Herbal Monograph
Bilberry
Vaccinium myrtillus L.
Ericaceae (Ericales)
Premier European berry for vascular protection, retinal health, and astringent healing of the gut.
Overview
Plant Description
Bilberry is a low-growing, deciduous, rhizomatous dwarf shrub that forms extensive ground-cover colonies in acidic, nutrient-poor soils. The plant reaches 10-50 cm (4-20 inches) in height, with numerous erect, angular to narrowly winged, bright green stems that are glabrous (smooth) and sharply angled in cross-section. The stems are heavily branched, creating a dense, bushy habit. The root system is shallow and fibrous, with creeping rhizomes that allow vegetative spread; roots can reach depths of up to 1 metre. Individual plants may live up to 30 years. The leaves are simple, alternate, 1-3 cm long, ovate to broadly elliptic or lanceolate, with finely serrate (toothed) margins that bear small glandular teeth. Leaves are bright green above with prominent venation on the lower surface, turning vivid red in autumn before being shed. Flowers appear in April to June, borne singly (occasionally in pairs) in the leaf axils on short, drooping peduncles. The corolla is nearly globular (urceolate), 4-6 mm long, pale pink to greenish-pink with a waxy texture, with 4-5 recurved lobes at the mouth. Pollination is primarily by bees (Bombus and Apis species). The fruit is a true berry, 5-9 mm in diameter, globose, initially green then ripening through red to blue-black with a distinct glaucous (waxy) bloom. Crucially, unlike cultivated blueberries (V. corymbosum), the flesh of bilberry is deeply pigmented dark red to purple throughout, not merely in the skin -- a direct consequence of its exceptionally high anthocyanin content distributed through all tissue layers. Each berry contains numerous small seeds. Fruits ripen from July to September. The species name 'myrtillus' is a diminutive of 'myrtus' (myrtle), referring to the resemblance of the leaves to those of myrtle.
Habitat
Bilberry grows primarily in acidic soils (pH 3.5-5.5) in heathlands, moorlands, degraded meadows, open and semi-open coniferous forests (particularly at the base of pine and spruce forests), boggy barrens, and montane slopes. It thrives in cool, humid climates with moderate rainfall and is tolerant of shade, though fruiting is significantly better in open or partially shaded situations. The species is characteristic of the understorey layer of boreal and subarctic forests and is a dominant ground-cover species in many European heathland ecosystems. It grows from lowland areas up to alpine elevations of approximately 2,350 metres (7,700 feet) in continental mountain ranges.
Distribution
Vaccinium myrtillus is a Holarctic species with a broad circumpolar distribution. It is native to virtually every country in Europe (from Scandinavia and the British Isles to the Mediterranean mountains and eastward through Russia), extending through northern and central Asia to Japan. Disjunct populations occur in western Canada (British Columbia) and the northwestern United States (Washington, Oregon, Montana). The species reaches its greatest abundance and ecological dominance in the boreal and subarctic zones of Scandinavia, Finland, Russia, and the Baltic states, where it forms vast carpets beneath coniferous forests. Wild-harvested bilberry fruits from Scandinavia, Finland, Poland, and the Baltic states constitute the bulk of commercial supply for the European herbal and food industries.
Parts Used
Fresh ripe fruit (Myrtilli fructus recens)
Preferred: Standardised dry extract of fresh fruit (25% anthocyanidins / 36% anthocyanins); fresh-frozen fruit; juice
The fresh or fresh-frozen ripe fruit is the primary source material for standardised anthocyanin-rich extracts. Fresh bilberry fruit contains a minimum of 0.30% anthocyanins expressed as cyanidin 3-O-glucoside chloride (European Pharmacopoeia standard). The therapeutic activity of fresh fruit preparations is primarily attributed to their anthocyanin content, which is responsible for the vasoprotective, antioxidant, and anti-inflammatory effects. Fresh fruit is the basis for the EMA/HMPC traditional use monograph for relief of symptoms related to chronic venous insufficiency (heaviness of legs, capillary fragility) and the starting material for commercial standardised extracts (Myrtocyan, Mirtoselect).
Dried ripe fruit (Myrtilli fructus siccus)
Preferred: Dried whole berries for decoction or chewing; powdered dried fruit for capsules or as tea
The dried ripe fruit is the traditional medicinal preparation and the drug described in the German Commission E positive monograph. Dried bilberry fruit contains a minimum of 1.0% tannins expressed as pyrogallol (European Pharmacopoeia). During drying, much of the anthocyanin content is degraded or converted, while the proanthocyanidin (condensed tannin) content becomes the dominant active fraction. The dried fruit's therapeutic activity is therefore primarily astringent (tannin-mediated), making it effective for diarrhoea and mild mucosal inflammations -- indications distinct from those of the fresh fruit extract. Commission E approved dried bilberry fruit for non-specific acute diarrhoea and topically for mild inflammation of the oropharyngeal mucosa.
Leaf (Myrtilli folium)
Preferred: Dried leaf infusion (short-term traditional use only); not recommended for standardised extract production
Bilberry leaf was historically used in European folk medicine, particularly as a hypoglycaemic remedy for diabetes before the discovery of insulin. The leaves contain flavonoids (quercetin glycosides), phenolic acids (chlorogenic acid, caffeic acid), chromium, catechins, and proanthocyanidins, but lack the anthocyanin content that characterises the fruit. IMPORTANT: Bilberry leaf is NOT included in the Commission E positive monograph and is NOT recommended for long-term use. The German Commission E issued a negative assessment for bilberry leaf due to insufficient evidence of efficacy for claimed antidiabetic effects and theoretical safety concerns with prolonged high-dose use (possible chronic toxicity from hydroquinone derivatives). Bilberry leaf should be distinguished clearly from the fruit in clinical application.
Key Constituents
Anthocyanins (anthocyanoside flavonoids)
Anthocyanins are the PRIMARY bioactive constituents of bilberry fruit (fresh) and its standardised extracts. Bilberry is one of the richest natural sources of anthocyanins among commonly consumed fruits, with total anthocyanin content typically 300-700 mg per 100 g fresh fruit -- 2-4 times higher than American blueberry (V. corymbosum). The 15 individual anthocyanins (5 aglycones x 3 sugar conjugates: glucoside, galactoside, arabinoside) create a unique and complex fingerprint profile that serves as an authenticity marker for genuine bilberry products. This anthocyanin profile is the basis for distinguishing bilberry from adulterants (particularly V. corymbosum). Anthocyanins are responsible for the vascular-protective, antioxidant, anti-inflammatory, visual function-supporting, and metabolic effects of bilberry. They act through multiple mechanisms: direct free radical scavenging, chelation of pro-oxidant metal ions, inhibition of NF-kB inflammatory signalling, enhancement of endothelial nitric oxide synthase (eNOS) activity, stabilisation of collagen and connective tissue matrices, and modulation of cell-signalling pathways (AMPK activation, MAPK modulation). Standardised bilberry extracts are typically standardised to 25% anthocyanidins (the sugar-free aglycone forms) or equivalently 36% anthocyanins (the glycosylated forms).
