Herbs & Supplements:
Bilberry - ( Vaccinium myrtillus )
Principal Proposed Uses
•
Eye Problems, Poor Night Vision, Diabetic Retinopathy, Prevention of Cataracts, Prevention and Treatment of Macular Degeneration, Strengthen Blood Vessels, Easy Bruising, Prevention of Post-Surgical Bleeding
Other Proposed Uses
•
Atherosclerosis, Diabetes (Leaf Rather Than Fruit)
Often called European blueberry, bilberry is closely related to American blueberry, cranberry, and huckleberry. Its meat is creamy white instead of purple, but it is traditionally used, like blueberries, in the preparation of jams, pies, cobblers, and cakes.
Bilberry fruit also has a long medicinal history. In the twelfth century, Abbess Hildegard of Bingen wrote of bilberry's usefulness for inducing menstruation. Over subsequent centuries, the list of uses for bilberry grew to include a bewildering variety of possibilities, from bladder stones to typhoid fever.
What Is Bilberry Used for Today?
The modern use of bilberry dates back to World War II, when British Royal Air Force pilots reported that a good dose of bilberry jam just prior to a mission improved their night vision, often dramatically. After the war, medical researchers investigated the constituents of bilberry and subsequently recommended it for a variety of eye disorders.
Bilberry is used throughout Europe today for the treatment of poor night vision and day blindness, for which it is believed to be significantly helpful. However, the scientific evidence that it works is more negative than positive, with the most recent studies finding no benefit.
Regular use of bilberry is also sometimes used in hopes that it can prevent or treat other eye diseases such as macular degeneration, diabetic retinopathy, and cataracts. However, there is no solid evidence that it works for any of these conditions.
Scientific research also found that bilberry contains biologically powerful substances known as anthocyanosides. Evidence suggests that anthocyanosides strengthen the walls of blood vessels, reduce inflammation, and generally stabilize all tissues containing collagen (such as tendons, ligaments, and cartilage).1–5 Bilberry's anthocyanosides in particular have been found to interact with the eye.6,7 European physicians believe that bilberry's blood vessel–stabilizing properties also make it useful as a treatment before surgery to reduce bleeding complications, as well as for other blood-vessel problems such as easy bruising, but the evidence as yet is only suggestive.
Animal studies also suggest that bilberry leaves (rather than the fruit) may be helpful for improving blood sugar control in diabetes, and also in lowering blood triglycerides.8
What Is the Scientific Evidence for Bilberry?
Night Vision
A double-blind crossover trial of 15 individuals found no short- or long-term improvements in night vision attributable to bilberry.9 Similarly negative results were seen in a double-blind placebo-controlled crossover trial of 18 subjects10 and another of 16 subjects.11
In contrast, two much earlier controlled, but not double-blind, studies of bilberry found that the herb temporarily improved night vision.12,13 However, the effect was not found to persist with continued use. A later double-blind placebo-controlled study on 40 healthy subjects found that a single dose of bilberry extract improved visual response for 2 hours.14
Visual benefits have also been reported in other small trials, but these studies did not use a placebo control group and are therefore not valid as evidence.15,16,17
Diabetic Retinopathy
A double-blind placebo-controlled trial of bilberry extract in 14 people with damage to the retina caused by diabetes and/or hypertension found significant improvements observable by ophthalmoscopic examination (looking in the eye with a machine) and angiography (examining the blood vessels).18 However, this was a very preliminary study.
Other studies have found similar results, but they were not double-blind.19,20
Dosage
The standard dosage of bilberry is 120 to 240 mg twice daily of an extract standardized to contain 25% anthocyanosides.
Safety Issues
Bilberry fruit is a food and as such is quite safe. Enormous quantities have been administered to rats without toxic effects.21,22 One study of 2,295 people given bilberry extract found a 4% incidence of side effects such as mild digestive distress, skin rashes, and drowsiness.23 Although safety in pregnancy has not been proven, clinical trials have enrolled pregnant women.24 Safety in young children, nursing women, or those with severe liver or kidney disease is not known.There are no known drug interactions. Bilberry does not appear to interfere with blood clotting.25
Little is known about the safety of bilberry leaf. Based on animal evidence that it can reduce blood sugar levels in people with diabetes, it is possible that use of bilberry leaf by diabetics could require a reduction in drug dosage.26
Interactions You Should Know About
If you are taking medications to reduce blood sugar, bilberry leaf (not fruit) might amplify the effect, and you may need to reduce your dose of medication.
View References
Last reviewed March 2002 by Medical Review Board
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