Anthocyanins are flavonoid compounds found in various fruits and vegetables, especially those with blue, purple, or red pigmentation (such as berries, grapes, and red cabbage). There is scientific evidence supporting their role in supporting capillary health and vascular integrity. Several studies have shown that anthocyanins possess antioxidant and anti-inflammatory properties, which can help protect capillary walls from oxidative stress and inflammation, factors that contribute to vascular fragility and permeability.

Clinical and preclinical research has observed that anthocyanins may improve microcirculation and decrease capillary permeability. For example, extracts from Vaccinium myrtillus (bilberry), which are rich in anthocyanins, have been traditionally used and studied for treatments related to capillary fragility, bruising, and microvascular disorders. Some randomized controlled trials have demonstrated improvements in vascular tone and reductions in symptoms such as edema and hemorrhages in patients with chronic venous insufficiency or diabetes-related microvascular complications.

However, while the evidence base is promising, it is not yet robust enough for the highest rating: many studies use anthocyanin-rich extracts rather than purified compounds, and larger, well-controlled trials are needed. Still, the mechanism (antioxidant protection, effects on endothelial cells) and clinical findings offer a moderate degree of scientific validation for using anthocyanins to support capillary health.