Proanthocyanidins (condensed tannins) and hydrolysable tannins
Proanthocyanidins (condensed tannins) are the therapeutically decisive constituents in DRIED bilberry fruit preparations, in contrast to the anthocyanin-dominated fresh fruit and its extracts. The astringent action of proanthocyanidins is the mechanistic basis for the well-established traditional use of dried bilberry for diarrhoea, confirmed by Commission E and EMA traditional use status. Tannin content is the quality marker for dried bilberry fruit in the European Pharmacopoeia (minimum 1.0% tannins expressed as pyrogallol). This critical distinction between fresh/frozen fruit (anthocyanin-rich, vasoprotective) and dried fruit (tannin-rich, astringent) underpins the two distinct therapeutic profiles of bilberry.
Flavonoids (non-anthocyanin)
Non-anthocyanin flavonoids, while present at lower concentrations than anthocyanins in the fruit, contribute synergistically to the overall antioxidant, anti-inflammatory, and vascular-protective effects of bilberry preparations. Quercetin in particular adds anti-allergic (histamine release inhibition), aldose reductase inhibitory, and anti-inflammatory activity. The catechin content contributes to cardiovascular protection through endothelial function enhancement. In bilberry leaf preparations, these non-anthocyanin flavonoids constitute a more prominent proportion of the total phenolic content.
Phenolic acids
Phenolic acids complement the anthocyanin and flavonoid activity by providing additional antioxidant and anti-inflammatory capacity. Chlorogenic acid is of particular relevance to the hypoglycaemic effects of bilberry, acting through inhibition of hepatic glucose-6-phosphatase and modulation of glucose absorption.
Iridoids (primarily in leaves)
Iridoids are primarily relevant to bilberry leaf preparations rather than fruit-based products. Their presence in leaves may contribute to the traditional folk medicine use of bilberry leaf for urinary complaints and inflammation, though leaf preparations are not recommended for therapeutic use based on current regulatory assessments.
Organic acids, pectins, and other constituents
Organic acids maintain the low pH environment that stabilises anthocyanins during storage and in gastric conditions. Pectins provide soluble fibre with prebiotic activity, contributing to gastrointestinal health. Vitamin C acts synergistically with anthocyanins in antioxidant defence. These constituents collectively contribute to the food-medicine character of bilberry fruit.
Herbal Actions
The hallmark pharmacological action of bilberry anthocyanins. Bilberry anthocyanosides stabilise and strengthen capillary walls, reduce capillary permeability, and improve microcirculation. The mechanism involves: (1) cross-linking and stabilising collagen fibres in the vascular basement membrane, (2) inhibiting enzymes that degrade connective tissue components of vessel walls (collagenase, elastase, hyaluronidase), (3) enhancing endothelial nitric oxide synthase (eNOS) activity and nitric oxide bioavailability, improving endothelium-dependent vasodilation, and (4) reducing vascular inflammation through NF-kB inhibition. Clinical evidence from studies of patients with chronic venous insufficiency (CVI), capillary fragility, diabetic retinopathy, and other microvascular disorders supports this action. A large registry study of 1,051 CVI patients demonstrated significant improvements in microcirculation and oedema with Mirtoselect bilberry extract. The vasoprotective effect of bilberry anthocyanosides has been reported to be approximately twice as potent as rutin in reducing capillary fragility, both in intensity and duration.
[2, 4, 5]Prevents or slows oxidative damage to cells
Bilberry is one of the most potent antioxidant-containing fruits in the human diet, attributable to its exceptionally high anthocyanin and total polyphenol content. The antioxidant activity operates through multiple mechanisms: direct scavenging of reactive oxygen species (superoxide anion, hydroxyl radical, peroxyl radicals, singlet oxygen), chelation of pro-oxidant transition metal ions (iron, copper), inhibition of lipid peroxidation, enhancement of endogenous antioxidant enzyme activity (superoxide dismutase, glutathione peroxidase, catalase), and upregulation of cellular antioxidant defences via Nrf2/ARE pathway activation. The ORAC (Oxygen Radical Absorbance Capacity) value of bilberry fruit ranks among the highest of commonly consumed berries. However, it is important to note that in vitro antioxidant capacity does not necessarily translate directly to in vivo antioxidant effects, as bioavailability of anthocyanins is relatively low (estimated 1-2% systemic bioavailability). The antioxidant action contributes to vasoprotective, neuroprotective, and anti-inflammatory effects.
[5, 7]Tightens and tones tissue, reduces secretions
The astringent action of DRIED bilberry fruit is well established and is the basis for the Commission E and EMA/HMPC approved indication for non-specific acute diarrhoea. This action is mediated by the proanthocyanidin (condensed tannin) content, which is concentrated during drying while anthocyanins are partially degraded. Tannins precipitate proteins on the mucosal surface of the gastrointestinal tract, forming a protective layer that reduces secretion, inhibits peristalsis, and diminishes mucosal inflammation. The European Pharmacopoeia specifies a minimum tannin content of 1.0% (expressed as pyrogallol) for dried bilberry fruit. This astringent action is specific to the DRIED fruit and is NOT a primary action of the standardised anthocyanin-rich extract of fresh fruit.
[1, 2, 3]Reduces inflammation
Bilberry anthocyanins and flavonoids demonstrate significant anti-inflammatory activity through multiple pathways: inhibition of NF-kB nuclear translocation and downstream pro-inflammatory gene expression, inhibition of cyclooxygenase (COX-1, COX-2) and lipoxygenase (5-LOX) enzymes, reduction of pro-inflammatory cytokine production (TNF-alpha, IL-1beta, IL-6), and inhibition of proteasome activity. Karlsen et al. (2010) demonstrated significant reductions in plasma inflammatory markers (hsCRP, IL-6) in subjects consuming bilberry juice (330 mL/day) for 4 weeks. The anti-inflammatory action contributes to the vasoprotective and gastrointestinal effects of bilberry.
[5, 7, 11]Bilberry has a long-standing reputation for supporting visual function, originating from the widely cited (but unverified) anecdote of British RAF pilots consuming bilberry jam before night bombing missions in World War II to improve night vision. The pharmacological basis for visual effects includes: (1) anthocyanins accelerate the regeneration of rhodopsin (visual purple) in retinal rod cells, which is essential for dark adaptation, (2) anthocyanins protect retinal pigment epithelium and photoreceptor cells from oxidative damage, (3) vasoprotective effects improve retinal microcirculation. However, a systematic review by Canter and Ernst (2004) of placebo-controlled trials concluded that the evidence does NOT support improvement of normal night vision in healthy individuals with bilberry anthocyanosides. The more recent and better-designed RCTs were negative for night vision improvement. Evidence is stronger for bilberry's protective role in retinal pathology (diabetic retinopathy, macular degeneration) where oxidative stress and microvascular damage are involved, though large confirmatory trials are needed.
[5, 9, 10]Bilberry fruit and leaf have a traditional reputation as antidiabetic remedies, and bilberry leaf was one of the most widely used herbal treatments for diabetes before the discovery of insulin. Modern research has identified multiple mechanisms: anthocyanin-mediated activation of AMP-activated protein kinase (AMPK) in adipocytes and muscle cells (improving insulin sensitivity), inhibition of alpha-glucosidase (slowing carbohydrate digestion), stimulation of insulin secretion from pancreatic beta cells, inhibition of hepatic glucose-6-phosphatase (reducing hepatic glucose output), and enhancement of glucose transporter (GLUT-4) translocation. Animal studies have shown plasma glucose reductions of 26-51% with bilberry extracts. However, well-designed human clinical trials specifically demonstrating blood glucose reduction in diabetic patients are limited. A single-dose human study (Mirtoselect 0.47 g, 36% anthocyanins) demonstrated reduced postprandial glycaemic response in diet-controlled type 2 diabetic patients. The hypoglycaemic effect is classified as mild because the clinical evidence in diabetic populations remains preliminary.
