Bilberry Fruit Extract for Night Vision
February 1999; Volume 2: 20-21
By Ernie-Paul Barrette, MD
Bilberry has carved a unique niche in the market with its availability for healthy vision. In the United States, more than $4.5 million was spent in 1997 on this herbal supplement, ranking it number 11. In Germany’s robust market for herbal supplements, however, bilberry does not make the top 20.1 How should you respond when a patient tells you they have started bilberry for their vision?
The fruit of the dwarf shrub Vaccinium myrtillus, bilberries or whortleberries, are found in northern and central Europe and in the Rocky Mountains of the United States. The name bilberry is derived from the Danish, "bollebar," meaning dark fruit. It is related to the North American huckleberry. The berries were used in jams and for coloring wine. In England during World War I, bilberries were substituted for aniline dyes, which were no longer available from Germany.
Traditionally a tea made of the dried fruit has been used for diarrhea and topically as a decoction for inflammation of the mouth and throat.2 A widely repeated anecdote links bilberries to vision. During World War II, British Royal Air Force pilots flying night missions reportedly performed better after ingesting bilberry preserves. This led to the belief that bilberry improves night vision.
The active component of bilberry is likely a bioflavonoid. Experiments have used bilberry extracts that have concentrated the anthocyanosides of the fruit. These extracts are a complex mixture, and contain minimally 15 anthocyanosides: 5 anthocyanidins (delphinidin, cyanidin, petunidin, peonidin, malvidin) bonded to one of three carbohydrates (glucose, galactose, arabinose). The fresh fruit contains 0.1-0.25% of anthocyanosides along with sugars, tannins, and pectin.
Mechanisms of Action
In animal models, anthocyanosides appear to stabilize collagen,3 decrease capillary permeability due to injury,4 and protect against ischemia reperfusion injury.5 The generalizability of these experiments is limited by the investigators’ use of extremely high doses of drug (e.g., 100-400 mg/kg). Anthocyanosides may increase visual pigment regeneration. Vaccinium myrtillus extract protects human LDL against oxidative injury in an in vitro system, presumably by scavenging free radicals.6
In a non-randomized, controlled study, 37 subjects with normal vision received either bilberry fruit extract (Vaccinium myrtillus extract) or placebo. Several tests measuring different aspects of vision at low levels of light were improved four hours after a single dose of bilberry extract. However, after one week of twice-daily bilberry extract, the results were no longer statistically significant.7
A second controlled study of night vision included 60 normal subjects who received either a single 600 mg dose of Vaccinium myrtillus extract or placebo. Testing one and two hours later noted a statistically significant improvement in those receiving Vaccinium myrtillus extract compared to placebo, though the clinical difference was described as "slight."8
Studies in patients with ophthalmologic disorders are difficult to interpret. Fourteen patients with significant hemeralopia (diminished vision in bright light) were treated with Vaccinium myrtillus extract without controls. Vision improved during treatment and returned to baseline after discontinuation.9
In an often-quoted study, 22 patients (myopia 8, glaucoma 8, retinitis pigmentosa 6) were studied before and 90 minutes after a single PO 200 mg dose of Vaccinium myrtillus extract. The patients with myopia and glaucoma showed improvement compared to baseline. Eight patients with diabetic retinopathy and six with hypertensive retinopathy were treated with 250 mg Vaccinium myrtillus extract daily for one month without controls. Retinal angiograms were unchanged.10
A case series of 20 patients with diabetic retinopathy were treated with 400 mg bid Vaccinium myrtillus extract and 20 mg of beta-carotene. Follow-up data were available for 12 subjects and showed increases in the conjunctival capillary resistance. The authors postulate this will provide long-term protection against retinal hemorrhage.11
Another widely quoted report supporting the use of bilberry fruit extract studied 31 patients with various retinopathies. Retinal examinations were performed at baseline and after one month of 200 mg Vaccinium myrtillus extract/10 mg beta-carotene three times daily without controls. Thirteen of the 20 subjects with diabetic retinopathy improved after treatment and then worsened one month after discontinuation of the drug.12
In an open-label, one-year study of 78 patients with macular degeneration, diabetic retinopathy, retinal inflammation, or retinitis pigmentosa, 19 of 37 patients treated daily with 400 mg Vaccinium myrtillus extract/20 mg beta-carotene enjoyed improved vision. The remaining 41 patients received either 200 mg Vaccinium myrtillus extract/200 mg vitamin E or only 200 mg vitamin E. Improvement was seen in 11 of 21 vs. two of 20 respectively (no statistics reported).13
The same author has reported a case series of nine patients on chronic anticoagulation complicated by retinal hemorrhage who were successfully treated with Vaccinium myrtillus extract/beta-carotene without interruption of the anticoagulant.14
Adverse effects have not been reported with extracts of the fruit. Very high doses have not resulted in toxic effects in animals. However, chronic ingestion or higher doses of bilberry leaf in animals has resulted in cachexia, anemia, icterus, excitation, and death.
No significant drug interactions with bilberry fruit extract have been reported. Vaccinium myrtillus extract did not affect coagulation parameters in one study.12
Bilberry fruit extract is usually sold as 80 mg capsules standardized to contain 25% anthocyanosides. It is listed in the French, Swiss, and Austrian pharmacopoeias. In Europe many proprietary formulations are available, e.g., Difrarel. Generally, 80 to 160 mg three times daily is recommended.15
Bilberry fruit extract is marketed to promote healthy vision. This claim is not supported by the German Commission E Monographs. The studies in various ophthalmologic disorders are limited by lack of controls and blinding, short duration, small sample sizes, and mixing of various disorders. In addition, most of the European studies used proprietary combination products unavail- able in the United States. The therapeutic equivalence with available U.S. formulations should not be assumed.
The published evidence suggest that Vaccinium myrtillus extract may briefly improve night vision, but self-medication may delay accurate diagnosis and long-lasting treatment. Routine use of bilberry fruit extract for ocular symptoms or diseases should not be supported. Since many effective interventions exist for most vision disorders, full ophthalmologic evaluation for any significant symptom is appropriate.
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14. Neumann L. Erfahrungen mit Anthocyanosidbehandlung von Netzhautblutungen unter Antikoagulantien Dauertherapie. Klin Monatsbl Augenheilkd 1973:163;96-103.
15. Pizzorno JE, Murray MT. A Textbook of Natural Medicine. Seattle, WA: Bastyr University Publications; 1992.