Bilberry (Vaccinium Myrtilus)

James Meschino DC, MS, ROHP

General Features

Bilberry extract is well recognized for its ability to support collagen tissue (especially in blood vessel supporting connective tissues) and provides antioxidant protection to the macula of the eye.  As such, it is recommended for certain eye conditions, such as macular degeneration, diabetic retinopathy, and in cases of capillary fragility.  During World War II British fighter pilots taking Bilberry  reported an improved ability to adjust to glare and an increase in their visual acuity and nighttime vision.^21,22,23

Active Ingredients

Research has focused primarily upon the anthocyanosides, which are flavonoid compounds, unique to Bilberry  extract.  They are formed by an anthocyanidin backbone bound to one of three sugars (arabinose, glucose or galactose).

The concentration of anthocyanosides in the fresh fruit is only 0.1 to 0.25 percent, whereas concentrated extracts of Bilberry  taken as supplements yield an anthocyanidin content of 25 percent.^1,2,3,21,22

Mechanism of Action

1. Collagen

Stabilizing action – Bilberry  preserves collagen and related ground substance by increasing the cross-linking of collagen fibers, acting as a free radical scavenger, inhibiting enzymatic cleavage of collagen by enzymes secreted by leukocytes during inflammation, reducing the release of histamine, serine proteases, prostaglandins and leukotrienes and by promoting the  synthesis of glycosaminoglycans (see glucosamine in this document) and collagen by chondrocytes.^4,5,6,7

2. Anti-aggregation of platelets

Like many other flavonoids anthocyanosides heve been shown to decrease platelet aggregation in experimental studies.^8,9,10

3. Antioxidant

The anthocyanodins derived form Bilberry  also demonstrate very potent antioxidant properties.⁴

Clinical Applications

1. Macular Degeneration of the Eye

Macular degeneration is the most common cause of blindness in individuals over the age of 55 (see also Lutein and Zeaxanthin in this document) in North America. Bilberry  anthocyanidins appear to be able to help defend against and manage macular degeneration and other eye conditions via several biological actions.  The first is that these unique flavonoids have been shown to improve the delivery of oxygen and blood to the eye.  The second is that they provide antioxidant protection against ultra-violet light induced free radical damage (from sunlight) to the macula of the eye, which has been shown to contribute to the development and progression of macular degeneration.  Third, anthocyanidins from Bilberry  have been shown to stabilize the blood vessel wall of small blood vessels in the macular region of the eye, helping to prevent leaking of blood (micro-hemorrhaging) into the macular region as often occurs in diabetic retinopathy and the wet form of macular degeneration.  Like the antioxidant carotenoids lutein and zeaxanthin, Bilberry  anthocyanosides are known to concentrate in the macula of the eye, where they have the opportunity to quench ultra-violet light induced free radicals.^21,22

In one study, 31 patients with various retinopathies (20 diabetic, 5 retinitis pigmentosa, 4 macular degeneration, 2 hemorrhagic retinopathy) were treated with Bilberry  extract.

There was a tendency toward reduced permeability and hemorrhage observed in all patients, especially in those with diabetic retinopathy.¹⁸

2. Cataract

In the study by Bravetti G. (1989), Bilberry  extract, plus vitamin E stopped progression of cataract formation in 97 percent of 50 patients with senile cortical cataracts.  This effect is thought to be due to its powerful antioxidant properties, protecting the lens of the eye from oxidation and regenerating its collagen fibers.¹⁷

3. Night Vision

Bilberry  anthocyanosides have an affinity for the pigmented epithelium or visual purple of the retina, which is the portion of the retina responsible for night vision (rhodopson pigment formed from vitamin A on the rods).

The Royal Air Force pilots reported improved night vision during World War II with the use of Bilberry  extract (also, quicker adjustment to darkness and faster recovery from glare).  Even individuals with retinitis pigmentosa and hemeralopia (day blindness) have realized impressive improvement with Bilberry  extract supplementation.^{11,12,13,14,15,16,17,18}

 Varicose Veins and Capillary Fragility

Via its effects on collagen and connective tissues, which include increased synthesis of glycosaminoglycans (cement substance between fibers), reduced permeability and impaired prostaglandin synthesis, Bilberry  has been used in clinical trials with capillary fragility problems.  In one study, 47 patients with varicose veins treated with Bilberry  extract (480 mg per day) witnessed significant improvement with edema, heaviness feeling, parethesia, pain and skin dystrophy.^19,20 ( see also Horse chestnut and Grape seed extract in this document).

Dosage and Standardized Grade

For most eye conditions and capillary fragility conditions, the following recommendations can be considered:

80 to 160 mgs of Bilberry extract, (standardized to 25 percent anthocyanidin content),   three times per day.

Adverse Side Effects, Toxicity and Contraindications

Bilberry  extract has been shown to be very non toxic and has not produced any significant side effects is studies to date. There are no well known health conditions that preclude the use of Bilberry  extract.^21,22

Drug-Nutrient Interactions

Anticoagulant Medications (e.g. warfarin, coumadin, aspirin) – as Bilberry  extract has been shown in experimental studies to reduce the clotting action of blood platelets, it may potentiate the action of other anticoagulant drugs.  In these cases, prothrombin time (INR) should be monitored closely to guard against a possible bleeding disorder, although no human reports of such an occurrence have yet been reported.²⁴

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