[5, 7, 16]Kills or inhibits the growth of microorganisms
Bilberry anthocyanins and polyphenols have demonstrated direct antimicrobial activity in vitro against several pathogens including Salmonella spp., Staphylococcus aureus, Bacillus cereus, and Escherichia coli. Additionally, bilberry polyphenols have been shown to potentiate antibiotic effects in some experimental systems. The antimicrobial action may contribute to the traditional use of bilberry for diarrhoeal illness (in combination with the astringent tannin action of dried fruit). However, clinical evidence for antimicrobial effects in vivo is limited, and the antimicrobial action should be considered supplementary rather than a primary therapeutic basis.
[5, 7]Therapeutic Indications
ophthalmological
Diabetic retinopathy (adjunctive support)
Diabetic retinopathy involves progressive damage to retinal microvasculature from chronic hyperglycaemia-induced oxidative stress, advanced glycation end-product (AGE) formation, and capillary basement membrane thickening. Bilberry anthocyanins address multiple pathological pathways: stabilising retinal capillary walls, reducing capillary permeability, providing antioxidant protection to retinal pigment epithelium and photoreceptors, and improving retinal microcirculation. Perossini et al. (1987) demonstrated significant improvement in ophthalmoscopic and fluoroangiographic parameters in patients with diabetic and hypertensive retinopathy treated with bilberry anthocyanosides (115 mg daily for 1 month) vs placebo. A more recent study with Mirtoselect (320 mg/day, 36% anthocyanins) showed improved retino-cortical bioelectrical activity (Visual Evoked Potential) in 44.4% of patients with severe diabetic retinopathy after 1 month. A registry study of 140 retinopathy patients found Mirtoselect supplementation represented an effective and safe integrated approach. Bilberry is used as adjunctive support, not as a replacement for standard ophthalmological management of diabetic retinopathy.
[4, 9, 15]Night vision and dark adaptation (traditional claim)
The claim that bilberry improves night vision in healthy individuals is among the most widely cited indications in popular literature, originating from the oft-repeated story of British RAF pilots consuming bilberry jam to improve night vision during WWII night bombing raids. However, a systematic review by Canter and Ernst (2004) of 12 placebo-controlled trials found that the 4 most rigorous and recent RCTs were ALL negative for night vision improvement. Only older, methodologically weaker studies reported positive effects. The reviewers concluded: 'The hypothesis that V. myrtillus anthocyanosides improves normal night vision is not supported by evidence from rigorous clinical studies.' This does NOT negate bilberry's value in retinal pathology (where evidence is more supportive), but the specific claim of improved night vision in healthy subjects with normal vision should be considered refuted by the weight of evidence.
[5, 10]Visual fatigue (asthenopia) and visual acuity
A randomised controlled trial of 30 subjects found that symptoms of asthenopia (visual fatigue, eye strain) and contrast sensitivity improved significantly after 4 weeks of purified bilberry anthocyanin supplementation (100 mg/day). Computer workers and individuals with high visual demands may benefit from bilberry supplementation for reducing visual strain, though larger confirmatory studies are needed. Additionally, a study combining Ginkgo biloba extract and bilberry anthocyanins demonstrated improved visual field in patients with normal-tension glaucoma.
[5, 14]Age-related macular degeneration (AMD, adjunctive)
The antioxidant and vasoprotective properties of bilberry anthocyanins are theoretically relevant to AMD, which involves progressive oxidative damage to the macula and retinal pigment epithelium. The high ORAC values of bilberry anthocyanins, combined with their demonstrated ability to accumulate in retinal tissue and protect photoreceptors from oxidative damage, provide a pharmacological rationale. However, clinical trial evidence specifically for bilberry in AMD is limited and insufficient to make definitive recommendations. Bilberry may be considered as part of a broader antioxidant strategy for macular health alongside lutein, zeaxanthin, and other evidence-based nutrients.
[4, 5]Cardiovascular System
Chronic venous insufficiency (CVI)
Chronic venous insufficiency -- characterised by leg heaviness, oedema, pain, and skin changes due to impaired venous return -- is one of the best-supported clinical indications for bilberry anthocyanin extract. The EMA/HMPC established a traditional use monograph for fresh bilberry fruit preparations for 'relief of symptoms of discomfort and heaviness of legs related to minor venous circulatory disturbances.' A large registry study of 1,051 CVI patients treated with venoactive agents including Mirtoselect (bilberry extract, 600 mg/day) demonstrated significant improvement in peripheral venous microcirculation and reduction of oedema. An earlier review of uncontrolled trials (1979-1985) on 568 CVI patients found anthocyanins effective in decreasing symptoms and improving both venous microcirculation and lymph drainage. A study of 47 patients with various venous diseases receiving 480 mg/day bilberry extract demonstrated reduced capillary flow and elimination of microstagnation and blood stasis in the foot.
[2, 4, 8]Capillary fragility and petechiae
Bilberry anthocyanins directly stabilise capillary walls by cross-linking collagen, inhibiting collagenase/elastase, and reducing capillary permeability. The EMA traditional use monograph for fresh bilberry fruit includes 'relief of symptoms of fragility of skin capillaries such as presence of petechiae.' This is one of the earliest and most consistently documented clinical effects of bilberry anthocyanins. The capillary-stabilising effect has been reported to be approximately twice as potent as rutin in both intensity and duration.
[2, 3, 4]Varicose veins
The vasoprotective and anti-oedema actions of bilberry anthocyanins provide a rational basis for use in varicose veins. ESCOP lists varicose vein and venous problems among the therapeutic indications for bilberry fruit. Symptom improvement (leg heaviness, pain, swelling) has been reported in clinical observations, though large-scale controlled trials specifically for varicose veins are limited. Bilberry is often combined with other venotropic agents (horse chestnut, butcher's broom, grape seed extract) in clinical practice.
[3, 4]Hemorrhoids
Haemorrhoids involve varicose veins of the anorectal plexus with associated inflammation, and bilberry's vasoprotective and anti-inflammatory actions are pharmacologically relevant. Bilberry has been reported as safe and efficacious for the treatment of gestational haemorrhoids and venous insufficiency of pregnancy. Clinical evidence is primarily from uncontrolled studies and traditional use, though the strong pharmacological rationale and favourable safety profile support its consideration as part of a comprehensive haemorrhoid management approach.
[3, 4]Dyslipidaemia (adjunctive)
Qin et al. (2009) found that 120 mg/day of a mixed bilberry and blackcurrant anthocyanin extract in 60 dyslipidaemic subjects for 12 weeks produced an approximately 14% decrease in LDL cholesterol and 14% increase in HDL cholesterol. Karlsen et al. (2010) reported reductions in inflammatory markers but no significant changes in cholesterol or triglycerides with bilberry juice supplementation. The evidence for lipid-modifying effects is mixed and based on limited studies, some using mixed anthocyanin preparations rather than pure bilberry extract.
