Bilberry Leaf

SCIENTIFIC NAME : Vaccinium Myrtillus, Myrtilli fructus

COMMON NAME : Bilberries, Bog Bilberries,

BOTANY

Bilberry fruit originates from Northern and Central Europe and has been imported from parts of south-eastern Europe. These black, coarsely wrinkled berries contain many small, shiny brownish-red seeds. They have a somewhat caustic and sweet taste.

HISTORY

The historical uses of dried bilberry fruit include being a supportive treatment of acute, non-specific diarrhea when administered as a tea and serving as a topical decoction for the inflammation of the mucous membranes of the mouth and throat.

During World War II, British Royal Air Force pilots ate bilberry preserves before night missions in order to im­prove their vision. After the war, studies confirmed the folk beliefs that bilberry extracts could improve visual acuity and lead to faster visual adjustments between light (eg, glare) and darkness. Some European physicians went on to recommend bilberry extracts for other eye com­plaints (eg, retinitis pigmentosa, diabetic retinopathy). Clinical studies, however, have not confirmed these therapeutic applications.

CHEMISTRY

According to older studies, bilberry con­sists of up to 10% tannins, most of which are catechol tannins. However, recent studies suggest that tannins constitute only 1.5%. In addition to tannins, bilberry contains anthocyans, flavonoids, plant acids, invert sug­ars and pectins. The fresh fruit does not have the antidi­arrhetic effects; therefore, it must be dried to obtain the tannins which come about by the condensation of the monomeric tannin precursors during the drying process.

PHARMACOLOGY

Dried bilberry fruit is used as an antidiarrhetic drug, especially in mild cases of enteritis. It is also used as a topical treatment for mild inflammation of the mucous membranes of the mouth and throat.

Most clinical studies have concentrated on the fruit's anthocyanoside content. An experiment using a prepara­lion of anthocyanosides from bilberry (equal to 25% of anthocyanidins) indicated vasoprotective and anti edema effects in experimental animals. Oral doses of 25-100 mg/kg increased the permeability of the skin capillary. Antiedema activity was discovered after intravenous or lopical use.

When vascular permeability is increased in rabbits by cholesterol-induced atheroma, a treatment of anthocy­anosides from bilberry decreases vascular permeability. This is acheived when the drug interacts with collagen to increase its cross-links. The administration of anthocy­anosides before the induction of hypertension in rats maintains normal blood-barrier permeability and limits the increase in vascular permeability. This may also result from the interaction of the drug with collagens of the blood vessel walls to protect against the permeability-increasing action of hypertension.

Vaccinium myrtillus anthocyanosides are effective in pro­moting and intensifying arteriolar rhythmic diameter changes which aid in the redistribution of microvascular blood flow and interstitial fluid formation.

An investigation using an anthocyanidin pigment (ldB 1027) found in bilberries showed protective gastric effects without influencing acid secretion. The pigment was admin­istered orally using 600 mg b.Ld. for 10 days in 10 laboratory animals. The results showed an inccease in the gastric mucosal release of prostaglandin E2 which may explain the antiulcer and gastroprotective effects of Anthocyans and vitamin E are natural antioxidants which produce a protective effect on liver cells damaged by injury.

TOXICOLOGY

The effects of ingesting large doses of bilberry are not known. There are no known side effects or interactions with other drugs.

It is important that the fruit has not been attacked by insects and that it is free of mold. The berries should be as soft as possible or the long-stored drug will become hard and brittle.

SUMMARY

The bilberry fruit is administered as a tea to treat acute, non-specific diarrhea. It may also be used topically for mild inflammation of the mucous membranes of the mouth and throat. Studies have shown various possible effects such as vasoprotectivity, antiedemic ef­fects, decreasing vascular permeability, gastroprotectiv­ity, hepatoprotectivity and intensifying arteriolar rhythmic diameter. However, further studies are need to prove these effects.