Bilberry has a long medicinal history in Europe. It has been used to treat anything from kidney stones to Typhoid fever. During World War 2 British pilots noted that Bilberry jam before a flight dramatically improved night vision. Modern research now supports these claims. Bilberry contains anthocyanosides which are potent antioxidants which strengthen blood vessels and capillary walls, improve red blood cells, stabalize collagen tissues such as tendons, ligaments and cartilage and has cholesterol lowering effects. They also increase retinal pigments that allow the eye to tolerate light. In the past, dried bilberries have been used to treat diarrhea because the tannins it contains (1.5% and as much as 10%) act as an astringent to the gastrointestinal tract. An astringent shrinks and tightens the top layers of skin or mucous membranes thereby reducing secretions, relieving irritation, and improving tissue firmness. Tea brewed from dried bilberry fruits has also been used to soothe a sore throat or sore mouth tissue. In folk medicine, bilberry leaf has been used to treat a number of conditions including diabetes. Limited evidence from a few animal studies shows that it may have a decreasing effect on blood sugar. Additionally, in at least one study, an extract of bilberry leaves may also have lowered cholesterol levels in laboratory animals. Other laboratory and animal studies have tested potential anticancer effects of bilberry. In a laboratory study, bilberry stopped the growth of both leukemia and colon cancer cells. While preliminary results suggest that anthocyanosides obtained from bilberries may also block the effects of an enzyme and other chemicals that promote tumor growth, much more study is needed. To date, no human clinical studies have confirmed any of these results from bilberry. Recent research showed that Bilberry extract has promising anti-ulcer activity, both preventive and curative. It also has shown anti-cancer properties in animal experiments. When administered to diabetes patients, Bilberry normalised capillary collagen thickness and blood sugar levels in humans and animals.