[5, 11, 12]gastrointestinal
Non-specific acute diarrhoea
This is the BEST-ESTABLISHED indication for dried bilberry fruit, supported by Commission E approval, ESCOP monograph, and EMA/HMPC traditional use recognition. The mechanism is astringent (tannin-mediated): proanthocyanidins in dried bilberry fruit precipitate proteins on the gastrointestinal mucosal surface, forming a protective layer that reduces intestinal secretion and motility. IMPORTANT: This indication applies specifically to DRIED bilberry fruit (Myrtilli fructus siccus), not fresh fruit or standardised anthocyanin extracts. The Commission E monograph approves dried bilberry fruit for non-specific acute diarrhoea. The EMA/HMPC traditional use monograph for dried bilberry fruit covers 'symptomatic treatment of mild diarrhoea.' Traditionally, dried bilberries were chewed or made into a decoction for this purpose.
[1, 2, 3]Mild inflammation of the oropharyngeal mucosa
Commission E and EMA/HMPC approve topical use of dried bilberry fruit preparations (decoction used as a mouthwash or gargle) for mild inflammation of the oral and pharyngeal mucosa. The astringent tannins form a protective film on the inflamed mucosa, reducing pain, swelling, and exudation. This is a topical application of the same astringent mechanism that underlies the antidiarrhoeal indication.
[1, 2]Colitis and inflammatory bowel conditions (adjunctive)
The anti-inflammatory (NF-kB inhibition) and antioxidant activity of bilberry anthocyanins, combined with the astringent tannin action of dried fruit, provide a pharmacological rationale for adjunctive use in inflammatory bowel conditions. The pilot study by Thomasset et al. (2009) demonstrated accumulation of anthocyanin metabolites in colorectal tissue (up to 179 ng/g) and a 7% reduction in tumour cell proliferation in colorectal cancer patients consuming Mirtocyan (standardised bilberry extract). While this study focused on cancer chemoprevention rather than colitis, it demonstrates that oral anthocyanins reach and are bioactive in colonic tissue. Larger clinical trials are needed to validate use in inflammatory bowel disease.
[7, 13]Endocrine System
Type 2 diabetes mellitus (adjunctive support)
Bilberry has a centuries-long folk medicine tradition for diabetes management. Bilberry leaf was one of the most widely used plant remedies for diabetes before insulin's discovery. Modern research has identified multiple anti-diabetic mechanisms in the fruit anthocyanins: AMPK activation improving insulin sensitivity (Takikawa et al. 2009, in diabetic mice), alpha-glucosidase inhibition, stimulation of insulin secretion, and inhibition of hepatic glucose output. Animal studies show 26-51% plasma glucose reductions. However, well-designed human clinical trials in diabetic patients are very limited. A single-dose study of Mirtoselect (36% anthocyanins) demonstrated reduced postprandial glycaemic response in diet-controlled type 2 diabetic patients. Bilberry is NOT a substitute for standard antidiabetic therapy but may be considered as a complementary approach for metabolic support under practitioner supervision.
[5, 7, 16]dermatological
Capillary fragility with subcutaneous bleeding (easy bruising, petechiae)
The capillary-stabilising action of bilberry anthocyanins directly addresses increased capillary fragility that manifests as easy bruising and petechiae. By strengthening capillary walls and reducing permeability, bilberry reduces the tendency for microhaemorrhages into the skin and subcutaneous tissue. This indication is supported by the EMA/HMPC traditional use monograph for fresh bilberry fruit, which includes 'relief of symptoms of fragility of skin capillaries such as presence of petechiae.' It is particularly relevant in elderly patients with age-related capillary fragility or in patients with corticosteroid-induced skin thinning.
[2, 4]Musculoskeletal System
Peripheral vascular disorders (Raynaud's syndrome)
Bilberry's vasoprotective and microcirculation-enhancing properties provide a rationale for use in peripheral vascular conditions including Raynaud's syndrome (episodic vasospasm of digital arteries). Traditional herbal sources list Raynaud's syndrome among bilberry's indications. The mechanism would involve improved microvascular blood flow, enhanced endothelial nitric oxide production, and reduced capillary fragility. Clinical evidence specific to Raynaud's is limited, and use is based primarily on traditional practice and pharmacological rationale.
[3, 4]Energetics
Temperature
cool
Moisture
dry
Taste
Tissue States
hot/excitation, damp/relaxation, damp/stagnation
In Western herbal energetics, bilberry fruit is considered cool in temperature and mildly drying in moisture -- a profile consistent with its high tannin (astringent) and anthocyanin (antioxidant, anti-inflammatory) content. The sour taste reflects its organic acid content (citric, malic, quinic acids) and astringency from tannins. The sweet taste is a secondary quality from natural fruit sugars. The cooling, astringent nature makes bilberry particularly well-suited to conditions characterised by heat and laxity: inflamed, leaky capillaries (heat/excitation of the vascular endothelium), oedematous tissues with poor venous return (damp/relaxation of venous tone), and loose, watery stools (damp/relaxation of the intestinal mucosa). The astringent and toning action of bilberry addresses damp/stagnation in the venous and lymphatic circulation. Bilberry is thus most specifically indicated for constitutions or conditions presenting with signs of vascular heat, laxity, and congestion -- the classic picture of chronic venous insufficiency with oedema, capillary fragility, retinal microvascular damage, and damp intestinal conditions. It is less suited to conditions of dryness and deficiency. CAVEAT: Herbal energetics are interpretive frameworks within Western herbalism, not standardised across all practitioners.
Traditional Uses
European folk medicine (medieval through 18th century)
- Dried berries used as a remedy for diarrhoea, dysentery, and intestinal inflammation (widespread across Europe)
- Fresh berries consumed to improve vision and treat night blindness
- Leaf and fruit preparations used to manage symptoms of diabetes and to lower blood sugar
- Topical application of crushed fresh berries or decoction for wounds, skin ulcerations, and haemorrhoids
- Gargle or mouthwash of dried berry decoction for sore throat and mouth inflammation
- Used to treat scurvy (as a source of vitamin C, though bilberry is not particularly rich in it)
- Leaf tea used as a urinary antiseptic and for urinary tract complaints
"Bilberry has been used in European folk medicine for centuries. Hildegard of Bingen (12th century) mentioned the use of bilberry for intestinal complaints. In 18th-century German folk medicine, dried bilberries were standard household remedies for diarrhoea and dysentery. Swedish and Finnish traditional medicine used bilberry extensively as both food and medicine, with dried berries kept as an essential winter provision and home remedy. The Eclectic physicians of 19th-century America adopted bilberry (and related Vaccinium species) for diarrhoea and urinary complaints."
World War II era (1940s) and post-war European phytotherapy
- RAF (Royal Air Force) pilots reportedly consumed bilberry jam before night bombing missions to improve night vision and dark adaptation
- Post-war French and Italian researchers investigated bilberry anthocyanins for visual function, leading to the development of standardised extracts
- Development of Myrtocyan (standardised bilberry anthocyanin extract) in Italy in the 1960s-1970s for clinical use in vascular and ophthalmological conditions
- Widespread prescription of bilberry extracts by European physicians for retinopathy, chronic venous insufficiency, and capillary fragility from the 1970s onwards
"The story of British RAF pilots eating bilberry jam to improve their night vision during World War II became the most widely cited origin story for modern bilberry research. While the historical accuracy of this anecdote has been questioned (some historians suggest it may have been wartime propaganda to conceal the development of airborne radar), it catalysed scientific interest in bilberry's effects on vision. Post-war French and Italian pharmacological research in the 1960s-1970s led to the development of standardised anthocyanin extracts (notably Myrtocyan/Tegens by Inverni della Beffa in Italy), which became prescription or over-the-counter medicines for vascular and ophthalmic conditions throughout continental Europe."
