Scotch Broom (Cytisus scoparius) has a long history of use in traditional European herbal medicine, particularly for supporting the cardiovascular system, including the capillaries. Historically, the aerial parts of the plant have been used in folk remedies to strengthen vascular walls, reduce capillary fragility, and support circulation. The primary active constituent is sparteine, an alkaloid thought to exert mild vasoconstrictive and cardiotonic effects, potentially influencing vascular tone and capillary health. However, most of the evidence for these uses comes from historical texts and ethnobotanical sources rather than rigorous clinical trials.

There is limited preclinical research suggesting that Scotch Broom may have effects on blood vessels, but comprehensive human studies are lacking. The herb has been largely replaced by more researched and safer alternatives in modern herbal practice due to concerns about toxicity and the narrow therapeutic window of its alkaloids. The use of Scotch Broom for supporting the capillaries is thus grounded primarily in tradition with only modest supporting data from laboratory studies, and it is not widely recommended today. Caution is advised due to potential side effects and lack of robust clinical evidence.