How It Works
Bottom Line: Bilberry can help improve vision in people with cataracts and macular degeneration. There is no evidence to support its other uses.
In laboratory studies, bilberry reduces inflammation and edema (accumulation of fluid in the tissues), acts as an antioxidant, inhibits blood clotting, and strengthens the walls of the blood vessels. These studies also suggest that bilberry inhibits an enzyme called cAMP phosphodiesterase, which is essentially the same action that caffeine has in the body. The extracts of bilberry can inhibit the growth of cancer cells in the lab. Although most of these effects have not been studied in humans, preliminary clinical trials indicate that bilberry strengthens and protects the walls of the blood vessels in humans. More clinical trials are needed to confirm this effect.
In addition, compounds isolated from bilberry called anthocyanins are able to regenerate rhodopsin, the pigment found in retina cells responsible for eyesight. This finding explains bilberry's success in improving vision in patients with mascular degeneration, glaucoma and cataracts.
Purported Uses
To prevent cancer
Laboratory studies suggest some anti-cancer effects, but there is no proof from clinical trials that bilberry can treat cancer in humans.
To treat cataracts
Several clinical trials support this use.
To treat diabetic retinopathy (degeneration of the retina due to diabetes)
Several clinical trials support this use.
To treat glaucoma
Several clinical trials support this use.
To prevent the progression of macular degeneration
Several clinical trials support this use.
To reduce inflammation in conditions such as hemorrhoids or mucositis
Laboratory studies suggest anti-inflammatory effects, but there is no proof from clinical trials that bilberry can reduce inflammation in humans.
To improve vision, especially at night
Clinical trials show that bilberry improves eyesight in patients with certain disorders, but do not support this use in individuals with good vision.
To treat diarrhea
No scientific evidence supports this use.
To treat circulatory disorders
Laboratory studies show that bilberry may protect blood vessels and decrease the risk of blood clots, but there is no proof from clinical trials that bilberry can effectively treat circulatory disorders.
To improve the appearance of varicose veins
No scientific evidence supports this use.
Research Evidence
Vision and Diabetic Retinopathy
Researchers have performed several clinical trials with bilberry and have found no short- or long-term improvements in night vision. Numerous clinical studies have shown that bilberry (in standardized extract form of 25% anthocyanosides) is effective in preventing diabetic retinopathy and improving both vision and retina function.
A small crossover clinical trial assessed the ability of bilberry to improve night vision in 15 healthy male Air Force personnel with 20/20 vision. Eight men took bilberry extract (standardized to 25% anthocyanosides) and seven men took a placebo pill for the first three-week period. After one month of "washout" (no treatment), the men switched to the other treatment: the eight took placebo and the other seven took bilberry extract. No change was detected in night vision in either group of men. This study does not support the use of bilberry for night vision in people with no prior sight problems, but its results may not apply to those with retina dysfunction.
Warnings
This product is regulated by the F.D.A. as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Bilberry fruit should not be confused with bilberry leaf, which may lower blood sugar levels.
Do Not Take If
You use warfarin or other blood thinners (bilberry may increase the risk of bleeding).
You have a blood clotting disorder such as hemophilia (bilberry may increase the risk of bleeding).
Side Effects
None known
Scientific Name
Common Name
Dwarf bilberry, bog bilberry, European blueberry, huckleberry, and whortleberry
Clinical Summary
Derived from the fruit of the tree. Several human studies suggest that bilberry anthocyanosides prevent diabetic retinopathy and improve visual acuity and retinal function
(6) (7) (8) (9). In vitro studies suggest bilberry has anticancer activities
(10) (11) (14) (15) (16). Coumarins present in bilberry may interact with platelets and have an additive effect with blood thinners
(5). No adverse reactions have been reported. Bilberry fruit should not be confused with bilberry leaf, which may cause hypoglycemia.
Purported uses
Cancer prevention
Cataracts
Circulatory disorders
Diabetic retinopathy
Diarrhea
Glaucoma
Hemorrhoids
Macular degeneration
Mucositis
Varicose veins
Visual acuity
Constituents
Tannins: 5-10% catechin tannins
Carbohydrates: 30% invert sugar and pectins
Flavonols: Flavonol glycosides including astragalin, hyperoside, isoquercitrin and quercetin
Phenolic acids
Anthocyanosides
(1)
Mechanism of Action
The anthocyanins in bilberry contribute to most of its pharmacological activities. Anthocyanin has anti-inflammatory, vasoprotective
(12), and antioxidant effects
(13). It has demonstrated free radical scavenging and inhibition of cAMP phosphodiesterase actions. Extract of bilberry can inhibit human leukemia cells and human colon carcinoma cells growth through the induction of apoptosis
(10). In vitro and in vivo clinical studies show inhibition of platelet aggregation and stimulation of vascular prostacyclin. Bilberry anthocyanins regenerate rhodopsin and are indicated in treatment of poor night vision, mascular degeneration, glaucoma and cataracts
(2) (3) (4)
Pharmacokinetics
Intravenous and oral studies were performed in male rats with bilberry anthocyanosides. Oral administration showed moderate GI absorption with bioavailability less than 2%. Peak levels were achieved within 15 minutes with a three-compartment distribution and elimination shown. Elimination was primarily through urine and bile. There are no reports regarding whole bilberry extract pharmacokinetics.