British Herbal Pharmacopoeia and British Herbal Compendium
- Dried bilberry fruit listed for diarrhoea, dysentery, and haemorrhoids
- Astringent action on the gastrointestinal tract
- Topical use for haemorrhoids and oral mucosal inflammation
- Fresh fruit and extract for vascular support and peripheral circulatory disorders
"The British Herbal Pharmacopoeia (BHP) and British Herbal Compendium include bilberry fruit as an astringent remedy, primarily indicated for diarrhoea and gastrointestinal inflammation. The BHP specifies the dried ripe fruit as the therapeutic part. Additionally, bilberry fruit is included in the European Pharmacopoeia (both fresh and dried forms) and in the British Pharmacopoeia with three related monographs."
Scandinavian traditional food-medicine
- Fresh bilberries consumed in large quantities as a seasonal food and health-promoting staple
- Bilberry soups, jams, and sauces as traditional fare throughout Scandinavia and Finland
- Dried bilberries as a winter provision and home remedy for digestive complaints
- Bilberry leaf tea for blood sugar management and as a general tonic
- Fresh berries applied to burns and skin conditions
"In Scandinavian and Finnish culture, bilberry holds a unique position as both a beloved wild food and a traditional medicine. Wild bilberry picking is a deeply embedded cultural practice in Finland, Sweden, Norway, and other Nordic countries, with 'Everyman's Right' (allemansratten) guaranteeing public access to forage wild berries on any land. Finland alone is estimated to have over 1.5 billion kg of wild bilberries ripening annually, of which only a fraction is harvested. The cultural significance of bilberry as both food and medicine in Scandinavia extends back many centuries."
Modern Research
Comprehensive review of bilberry chemistry, pharmacology, and clinical evidence
Chapter in 'Herbal Medicine: Biomolecular and Clinical Aspects' (2nd edition, CRC Press) providing a comprehensive overview of V. myrtillus chemistry, antioxidant mechanisms, clinical evidence for vision, cardiovascular, metabolic, and anti-cancer effects, and safety. Extensively referenced review article that serves as a primary secondary source for bilberry monograph data.
Findings: Documented 15 anthocyanins as the primary bioactive compounds, with total content of 300-700 mg per 100 g fresh fruit. Confirmed antioxidant activity through multiple mechanisms (radical scavenging, metal chelation, enzyme modulation). Reviewed cell-signalling effects beyond simple antioxidation (NF-kB inhibition, AMPK activation, gene expression modulation). Noted rapid but low-efficiency absorption of anthocyanins (peak plasma 1-2 hours post-ingestion, approximately 1-2% systemic bioavailability). Identified significant product quality variability in commercial bilberry supplements (measured anthocyanin content 10-2000 micromol/g; some products claimed 250 mg/g but contained less than 10 mg/g). Concluded that well-designed human trials using standardised bilberry extracts are needed for most indications.
Limitations: Narrative review, not a systematic review with formal quality assessment. Many studies reviewed were preclinical (in vitro or animal models). Heterogeneity of bilberry preparations across studies limits comparability. Product quality variability complicates interpretation of clinical evidence.
[5]
Bilberry anthocyanosides for night vision: systematic review of placebo-controlled trials
Systematic review by Canter and Ernst (2004) evaluating the evidence for bilberry anthocyanosides improving night vision. Identified 30 trials with relevant visual outcome measures, of which 12 were placebo-controlled.
Findings: Of 12 placebo-controlled trials identified, the 4 most recent and methodologically rigorous RCTs were ALL negative for night vision improvement. A fifth RCT and 7 non-randomised controlled trials reported positive effects. Healthy subjects with normal or above-average eyesight were tested in 11 of 12 trials. Concluded that 'the hypothesis that V. myrtillus anthocyanosides improves normal night vision is not supported by evidence from rigorous clinical studies.' This systematic review effectively refuted the night vision claim for healthy individuals, though it did not address pathological conditions (retinopathy, macular degeneration).
Limitations: Review focused specifically on night vision in healthy subjects, not on visual pathology or retinal disease. Some included studies used non-standardised preparations. Older positive studies had methodological limitations. The review does not negate bilberry's potential benefits in retinal pathology.
[10]
Bilberry anthocyanosides in diabetic and hypertensive retinopathy (Perossini 1987)
Double-blind, placebo-controlled clinical trial evaluating Vaccinium myrtillus anthocyanosides (Tegens, equivalent to 115 mg anthocyanosides daily) for 1 month in patients with diabetic and/or hypertensive retinopathy.
Findings: In 14 patients with diabetic and/or hypertensive retinopathy, bilberry anthocyanosides produced significant improvement in ophthalmoscopic parameters (77% of treated patients) and fluoroangiographic parameters (90% of treated patients) compared to placebo. Results suggest bilberry anthocyanosides can improve retinal microvascular integrity in diabetic retinopathy.
Limitations: Very small sample size (n=14). Single-centre study. Published in an Italian ophthalmology journal with limited international accessibility. Methodological quality has been questioned by subsequent reviewers. Despite being widely cited, this study alone is insufficient to establish firm evidence. Requires replication in larger, multi-centre trials with current methodological standards.
[9]
Bilberry juice supplementation and cardiovascular inflammatory markers
Controlled supplementation study by Karlsen et al. (2010) in 62 subjects with at least one cardiovascular disease risk factor. Subjects received 330 mL/day bilberry juice (diluted to 1 L with water) or a control beverage for 4 weeks.
Findings: Bilberry juice supplementation produced significant decreases in plasma concentrations of inflammatory biomarkers: high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) decreased significantly compared to controls. However, no significant changes were observed in cholesterol, triglycerides, or biomarkers of antioxidant status or oxidative stress. The anti-inflammatory effects support bilberry's cardiovascular protective properties through inflammation reduction rather than direct antioxidant or lipid-modifying mechanisms.
Limitations: Moderate sample size (n=62). Short intervention period (4 weeks). Used diluted bilberry juice rather than standardised extract, making dose comparison difficult. Norwegian population. Absence of antioxidant status changes despite known in vitro antioxidant activity highlights the disconnect between in vitro and in vivo antioxidant effects.
[11]
Anthocyanin extract supplementation and lipid profiles in dyslipidaemic subjects
RCT by Qin et al. (2009) evaluating a mixed bilberry and blackcurrant anthocyanin extract (120 mg anthocyanins/day) in 60 non-diabetic dyslipidaemic subjects over 12 weeks.
Findings: Anthocyanin supplementation produced significant improvements in lipid profile: approximately 14% decrease in LDL cholesterol and approximately 14% increase in HDL cholesterol compared to placebo. No significant effects on plasma glucose levels or triglycerides. No differences in adverse effects between groups.
