Bilberry

Vaccinium myrtillus

Common Names

• Huckleberry

• European blueberry

• Whortleberry

• Blueberry

General Description

Bilberry is a shrubby perennial plant that grows in wooded areas of the northern US and forest meadows of Europe.  Plants may grow up to 1.5 feet, producing 0.5 to 1.0-inch long leaves which are oval and bright green.  The flowers however are reddish- or greenish-pink and bell-shaped.  The fruit itself is blue-black or purple, and the meat of the fruit is also purple.

Chemical Composition

Anthocyanosides are the pharmacologically active constituents of bilberries.  These molecules consist of a backbone known as anthocyanidin which is bound to one of three sugars:  arabinose, glucose, or galactose.  Five different anthocyanidins in bilberry produce more than fifteen different anthocyanosides.  The fresh fruit contains an anthocyanoside concentration of 0.1 to 0.25 percent.  A concentrated bilberry extract however yields 25% anthocyanidin content, which corresponds to about 38% anthocyanosides.  Anthocyanoside content should always be expressed in terms of anthocyanidin.

Bilberry also contains vitamin A, vitamin C, catechol tannins, and hydroquinone.

History and Folk Use

Besides as food, bilberries have been used for the treatment of scurvy and urinary tract infections and stones.  Because of their asringent properties, the dried berries have been used to treat diarrhea and dysentery.  Decoctions of the leaves have been used in diabetes treatment.

During World War II, the British Royal Air Force noted reports from pilots that nighttime visual acuity was improved after consuming bilberries.  Subsequent studies showed that bilberry improved nighttime visual acuity,  provided quicker adjustment to darkness and faster restoration of visual acuity after exposure to glare.  Currently, European medicine uses bilberry extracts to treat several ocular disorders such as cataracts, macular degeneration, retinitis pigmentosa, diabetic retinopathy, and night blindness.

Pharmacology

The pharmacology of bilberry is related to its anthocyanoside content.

Collagen-stabilizing action

• Anthocyanosides can actually cross-link collagen fibers.  This reinforces the collagen matrix of connective tissue (cartilage, tendons, etc.)

• Damage by free radicals can be prevented by anthocyanosides, which are potent antioxidants and free radical scavengers.

• During inflammation, leukocytes secrete cyzymes which cleave collagen.  Anthocyanosides inhibit this cleavage.

• Anthocyanosides can prevent the release of histamine, serine proteases, prostaglandins, and leukotrienes, all of which are mobilized during an inflammatory process.

• Anthocyanosides also promote mucopolysaccharide and collagen biosynthesis and stimulate reticulation of collagen fibrils.

Normalization of capillary permeability

• Anthocyanosides increase intracellular vitamin C levels and reduce the permeability and fragility of capillaries.  One example of this is a decreased permeability of the blood-brain barrier.  Certain autoimmune diseases of the CNS, schizophrenia, and other psychiatric disorders have been linked to an increased permability of the blood-brain barrier.  Anthocyanosides may maintain and restore the brain's protection from drugs, pollutants, degradory products, and other toxins by inhibiting the enzymatic and nonenzymatic degradtion of the basement membrane collagen of the brain's capillaries.

Antiaggregation effect on platelets

• By reducing excessive platelet aggregation, anthocyanosides can prevent atherosclerosis and formation of thrombi.

Hypoglycemic effect

• Myrtillin is the most active hypoglycemic component of bilberry, and on injection is weaker than insulin, but less toxic even at 50 times the therapeutic dose (1 gram/day).  A single dose can produce beneficial effects that persist for several weeks.

Smooth muscle-relaxing activity

A preliminary study using anthocyanosides in the treatment of dysmenorrhea has demonstrated positive effects (Colombo and Vescovini).

Antiulcer effects

In rat models, oral administration of bilberry anthocyanosides showed both preventative and curative antiulcer activity.  Gastric secretion was unaffected.  The activity is attributed to an increase in gastric mucus.

Clinical Applications

Bilberry extracts are used extensively in Europe for ocular conditions, vascular disorders, peptic ulcers, prevention of diabetic retinopathy, and dysmenorrhea.

Ocular Disorders

Presumably by increasing delivery of oxygen and blood to the eye, as well as scavenging free radicals, bilberry extracts can offer benefit in ocular disorders such as cataracts and macular degeneration.  By increasing the integrity of collagen structures in the eye, bilberry may help prevent and treat glaucoma.

Research suggests that purple bilberry anthocyanosides have an affinity for the pigmented epithelium, or visual purple, area of the retina.  This area plays a key role in vision and is also in control of the adaptation from dark to light (and vice versa).  The result is that bilberry can be very beneficial in the treatment of both poor night and poor day vision.

Bilberry may offer some protective benefits against cataracts and macular degeneration.  In addition, bilberry anthocyanosides exert a protective effect on capillary fragility in diabetics, perhaps preventing the onset of diabetic retinopathy.

Varicose Veins

Anthocyanosides protect postphlebitic and varicose veins by 1) stabilizing membrane phospholipids, resulting in an increase in the endothelium barrier, and 2)  restoring venous surrounding tissue by increasing biosynthesis of the connective ground substance.

Dosage

Bilberry doses should be based on anthocyanoside content:

• Anthocyanosides (caldulated as anthocyanidin):  20-40 mg

• Bilberry extract (25% anthocyanidin content):  80-160 mg

Toxicity

Bilberry appears to have very low toxicity.  In one study, rats were given doses as high as 400 mg/kg.  The rats showed no apparent side effects, and excess levels were rapidly excreted via biliary and renal elimination.  The German Commission E however states that higher doses or prolonged use of bilberry may cause intoxication, anemia, acute excitatory states, and even death (at doses of 1.5 g/kg/day).

References

Bisset N (ed).  Herbal Drugs and Phytopharmaceuticals:  A Handbook for Practice on a Scientific Basis.  Boca Raton, FL:  CRC Pres, 1994, pp. 348-352.

Brill S.  Identifying and Harvesting Edible and Medicinal Plants in Wild (and Not so Wild) Places.  New York:  Hearst Books, 1994, pp. 98-100.

Detre Z, et al.  "Studies on Vascular Permeability in Hypertension:  Action of Anthocyanodises."  Clinical Physiology Biochemistry, Vol. 4, 1986, pp. 143-149.

Jones, Andrea and Arlen Rash.  "Bilberry:  Vaccinium Myrtillus."  Presentation Handout, Pharmacy 100, Fall 1998, University of North Carolina School of Pharmacy.

Monboisse J.  "Oxygen-Free Radicals as Mediators of Collagen Breakage."  Agents and Actions, Vol. 15, No. 1/2, 1984, pp. 49-50.

Moore M.  Medicinal Plants of the Pacific West.  Santa Fe, New Mexico:  Red Crane Books, 1993, pp. 82-87.

Murray M.  The Healing Power of Herbs.  Rocklin, CA:  Prima Publishing, 1996, pp. 50-59.

Murray M and Joseph Pizzorno.  Encyclopedia of Natural Medicine.  Rocklin, CA:  Prima Publishing, 1998.

Pizzorno J and M Murray.  A Textbook of Natural Medicine:  Vaccinium Myrtillus.  Bothell, WA:  Bastyr University Publications, Vol. 1, 1996.

Web sites as follows:

http://www.smartbasic.com/glos.herbs/bilberry.html

http://www.botanical.com/botanical/mgmh/b/bilber37.html

http://www.hsv.tis.net/dymedias/a/accm/BILBERRY.HTM