(4)
Adverse Reactions
None reported.
Herb-Drug Interactions
Anticoagulants / Antiplatelets:Bilberry may potentiate the risk of bleeding if used concurrently due to platelet aggregation inhibition and prostaglandin modulation.
Lab Interactions
Coumarin content in bilberry may increase PT/PTT and inhibit platelet activity.
(5)
Literature Summary and Critique
Several clinical trials have found no short- or long-term improvements in night vision attributable to bilberry. Numerous human studies have shown that bilberry in standardized extract form of 25% anthocyanosides is effective in preventing diabetic retinopathy and improving visual acuity and retinal function.
(6) (7) (8) (9) Muth ER, Laurent JM, Jasper P. The effect of bilberry nutritional supplementation on night visual acuity and contrast sensitivity. Altern Med Rev 2000;5:164-73.A prospective, randomized, placebo-controlled crossover evaluation of bilberry supplementation in 15 healthy male Air Force personnel. All subjects had visual acuity of 20/20 or better at baseline. Two 3-week treatment periods with a 1-month washout period between evaluated effects of bilberry or placebo on night visual acuity and night contrast sensitivity. No change was detected in either outcome. Bilberry did not augment night visual acuity or contrast sensitivity in subjects with no prior deficiencies.
References
- Bisset NG, et al. Herbal Drugs and Phytopharmaceuticals, 2nd ed. Boca Raton: Medpharm CRC Press; 1994.
- Blumenthal, et al. Herbal Medicine Expanded Commission E Monographs, 1st ed. Austin: American Botanical Council; 2000.
- Bruneton, J. Pharmacognosy, Phytochemistry, Medicinal Plants. Paris: Lavoisier Publishing; 1995.
- Morazzoni P, et al. Vaccinium myrtillus anthocyanosides pharmacokinetics in rats. Arzneimittel-Forschung 1991;41:128-31.
- Brinker F. Herb Contraindications and Drug Interactions 3rd ed. Sandy (OR): Eclectic Medical; 2001.
- Muth ER, et al. The effect of bilberry nutritional supplementation on night visual acuity and contrast sensitivity. Altern Med Rev 2000;5:164-73.
- Zadok D, et al. The effect of anthocyanosides on night vision tests. Invest Ophthalmol Vis Sci 1997;38(suppl):633.
- Boniface R,et al. Pharmacological properties of mytillus anthocyanosides: correlation with results of treatment of diabetic microangiopathy. Flavonoids Bioflavonoids. Ireland: Elsevier; 1985, 293-301.
- Perossini M, et al. Diabetic and hypertensive retinopathy therapy with anthocyanosides double blind placebo-controlled clinical trial. Ann Ottal Clin Ocul 1987;113:1173-90.
- Katsube N, et al. Induction of apoptosis in cancer cells by Bilberry (Vaccinium myrtillus) and the anthocyanins. J Agric Food Chem. 2003 Jan 1;51(1):68-75.
- Bagchi D, Sen CK, Bagchi M, Atalay M. Anti-angiogenic, antioxidant, and anti-carcinogenic properties of a novel anthocyanin-rich berry extract formula. Biochemistry (Mosc). 2004 Jan;69(1):75-80
- Lietti A, et al. Studies on Vaccinium myrtillus anthocyanosides. I. Vasoprotective and antiinflammatory activity. Arzneimittelforschung. 1976;26(5):829-32.
- Laplaud PM, et al. Antioxidant action of Vaccinium myrtillus extract on human low density lipoproteins in vitro: initial observations. Fundam Clin Pharmacol. 1997;11(1):35-40.
- Lala G, Malik M, Zhao C, et al. Anthocyanin-rich extracts inhibit multiple biomarkers of colon cancer in rats. Nutr Cancer. 2006;54(1):84-93.
- Misikangas M, Pajari AM, Päivärinta E, et al. Three Nordic berries inhibit intestinal tumorigenesis in multiple intestinal neoplasia/+ mice by modulating beta-catenin signaling in the tumor and transcription in the mucosa. J Nutr. 2007 Oct;137(10):2285-90.
- Teller N, Thiele W, Marczylo TH, et al. Suppression of the kinase activity of receptor tyrosine kinases by anthocyanin-rich mixtures extracted from bilberries and grapes. J Agric Food Chem. 2009 Apr 22;57(8):3094-101.
