti-inflammatory agent. The use of Plantago to support or treat capillary weakness is primarily grounded in traditional herbal practices, particularly in European phytotherapy. Historically, Plantago leaves have been used topically and internally to promote tissue repair, reduce bleeding, and support blood vessel integrity, which may indirectly suggest a role in addressing capillary fragility.

Traditional texts and herbalists have often cited Plantago's astringent and anti-inflammatory properties, believed to help "strengthen" blood vessels and reduce minor bleeding or bruising. However, the evidence base remains limited to anecdotal and historical records, with only a few modern studies investigating Plantago's effects on vascular health specifically. Some phytochemical analyses reveal the presence of bioactive compounds such as flavonoids, tannins, and allantoin, which could theoretically confer some protective effects on blood vessels, but direct clinical evidence supporting its use for capillary weakness is lacking.

In summary, Plantago's use for capillary weakness is supported mainly by tradition rather than robust scientific research. While certain constituents in Plantago may have vasoprotective potential, there is insufficient clinical data to conclusively validate its effectiveness for this specific indication.