Limitations: Used a mixed bilberry/blackcurrant anthocyanin extract, not a pure bilberry preparation, so results cannot be attributed to bilberry alone. Relatively small sample size. Chinese study population. Non-diabetic subjects, limiting applicability to diabetic dyslipidaemia.
[12]
Pilot study of oral anthocyanins for colorectal cancer chemoprevention
First human study evaluating pharmacodynamic effects of Mirtocyan (standardised bilberry anthocyanin extract) in 25 patients with colorectal cancer. Patients received Mirtocyan at doses of 1.4, 2.8, or 5.6 g daily (supplying 0.5-2.0 g anthocyanins) for 7 days before scheduled surgery.
Findings: Anthocyanin metabolites (including methylated and glucuronidated conjugates) were identified in plasma, colorectal tissue, and urine, but not in liver. Tissue concentrations reached approximately 179 ng/g in tumor tissue at the highest dose, confirming that oral anthocyanins reach and accumulate in colorectal tissue. Tumour cell proliferation was decreased by 7% compared to pre-intervention values in all patients on Mirtocyan. However, the decrease was most pronounced at the lowest dose, with no clear dose-response relationship at higher doses.
Limitations: Pilot study with small sample size (n=25). Short intervention period (7 days). No concurrent control group (pre- vs post-intervention comparison). Lack of dose-response relationship is puzzling and limits mechanistic interpretation. The 7% proliferation decrease is modest. The study establishes bioavailability and tissue accumulation but does not demonstrate definitive anti-cancer efficacy.
[13]
Mirtoselect standardised bilberry extract in retinopathy registry study
Registry study evaluating Mirtoselect (bilberry extract standardised to 36% anthocyanins) in 140 patients with different types of retinopathy, comparing standard management alone vs. standard management plus Mirtoselect vs. standard management plus generic bilberry extract.
Findings: Mirtoselect supplementation (320 mg/day) was associated with improved retinal bioelectrical parameters. P100 amplitude and waveform on Visual Evoked Potential testing improved following 1-month supplementation in 44.4% of patients with severe preproliferative diabetic retinopathy. The study suggested that Mirtoselect represents an effective and safe integrated approach for supporting management of different retinopathies. Notably, the standardised extract outperformed generic bilberry extract, highlighting the importance of extract quality and standardisation.
Limitations: Registry study design (non-randomised, non-blinded). Heterogeneous patient population with different retinopathy types. Comparison between standardised and generic extracts may reflect dosage and quality differences. No long-term follow-up data. Results need confirmation in randomised controlled trials.
[15]
Large CVI registry study with venoactive agents including Mirtoselect
Registry study of 1,051 otherwise healthy patients with chronic venous insufficiency comparing nine venoactive products including Mirtoselect (bilberry extract) with compression stockings. Endpoints included microcirculation assessment, volume changes, and symptom evaluation.
Findings: Mirtoselect (bilberry extract, approximately 600 mg/day) demonstrated significant activity on peripheral venous microcirculation and oedema in CVI patients. Venous circulation of the retina was identified as a specific target application for Mirtoselect. No safety or tolerability problems were observed with any of the tested products across the full study population of 1,051 patients.
Limitations: Registry (observational) design without randomisation or blinding. Multiple venoactive agents compared, making attribution of effects challenging. No placebo control. The study confirms real-world effectiveness and safety but does not meet the standard of evidence of a randomised controlled trial.
Bilberry anthocyanins and AMPK-mediated insulin sensitivity in diabetic mice
Preclinical study by Takikawa et al. (2009) investigating bilberry extract supplementation (27 g/kg diet) in a mouse model of type 2 diabetes (KK-Ay mice) over 5 weeks.
Findings: Bilberry extract significantly improved insulin sensitivity, reduced fasting blood glucose, and reduced hepatic glucose output in diabetic mice. The mechanism was identified as activation of AMP-activated protein kinase (AMPK) in white adipose tissue and skeletal muscle, leading to enhanced glucose uptake via GLUT-4 transporter translocation. AMPK is a key cellular energy sensor and a therapeutic target for type 2 diabetes.
Limitations: Animal model study (KK-Ay diabetic mice). High dietary bilberry concentration (27 g/kg diet) that may not translate directly to human supplementation doses. Species differences in metabolism and bioavailability. Requires confirmation in human clinical trials.
Bilberry bioactive constituents and clinical research (comprehensive review 2022)
Comprehensive review article (Frontiers in Pharmacology, 2022) systematically evaluating the bioactive constituents and clinical research evidence for bilberry, covering antioxidant, anti-inflammatory, anti-diabetic, cardiovascular, neuroprotective, and anti-cancer properties.
Findings: Confirmed bilberry as one of the richest natural anthocyanin sources (300-700 mg/100 g fresh fruit). Documented antimicrobial activity against Salmonella, S. aureus, E. coli, and other pathogens. Reviewed evidence for anti-diabetic effects (AMPK activation, alpha-glucosidase inhibition, insulin sensitisation). Summarised cardiovascular evidence (CVI, capillary stabilisation, inflammatory marker reduction). Highlighted the importance of extract standardisation and the problem of adulteration with cheaper berry extracts in commercial products.
Limitations: Narrative review format. Includes many preclinical studies alongside limited clinical evidence. Does not provide formal evidence grading or risk-of-bias assessment. Heterogeneous study populations and preparation types limit firm conclusions.
[7]
Preparations & Dosage
Standardized Extract
Strength: Standardised to 25% anthocyanidins (or equivalently 36% anthocyanins as cyanidin-3-O-glucoside). Drug-extract ratio (DER) typically 100:1 to 200:1 (it takes 100-200 g of fresh bilberry fruit to produce 1 g of standardised extract).
Commercially prepared standardised extract of fresh bilberry fruit, produced by aqueous or hydroalcoholic extraction of fresh or fresh-frozen berries followed by concentration, purification, and spray-drying. The extract is standardised to a minimum of 25% anthocyanidins (equivalent to 36% anthocyanins expressed as cyanidin-3-O-glucoside). The two most widely researched and clinically validated standardised bilberry extracts are Myrtocyan (also called Tegens, by Inverni della Beffa/Rottapharm, Italy) and Mirtoselect (by Indena S.p.A., Italy). These extracts have been used in the majority of published clinical studies and represent the gold standard for bilberry supplementation.
80-160 mg of standardised extract (25% anthocyanidins / 36% anthocyanins) taken two to three times daily, providing a total daily intake of 160-480 mg extract (40-120 mg anthocyanidins). The most commonly studied clinical dose is 160 mg twice daily (320 mg/day total). For retinopathy: 320 mg/day. For CVI: 480-600 mg/day in some registry studies.
Two to three times daily, taken with meals
Clinical trials have used standardised extract for 4 weeks to 6 months. May be used long-term as a vascular-protective supplement. Reassess therapeutic need periodically.
Not established for standardised extracts. Not recommended for children under 12 without practitioner guidance.
Standardised extracts (particularly Myrtocyan/Mirtoselect) are the form used in the majority of clinical studies and are recommended for therapeutic applications targeting vascular protection, retinal health, and anti-inflammatory effects. The standardisation to 25% anthocyanidins ensures consistent dosing of the primary bioactive compounds. IMPORTANT: Product quality varies dramatically in the commercial bilberry supplement market. Independent testing has found that many products claiming bilberry content actually contain American blueberry (V. corymbosum) or synthetic anthocyanin dyes. Consumers and practitioners should choose products from reputable manufacturers that provide third-party verification of anthocyanin content and species authenticity (HPLC anthocyanin fingerprinting can distinguish V. myrtillus from V. corymbosum).
dried-fruit
Strength: Dried whole berries. European Pharmacopoeia requires minimum 1.0% tannins expressed as pyrogallol.
