Introduction
A type of blueberry, bilberry is a small deciduous shrub found in barren fields and underbrush mainly throughout central and northern Europe.¹ Bilberry has bright green leaves, and it produces greenish-pink, bell-shaped flowers in late spring and early summer, followed by bluish-black, round fruits.² The bilberry fruits and leaves of commerce are wild collected in European countries, in particular in Bosnia and Herzegovina, Bulgaria, Croatia, Romania,³ Macedonia,⁴ Serbia and Montenegro,⁵ and Kosovo,⁶ with significant amounts increasingly being wild collected under organic certification mainly in the Russian Federation, Bulgaria, Romania, Sweden, Poland, Ukraine, and Finland.⁷

History and Cultural Significance
The name bilberry is derived from the Danish word bollebar, meaning dark berry.⁸ The species name myrtillus refers to the resemblance of the leaves to those of myrtle (Myrtus communis, Myrtaceae). Common names for bilberry in England include bleaberry, blueberry, and common whortleberry.⁹

Bilberry fruit has been used in traditional European medicine for nearly one thousand years.¹⁰ Long consumed as a traditional food, the use of bilberry fruits as an herbal medicine emerged in the Middle Ages and was mentioned by Saint Hildegard of Bingen (1098-1179), the medieval abbess who discussed extensively the medicinal properties of plants in her writings. The 16^th century German herbalist Hieronymos Bock recommended the berries for treatment of bladder stones, liver disorders, and in syrups for coughs and lung ailments. In the 18^th century, the use of bilberry fruits became widespread among herbalists and physicians, particularly in Germany, for intestinal conditions; typhoid fever; mouth, skin, and urinary tract infections; gout; and rheumatism. By the early 20^th century, dried bilberry tea was used as an astringent for diarrhea and dysentery, as a diuretic, cooling nutritive tonic, and to stop bleeding.⁹

Strong decoctions (e.g., teas made by steeping 1 to 2 tablespoonfuls of dried fruit in about 150 ml of boiling water for at least 10 minutes)¹¹ of dried bilberry fruit have been drunk traditionally to treat diarrhea. Bilberry preparations were also used historically to relieve scurvy (a disease caused by Vitamin C deficiency) and painful urination, and to help stop the flow of breast milk.⁸

In 1987, the German Commission E approved the internal use of bilberry fruit (prepared as a decoction or equivalent preparation) to treat non-specific, acute diarrhea, and the 10% decoction for local (topical) use for mild inflammation of the mucous membranes of the mouth and throat.¹² Elsewhere in Europe, particularly in Italy, concentrated bilberry fruit preparations are used for circulatory support.^1,13 In 2008, Health Canada published its final monograph for bilberry natural health product (NHP) compendial license applications. Health Canada approved the traditional medicinal oral use of bilberry as an astringent to help relieve diarrhea and the gargle and/or buccal (of the cheeks or mouth cavity) use of the 10% decoction of the dried fruit to help relieve mild inflammations of the mucous membranes of the mouth and/or throat.¹⁴

European pharmacopeial-quality fresh bilberry fruit is the fresh or frozen, ripe fruit of Vaccinium myrtillus containing minimum 0.30% of anthocyanins, expressed as cyanidin-3-O-glucoside chloride. Pharmacopeial-quality dried bilberry fruit is the dried ripe fruit containing minimum 1.0% of tannins, expressed as pyrogallol. Both the dried and fresh fruit should have a sweet and slightly astringent taste. In 2008, an official quality standards monograph for the refined and standardized dry extract of fresh bilberry fruit was added to the European Pharmacopoeia.¹⁵ Also in 2008, the United States Pharmacopeia published its quality standards monograph for Powdered Bilberry Extract, prepared from the ripe fruits of V. myrtillus using suitable solvents such as alcohol, methanol, or water, or mixtures of these solvents. The ratio of the starting plant material to Powdered Extract is between 153:1 and 76:1. It must contain minimum 36.0% of anthocyanosides, calculated as cyanidin-3O-glucoside chloride, and maximum 1.0% of anthocyanidins, calculated as cyanidin chloride.¹⁶

The primary application of anthocyanoside-enriched bilberry extracts in ophthalmology focuses on diabetic retinopathy, where bilberry can be used as an adjuvant in combination with conventional pharmaceutical therapies. Bilberry extract improves capillary fragility, reducing vessel proliferation through an anti-angiogenetic mechanism related to the high content of delphinidin. This appears to be a unique property of bilberry compared to most other anthocyanoside-containing, fruit-derived extracts. In diabetic patients bilberry extract improves cicatrisation (healing of a wound by producing scar tissue) of leg ulcers, combining a proteases inhibitory effect with anti-edema (anti-inflammatory) properties.

A recent uncontrolled trial found that a standardized bilberry extract (Mirtoselect®, Indena, Milan, Italy) combined with a patented French maritime pine bark extract (Pycnogenol®, Horphag Research, Geneva, Switzerland) called Mirtogenol® was able to lower ocular pressure in non-glaucoma patients with ocular hypertension.¹⁸ Additional clinical trials have documented the benefits of bilberry extracts in treating venous insufficiency.¹³ The concentrated extract also has been evaluated for its possible effects in treating inflamed oral and pharyngeal membranes¹² as well as on painful menstruation.¹⁹

Owing to the relatively high commercial value of bilberry extracts, intentional adulteration has been detected, not only with anthocyanosides obtained from other plant sources, but even with synthetic dyes, e.g., amaranth dye, a synthetic dye used in foods (not related to what is often called “grain amaranth” [Amaranthus spp., Amaranthaceae], the increasingly popular food cultivated and marketed for its relatively high protein content.) Analytical methods have been developed to determine such adulteration for use by responsible manufacturers.²²