Bilberry is a good example of an herbal medicine that is representative of a current trend in the interest in fruits with high anthocyanin content. Not only are these supplements and foods safe, but they are potent antioxidants, of a class that are just beginning to be understood and appreciated. The anthocyanin antioxidant compounds are also often helpful for maintaining vascular, cardiovascular and eye health. Bilberry’s main active components are the flavonoids called anthocyanidins, of which there are many in bilberry, and the carotenoids (zeaxanthin and lutein) (McKenna et al, 2001).
Bilberry has been used in several therapeutic applications due to its wide range of activities. Bilberry has been reported to be vasoprotective, antiedemic, antioxidant, anti-inflammatory, anti-ulcer, and astringent. The anthocyanosides in bilberry are known to exhibit many functions, including collagen-stabilizing and reinforcing activity, decreasing capillary permeability, relaxing smooth musculature, increasing urinary output, and increasing the contractile strength of the myocardium, a few of the key preclinical studies are listed below (McKenna et al., 2001):
•An extract of bilberry was tested for its effects on microvascular permeability in a hamster cheek pouch model of ischemia reperfusion injury. Bilberry caused a significant reduction in microvascular impairment, preservation of arteriolar tone, reduced number of leukocytes adhering to venular walls, preservation of capillary perfusion, and an increase in microvascular permeability (Bertuglia et al., 1995).
•Detre et al. (1986) tested the effect of bilberry on vascular permeability in rats with induced hypertension. Bilberry was found to bring the vascular permeability, which is increased in hypertensive states, back to normal levels in the hypertensive rat model.
•Bilberry has been shown to have an anti-aggregatory activity similar to acetylsalicylic acid, and in a study with 30 volunteers, it was shown to inhibit aggregation at the first 30 and 60 days, but return to normal after 120 days. This study was able to support the theory that bilberry’s action depends on an increase in cyclic AMP and/or platelet thromboxane A2 (Pulliero et al., 1989).
•Bilberry has been found to exhibit a protective effect on the capillary walls by stabilizing membrane phospholipids and by increasing connective tissue biosynthesis (Mian et al., 1977).
•Bilberry has exhibited antioxidant activity in a number of antioxidant models. An extract in mice with induced liver peroxidation showed significant antioxidant activity at doses of 250 and 500 mg/kg p.o (Martín-Aragón et al., 1999).
Bilberry seems to be a safe and efficacious preventative to degenerating vascular illnesses, and an excellent dietetic aid for diabetics for the prevention of macular degeneration. As the population in the U.S. ages, it is sure to need good, safe, preventatives of age-related degeneration such as bilberry.
Bilberry extract (Tegens® at 160 mg, 240 mg, or 340 mg daily) administered to pregnant patients exhibiting venous insufficiency of the lower limbs or acute hemorrhoids caused a progressive amelioration of symptoms during the 3 month of treatment. The symptoms were reduced by: 94.6% for pruritus; 87.5% for paresthesias; 80.1% for cramps; 78.5% for pain; 60% exhaustion and the sensation of heaviness; and 75-83% for hemorrhoids. No side effects or adverse reactions were found for either mothers or the babies included in the study (Teglio et al., 1987).
Boniface et al. (1985) confirmed pharmacological evidence in experimental studies that bilberry’s anthocyanosides reduce the biosynthesis of polymeric collagen and glycoproteins (that are responsible for the vascular complications in diabetics), and compared this to a couple of clinical studies involving diabetics. The clinical studies administered bilberry anthocyanosides to diabetics, and found increases in vascular health; thus, confirming the pharmacological findings.
Bilberry anthocyanosides (Tegens® at 480 mg daily for 30 days) administered to patients with venous diseases characterized by phlebopathic stasis significantly improved measures of venous health compared to conventional treatments. Symptoms monitored were limb heaviness, pain levels, dyschromic and dystrophic skin phenomena, and limb edema (Ghiringhelli et al., 1978).
Patients with retinopathies were administered bilberry anthocyanosides (Tegens® at 160 mg daily) in a preliminary study. In the treatment phase of the study, 50% showed improvements vs. only 20% in the control group. In those patients with hard exudates in the back pole, 35% in the control phase worsened over the course of the study vs. 20% of the treatment group. In those with circinate disposition of the hard exudates, 15% worsened in the control group vs. 10% in the treatment group (Repossi et al., 1987).
Bravetti et al. (1987) examined the effects of anthocyanosides from bilberry extract administered with vitamin E (180 mg of a 25% standardized extract and 100 mg vitamin E) in patients with mild senile cortical cataracts. The treatment was found to reduce lens opacity in 97% of the cases examined.
A double-blind, placebo-controlled crossover study examined the effect of bilberry extract (Tegens® at 160 mg, twice daily) in 14 patients with diabetes or hypertension. An improvement of 77-90% in clinical symptomology was found for the patients after one month, and bilberry was concluded to be a safe and effective therapy (Perossini et al., 1987).
Anthocyanosides from bilberry (Tegens® at 480 mg three times daily) were administered to 10 patients with diabetic retinopathy in a pilot study. In the course of the study (6 months) improvements were seen in the retinal picture of all patients. The authors concluded bilberry to be of strong promise in the therapy of diabetic retinopathy (Orsucci et al., 1983).
Patients with various retinopathies were administered bilberry (Difarel 100® at 200 mg, three times daily) and were found to have improvements in their conditions. The authors noted that improvements in the hemorrhagic tendency and vascular permeability, while being improved in all participants, were most evident in those with diabetic retinopathy (Scharrer and Ober, 1981).