Dried ripe bilberry fruit (Myrtilli fructus siccus). The whole dried berries can be chewed directly, or prepared as a decoction: add 5-10 g (1-2 heaping teaspoons) of crushed dried bilberries to 150 mL of cold water, bring to a boil, simmer for 10-15 minutes, strain and drink. For external use as a mouthwash/gargle: prepare a stronger decoction (10% w/v, i.e., 10 g per 100 mL water) and use as a rinse after cooling to comfortable temperature.
Internal use for diarrhoea: 20-60 g dried berries daily, chewed or as decoction. A typical single dose is 5-10 g dried berries as decoction in 150 mL water, taken several times daily. External use (mouthwash/gargle): 10% decoction (10 g per 100 mL), used several times daily.
Three to four times daily for acute diarrhoea; two to three times daily for maintenance
For acute diarrhoea: use for 2-4 days. If diarrhoea persists beyond 3-4 days without improvement, seek medical advice. For mucosal inflammation (gargle): use until symptoms resolve, typically several days.
For children over 4 years: half the adult dose under parental supervision. Dried bilberry for diarrhoea in children is a well-established folk remedy.
Dried bilberry fruit is the preparation specified in the Commission E positive monograph and the EMA/HMPC traditional use monograph for dried fruit. The therapeutic action of dried bilberry is primarily ASTRINGENT (tannin-mediated), distinct from the anthocyanin-mediated vasoprotective action of fresh fruit extracts. Drying concentrates tannins while degrading the more labile anthocyanins, creating a fundamentally different therapeutic profile. For diarrhoea, the dried fruit can simply be chewed slowly (swallowing the masticated pulp) or prepared as a decoction. The decoction is also appropriate for use as a gargle or mouthwash for oropharyngeal inflammation. IMPORTANT: Fresh bilberry fruit may have a mild LAXATIVE effect due to its fibre and pectin content -- the opposite of the antidiarrhoeal dried fruit.
Tincture
Strength: 1:5, 25-45% ethanol (dried fruit). Fresh fruit tincture: 1:2, 25-30% ethanol.
Macerate dried bilberry fruit in hydroalcoholic menstruum. Standard preparation: 1:5 ratio in 25-45% ethanol. Macerate for 2-4 weeks with regular agitation. Press and filter. Alternatively, a glycerite can be prepared using vegetable glycerin in place of alcohol for alcohol-sensitive patients.
2-4 mL (40-80 drops) three times daily
Three times daily
May be used for several weeks to months. Reassess periodically.
Not recommended for children due to alcohol content. Glycerite preparation can be used: 1-2 mL three times daily for children over 4.
Tincture is a convenient preparation method, though it is not the most efficient way to deliver bilberry's therapeutic constituents. Anthocyanins are water-soluble and are well extracted by both water and dilute alcohol. Tannins are also well extracted by hydroalcoholic solvents. The tincture represents a middle ground between the dried fruit (tannin-rich) and the standardised extract (anthocyanin-rich). Clinical evidence is primarily based on standardised extracts and dried fruit rather than tinctures, so dosage equivalence with clinically studied preparations is approximate.
Decoction
Strength: 5-10 g dried fruit per 150-200 mL water (internal use); 10 g per 100 mL (external use gargle/compress)
Crush or coarsely grind dried bilberry fruit. Add 5-10 g to 150-200 mL cold water. Bring to a boil, then simmer gently for 10-15 minutes. Strain through a fine mesh. The resulting liquid is dark purple-black with an astringent, slightly sweet-tart taste. For external use (gargle, mouthwash, or compress): prepare a more concentrated decoction using 10 g per 100 mL water.
One cup (150 mL) of decoction (from 5-10 g dried berries) three to four times daily for diarrhoea. For gargle/mouthwash: use 10% decoction several times daily.
Three to four times daily for acute diarrhoea
For acute diarrhoea: 2-4 days. Seek medical advice if symptoms persist beyond 3-4 days.
For children over 4 years: half-strength decoction, 2-3 times daily
Decoction of dried bilberry fruit is the traditional European folk medicine preparation for diarrhoea and the method most closely aligned with the Commission E and ESCOP monograph usage. Boiling efficiently extracts the water-soluble tannins (proanthocyanidins) responsible for the astringent antidiarrhoeal action. The decoction is also the standard preparation for topical use as a gargle for sore throat and oral mucosal inflammation.
juice
Strength: Fresh-pressed bilberry juice; anthocyanin content varies with source but typically 200-500 mg per 100 mL undiluted juice
Fresh bilberry juice is prepared by mechanical pressing of fresh ripe berries, followed by pasteurisation for preservation. Commercial bilberry juices are available, typically from Scandinavian or Eastern European producers. The juice can be consumed undiluted or diluted with water. Freshly pressed juice should be consumed within 1-2 days if unpasteurised.
330 mL/day of undiluted bilberry juice (based on the Karlsen et al. 2010 clinical trial dosage), which can be diluted to 1 L with water for palatability. Alternatively, 100-200 mL undiluted juice daily as a general health supplement.
Once to twice daily
Can be consumed long-term as a dietary component. Clinical study used 4-week intervention.
50-100 mL daily for children over 4 years as a nutritional supplement
Bilberry juice is the preparation used in the Karlsen et al. (2010) clinical study demonstrating anti-inflammatory effects (reduced hsCRP and IL-6). Juice retains the full spectrum of fresh fruit constituents including anthocyanins, organic acids, pectins, and vitamin C. The anthocyanin dose from juice is lower and less precisely controlled compared to standardised extracts. Juice is most appropriate as a general health-promoting food or as a dietary adjunct to more targeted supplementation with standardised extracts. Note that commercial bilberry juices may be blended with other berry juices; choose products specifying 100% V. myrtillus content.
