Rutosides (also known as rutin or rutoside) are flavonoid compounds found in various plants, including buckwheat, citrus fruits, and some medicinal herbs. Their use in supporting or treating capillary weakness is backed by a moderate amount of scientific evidence, particularly from clinical and pharmacological studies. Rutosides are known to strengthen capillaries by increasing their resistance and decreasing their permeability, which can help prevent or reduce capillary fragility and associated symptoms such as easy bruising, petechiae, or edema.

Several clinical trials and observational studies have explored rutosides for conditions characterized by capillary fragility, such as chronic venous insufficiency, hemorrhoids, and diabetic retinopathy. A systematic review (Int Angiol, 2017) found that rutosides can reduce symptoms like edema and improve capillary resistance in patients with chronic venous disorders. The mechanism is believed to involve antioxidative effects and stabilization of the vascular endothelium.

Although more large-scale, high-quality randomized controlled trials are needed, the available evidence supports the use of rutosides for improving capillary strength and vascular health. Rutosides are approved for these indications in various European countries, and their use is reflected in clinical guidelines for chronic venous insufficiency. However, the strength of evidence is not as robust as for some other pharmaceutical agents, hence the rating of 3/5.