Anthocyanosides, the flavonoid complex in bilberries, speed the regeneration of rhodopsin, the purple pigment that is used by the rods in the eye for night vision.² While earlier trials suggested that taking bilberry could benefit people with night blindness,^{3, 4} more recent trials with healthy volunteers have found no effect of bilberry on night vision.^{5, 6} Preliminary human trials conducted in Europe show that bilberry may prevent cataracts,⁷ and may even help to treat people with mild retinopathies (such as macular degeneration and diabetic retinopathy).^{8, 9} Anthocyanosides are potent antioxidants.¹⁰ They support normal formation of connective tissue and strengthen capillaries in the body. Anthocyanosides may also improve capillary and venous blood flow. Bilberry may also prevent blood vessel thickening due to diabetes.¹¹

Bilberry protects cholesterol from oxidizing in test tubes.¹² While this action is thought to help prevent atherosclerosis, no human trials have studied whether bilberry may be useful in the regard.