... America, Europe, and northern Asia. What It Is Used For:Historically, bilberry fruit was used to treat diarrhea, scurvy, ... Today, the fruit is used to treat diarrhea, menstrual cramps, eye problems, varicose veins, venous insufficiency (a condition in which ... the legs to the heart), and other circulatory problems.·Bilberry leaf is used for entirely different conditions, including diabetes. How It ...