Bilberry extract was administered to normal subjects at 300 mg daily in a placebo-controlled study. Significant improvements were found in measures of visual health: adaptive ability to light and dark, macular recuperation time, and chromatic discrimination (Sala et al., 1979).
An anthocyanoside rich extract of bilberry was administered to 40 normal subjects in a placebo-controlled trial to test its effect on various aspects of visual health. In the treatment group, improvements were found in all tested visual functions, including darkness adaptation, macular sensitivity, and adapto-cinematographic thresholds compared to placebo (Jayle and Aubert, 1964).
Under conditions of food rationing and little or no fruits, during WWII, the British Royal Air Force pilots were reported to use bilberry to improve their night vision. Subsequently, numerous clinical studies were performed to try to confirm this effect (McKenna et al., 2001). In one of these studies, the long-term administration of a bilberry extract (Difrarel 100®- 100 mg of anthocyanosides and 0.005 b-carotene; 4 tablets daily for 8 days) showed improvements in visual functions of 14 air traffic controllers. The results found decreased dazzling effect; decreased visual fatigue, and a quicker adaptation of scotopic vision (Belleoud et al., 1966).
Safety / Dosage
Bilberry dosages are usually recommended in the range of 240-640 mg daily for most uses (usually 500 mg), and less than 300 mg/daily for eye health. Bilberry extracts are usually based on anthocyanoside content, and a 25% standardized extract is the standard preparation (McKenna et al., 2001):
Bilberry is quite safe, as it is also a traditional food, and the only reported side effects of bilberry have been digestive disturbances. This has not yet been clearly investigated and it is possible that most of these reports were idiosyncratic. Furthermore, bilberry is often formulated with minerals, and these are well-known to cause some digestive disturbance when taken without food (McKenna et al., 2001).
Very high doses of bilberry have a blood thinning action, and should be avoided with use of warfarin or antiplatelet drugs (McKenna et al., 2001).
1.Belleoud L, Leluan D, Boyer Y. [Study on the effects of anthocyanin glucosides on the nocturnal vision of air traffic controllers]. Revue de Medecine Aeronautique et Spatiale 1966; 3:45.
2.Bertuglia S, Malandrino S, Colantuoni A Effect of Vaccinium myrtillus anthocyanosides on ischaemia reperfusion injury in hamster cheek pouch microcirculation. Pharmacol Res. 1995 Mar-Apr;31(3-4):183-7.
3.Boniface R, Miskulin M, Robert L et al. Pharmacological properties of myrtillus anthocyanosides: correlation with results of treatment of diabetic microangiopathy, in: Farkas, L.; M. Gabor; and F. Kallay (eds.), Flavonoids and Bioflavonoids: Proceedings of the 7th Hungarian Bioflavonoid Symposium. 1985; Budapest, Hungary: Akademiai Kiado.
4.Bravetti GO, Fraboni E, Maccolini E. Preventive medical treatment of senile cataract with vitamin E and Vaccinium myrtillus anthocyanosides: clinical evaluation. Annali di Ottalmologia e Clinica Oculistica 1987; 115:109-116.
5.Detre Z, Jellinek H, Miskulin M, Robert AM. Studies on vascular permeability in hypertension: action of anthocyanosides. Clin Physiol Biochem. 1986;4(2):143-9.
6.Ghiringhelli C, Gregoratti L, Marastoni F. Capillarotropic action of anthocyanosides in high dosage in phlebopathic statis. Minerva Cardioangiol. 1978 Apr;26(4):255-76.
7.McKenna DJ, Jones K, Hughes K (eds). Botanical Medicines: A Desktop Reference for the Major Herbal Supplements. 2001 Haworth Press: New York
8.Martín-Aragón S, Basabe B, Benedi JM et al. In vitro and in vivo antioxidant properties of Vaccinium myrtillus. Pharmaceutical Biology1999; 37:109-113.
9.Mian E, Curri SB, Lietti A. et al. Anthocyanosides and microvessels wall:new findings on the mechanism of action of their protective effect in syndromes due to abnormal capillary fragility. Minerva Medica 1977; 68:3565-3581.
10.Perossini M, Guidi G, Chiellini S. et al. [Diabetic and hypertensive retinopathy therapy with Vaccinium myrtillus anthocyanosides (Tegens): double-blind, placebo-controlled clinical trial. Annali di Ottalmologia e Clinica Oculistica 1987; 113:1173-1190.
11.Pulliero G, Montin S, Bettini V. et al. Ex vivo study of the inhibitory effects of Vaccinium myrtillus anthocyanosides on human platelet aggregation. Fitoterapia 1989; 55:69-74.
12.Repossi P, Malagola R, De Cadilhac C. The role of anthocyanosides on vascular permeability in diabetic retinopathy. Annali di Ottalmologia e Clinica Oculistica 1987; 113:357.
13.Scharrer A, Ober M. Anthocyanosides in the treatment of retinopathies. Klinische Monatsblatter für Augenheilkunde1981; 178:386-389.
14.Teglio L, Mazzanti C, Tronconi T et al. Vaccinium myrtillus anthocyanosides (Tegens) in the treatment of venous insufficiency of the lower limbs and acute hemorrhoids in pregnancy. Quaderni di Clinica Ostertrica e Ginecologica 1987; 42:221-231.
EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.