What Is Bilberry Used for Today?
| What Is the Scientific Evidence for Bilberry?
| Safety Issues
| Interactions You Should Know About
Often called European blueberry, bilberry is closely related to American blueberry, cranberry, and huckleberry. The flesh of bilberry is red, and 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
, often dramatically. Subsequent investigation showed that bilberry contains biologically active substances known as anthocyanosides. Some evidence suggests that anthocyanosides may benefit the retina, as well as strengthen the walls of blood vessels, reduce inflammation, and stabilize tissues containing collagen (such as tendons, ligaments, and cartilage).
However, neither anecdote nor basic scientific evidence of this type can prove a treatment effective. Only
studies can do that. (For more information, see the article
Why Does This Database Rely on Double-blind Studies?
) Regarding night vision, the balance of the evidence suggests that bilberry is
helpful. Slight evidence hints that bilberry might be helpful for
. One double-blind study suggests that bilberry might be helpful for
Finally, because the anthocyanosides in bilberry resemble the oligomeric proanthocyanidin complexes (
) found in grape seed and pine bark, bilberry has been recommended for all the same uses as those substances, including
Animal studies also suggest that bilberry leaves (rather than the fruit) may be helpful for improving blood sugar control in
, and also in lowering blood
What Is the Scientific Evidence for Bilberry?
A double-blind crossover trial of 15 individuals found no short- or long-term improvements in night vision attributable to bilberry.
Similarly negative results were seen in a double-blind, placebo-controlled crossover trial of 18 subjects
and another of 16 subjects.
In contrast, two much earlier controlled, but not double-blind, studies of bilberry found that the herb temporarily improved night vision.
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.
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.
In a 4-week, double-blind, placebo-controlled study of 40 people with
, oral use of bilberry extract significantly reduced hemorrhoid symptoms as compared to placebo.
A double-blind, placebo-controlled trial of bilberry extract in 14 people with
or hypertensive retinopathy (damage to the retina caused by diabetes or
, respectively) found significant improvements in the treated group.
However, the small size of this study makes the results less than fully reliable. Other studies are also cited as indicating benefits, but they were not double-blind and therefore mean little.
Bilberry (whortleberry) fruit extract supplements were added to standard treatment for adults with
type 2 diabetes
resistant to diabetes medication and compared to placebo. Those who received the fruit extract had significant reductions in fasting blood glucose, glucose levels after eating, and HbA1c levels compared to regular treatment plus placebo.
The standard dosage of bilberry is 120 to 240 mg twice daily of an extract standardized to contain 25% anthocyanosides.
Bilberry fruit is a food and, as such, is quite safe. Enormous quantities have been administered to rats without toxic effects.
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.
Although safety in pregnancy has not been proven, clinical trials have enrolled pregnant women.
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.
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 people with diabetes could require a reduction in drug dosage.
Interactions You Should Know About