Safety & Interactions
Class 1
Can be safely consumed when used appropriately (AHPA Botanical Safety Handbook)
Contraindications
Although exceedingly rare, any individual with confirmed allergy to bilberry, blueberry, cranberry, or other Vaccinium species should avoid bilberry preparations. No cases of severe allergic reaction (anaphylaxis) to bilberry have been reported in the literature, but standard precautions apply.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Warfarin, heparin, and other anticoagulants (Anticoagulants) | moderate | Bilberry anthocyanins have demonstrated in vitro inhibition of platelet aggregation and may potentiate anticoagulant effects. One published case report described rectal bleeding and haematuria in a 77-year-old patient taking bilberry concurrently with anticoagulant/antiplatelet medications. |
| Aspirin, clopidogrel, NSAIDs, and other antiplatelet agents (Antiplatelet agents) | moderate | Bilberry may have synergistic effects with aspirin on platelet aggregation inhibition, potentially increasing the risk of bleeding. The case report of bleeding involved a patient with a cardiovascular history (likely on antiplatelet therapy). |
| Insulin, metformin, sulfonylureas, and other antidiabetic medications (Hypoglycaemic agents) | theoretical | Bilberry anthocyanins demonstrate mild hypoglycaemic activity through AMPK activation, alpha-glucosidase inhibition, and enhancement of insulin sensitivity. Additive blood glucose-lowering effects are theoretically possible when combined with pharmaceutical antidiabetic agents, though this has not been demonstrated in clinical studies at typical supplement doses. |
| CYP450 substrates (general) (Various medications metabolised by cytochrome P450 enzymes) | theoretical | Some in vitro studies suggest bilberry anthocyanins may modulate cytochrome P450 enzyme activity (particularly CYP3A4 and CYP2C9). However, the clinical significance of these in vitro findings is uncertain given the low systemic bioavailability of anthocyanins (approximately 1-2%). |
Pregnancy & Lactation
Pregnancy
likely safe
Lactation
insufficient data
Bilberry fruit has been consumed as a food throughout Europe for centuries, including during pregnancy, with no reported adverse effects. The fruit in food amounts is generally considered safe during pregnancy. Bilberry has been specifically reported as safe and efficacious for the treatment of gestational haemorrhoids and venous insufficiency of pregnancy. However, concentrated bilberry extract supplements at therapeutic doses have not been formally studied in controlled pregnancy trials. The American Herbal Products Association classifies bilberry fruit as Class 1 (safe when used appropriately), without specific pregnancy restrictions for the fruit. As a precautionary measure, therapeutic doses of concentrated bilberry extract should be used during pregnancy only under the guidance of a qualified healthcare provider. Bilberry fruit in dietary/food amounts is likely safe. Regarding lactation, there is insufficient data on the passage of bilberry anthocyanins into breast milk. Given the long history of bilberry consumption as food in Northern Europe, dietary amounts during breastfeeding are likely safe, but concentrated therapeutic doses have not been studied.
Adverse Effects
References
Monograph Sources
- [1] German Federal Institute for Drugs and Medical Devices (BfArM), Commission E. Commission E Monograph: Myrtilli fructus (Bilberry fruit, dried). Bundesanzeiger (Federal Gazette), Germany (1986)
- [2] European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Vaccinium myrtillus L., fructus recens; and European Union herbal monograph on Vaccinium myrtillus L., fructus siccus. EMA/HMPC/159076/2013 (fresh fruit); EMA/HMPC/678995/2013 (dried fruit). London: EMA (2015)
- [3] European Scientific Cooperative on Phytotherapy (ESCOP). ESCOP Monographs: Myrtilli fructus (Bilberry Fruit). ESCOP Monographs, 2nd edition. Stuttgart: Georg Thieme Verlag (2003)
- [4] Ulbricht C, Basch E, et al.. Vaccinium myrtillus (Bilberry) Monograph. Alternative Medicine Review (2001) ; 6 : 500-515 . PMID: 11703171
- [5] Chu W-K, Cheung SCM, Lau RAW, Benzie IFF. Bilberry (Vaccinium myrtillus L.). In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis (2011)
- [6] British Herbal Medicine Association. British Herbal Pharmacopoeia: Myrtilli fructus. British Herbal Medicine Association, Bournemouth (1983)
- [7] Zhong H, Xue Y, Lu X, Shao Q, Cao Y, Wu Z, Chen G. Bilberries: Curative and Miraculous -- A Review on Bioactive Constituents and Clinical Research. Frontiers in Pharmacology (2022) ; 13 : 909914 . DOI: 10.3389/fphar.2022.909914
- [8] National Institute of Diabetes and Digestive and Kidney Diseases. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury -- Bilberry. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases (2012)
Clinical Studies
- [9] Perossini M, Guidi G, Chiellini S, Siravo D. 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
- [10] Canter PH, Ernst E. Anthocyanosides of Vaccinium myrtillus (bilberry) for night vision -- a systematic review of placebo-controlled trials. Survey of Ophthalmology (2004) ; 49 : 38-50 . DOI: 10.1016/j.survophthal.2003.10.006 . PMID: 14711439
- [11] Karlsen A, Paur I, Bohn SK, Sakhi AK, Borge GI, Serafini M, Erlund I, Laake P, Tonstad S, Blomhoff R. Bilberry juice modulates plasma concentration of NF-kappaB related inflammatory markers in subjects at increased risk of CVD. European Journal of Nutrition (2010) ; 49 : 345-355 . DOI: 10.1007/s00394-010-0092-0 . PMID: 20119859
- [12] Qin Y, Xia M, Ma J, Hao Y, Liu J, Mou H, Cao L, Ling W. Anthocyanin supplementation improves serum LDL- and HDL-cholesterol concentrations associated with the inhibition of cholesteryl ester transfer protein in dyslipidemic subjects. American Journal of Clinical Nutrition (2009) ; 90 : 485-492 . DOI: 10.3945/ajcn.2009.27814 . PMID: 19640950
- [13] Thomasset S, Berry DP, Cai H, West K, Marczylo TH, Marsden D, Brown K, Dennison A, Garber G, Steward WP, Gescher AJ. Pilot study of oral anthocyanins for colorectal cancer chemoprevention. Cancer Prevention Research (2009) ; 2 : 625-633 . DOI: 10.1158/1940-6207.CAPR-08-0201 . PMID: 19584076
- [14] Shim SH, Kim JM, Choi CY, Kim CY, Park KH. Ginkgo biloba extract and bilberry anthocyanins improve visual function in patients with normal tension glaucoma. Journal of Medicinal Food (2012) ; 15 : 818-823 . DOI: 10.1089/jmf.2012.2241 . PMID: 22870951
- [15] Forte R, Cennamo G, Finelli ML, Bonavolonta P, de Crecchio G, Greco GM. The effect of oral supplementation with standardized bilberry extract (Mirtoselect) on retino-cortical bioelectrical activity in severe diabetic retinopathy. Minerva Oftalmologica (2017) ; 59 : 38-41
- [16] Martineau LC, Couture A, Spoor D, Benhaddou-Andaloussi A, Harris C, Meddah B, Leduc C, Burt A, Vuong T, Mai Le P, Prentki M, Bennett SA, Arnason JT, Haddad PS. Anti-diabetic properties of the Canadian lowbush blueberry Vaccinium angustifolium Ait.. Phytomedicine (2006) ; 13 : 612-623 . DOI: 10.1016/j.phymed.2006.08.005 . PMID: 16979328
- [17] Belcaro G, Dugall M, Luzzi R, Hosoi M, Corsi M. Management of varicose veins and chronic venous insufficiency in a comparative registry with nine venoactive products in comparison with stockings. International Journal of Angiology (2017) ; 26 : 170-178 . DOI: 10.1055/s-0036-1586173 . PMID: 28894379
Traditional Texts
- [18] Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Rochester, VT: Healing Arts Press (2003)
- [19] Bone K, Mills S. Principles and Practice of Phytotherapy: Modern Herbal Medicine, 2nd edition. Edinburgh: Churchill Livingstone/Elsevier (2013)
Pharmacopeias & Reviews
- [20] European Directorate for the Quality of Medicines (EDQM). European Pharmacopoeia, 11th edition: Myrtilli fructus recens (Bilberry fruit, fresh); Myrtilli fructus siccus (Bilberry fruit, dried); Bilberry fruit dry extract, refined and standardised. Council of Europe, Strasbourg (2023)
Last updated: 2026-03-02 | Status: review
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