Tall Buckwheat (Eriogonum elongatum or sometimes referencing the more commonly researched Fagopyrum esculentum, or common buckwheat) has a traditional reputation for supporting capillary health, primarily due to its content of the flavonoid rutin. Rutin is known for its ability to strengthen capillaries and reduce their fragility, which historically led to the use of buckwheat-based herbal remedies for conditions like varicose veins and easy bruising. Most of the traditional evidence comes from European and Asian herbal medicine, where preparations of buckwheat have been used for circulatory support, especially where capillary health is concerned.

Scientifically, the majority of supportive evidence relates not specifically to "Tall Buckwheat" but to rutin itself, which is present in various buckwheat species. Some clinical studies suggest rutin can help reduce capillary permeability and fragility, but robust, high-quality clinical trials specifically on Tall Buckwheat are lacking. Most modern usage and supplement formulations reference the general buckwheat plant or isolated rutin, rather than Tall Buckwheat per se.

In summary, the use of Tall Buckwheat for capillary support is primarily justified by traditional herbal practices, with scientific interest focusing on its rutin content; however, direct scientific validation for Tall Buckwheat itself remains limited.