Bilberry Extract: Benefits, Forms, Dosing, and Side Effects

Bilberry (Vaccinium myrtillus), often called European blueberry, is a dark-skinned berry native to northern Europe with a nutritional profile distinct from the North American blueberries found in most supermarkets. Its flesh is characteristically purple — not light green — and it contains a substantially higher concentration of anthocyanins, the water-soluble pigments responsible for its deep colour. These compounds have attracted research interest for retinal health, blood vessel integrity, metabolic function, and anti-inflammatory effects. The overall clinical evidence ranges from moderately supportive (retinopathy, dry eye, some metabolic markers) to clearly unsupported (night vision enhancement in healthy individuals).

Table of Contents

• Overview
• Nutritional Profile
• Forms and Bioavailability
• Evidence for Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Overview

Bilberry (Vaccinium myrtillus L.) is a low-growing deciduous shrub in the family Ericaceae, native to northern Europe, northern Asia, and parts of North America [1][2]. While its outer skin is dark blue or purple like a blueberry, bilberry flesh is characteristically purple rather than light green, reflecting a substantially different polyphenol profile [3][4].

Fresh bilberries contain 300–700 mg of anthocyanins per 100 g of fresh fruit — roughly 2–4 times the concentration found in cultivated blueberries [1][2][5]. The predominant anthocyanins include glycosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin [1][5][6]. Additional bioactive compounds include quercetin (~3 mg per 100 g), catechin (~20 mg per 100 g), tannins, phenolic acids, and vitamin C (3–33 mg per 100 g depending on growing conditions) [1][2].

The medicinal use of bilberry dates to antiquity. The ancient Greek physician Dioscorides documented bilberry fruits for treating diarrhea and dysentery in the 1st century AD, leveraging the astringent properties of tannins [7]. By the 16th century, bilberry was commonly used for diarrhea, urinary tract conditions, scurvy, and biliary disorders [7][8]. In traditional European and Russian folk medicine, bilberry leaf teas were among the most popular herbal remedies for managing blood sugar in diabetes [1][7].

The most famous — and most contested — claim about bilberry concerns night vision. During World War II, British Royal Air Force pilots reportedly ate bilberry jam before night missions, claiming it improved their night vision [3][9]. However, this story may have been a deliberate rumour intended to conceal the British military's use of radar technology, which the Germans did not possess [10][11]. Regardless of origin, this wartime legend prompted decades of research into bilberry's effects on vision. Today, the NCCIH states that bilberry "has not been clearly shown to be helpful for any health condition," though some preliminary research on retinal health exists [9].

Today, bilberry extract supplements are marketed primarily for eye health, cardiovascular support, blood sugar management, and antioxidant protection. This article reviews the full spectrum of evidence.

Nutritional Profile

Bilberry fruit is a nutrient-dense, low-calorie food [1][2]:

Nutrient	Per 100 g Fresh Fruit	Notes
Energy	~57 kcal	Low-calorie profile
Protein	0.7 g
Carbohydrates	12 g (sugars: ~6 g)
Dietary Fiber	2.5 g	Supports digestive health
Fat	<0.5 g
Vitamin C	3–33 mg	Varies by growing conditions and region
Vitamin E	1.9–2.1 mg
Anthocyanins	300–700 mg	Delphinidin and cyanidin glycosides predominant
Quercetin	~3 mg
Catechin	~20 mg

Forms and Bioavailability

Standardized Extracts

The vast majority of clinical research on bilberry has been conducted with concentrated extracts, not the whole berry. The key extract to understand is Myrtocyan (also marketed as Tegens or MirtoSelect), a standardized bilberry extract containing approximately 36% anthocyanosides [3][4][13].

This standardization is critical. Fresh bilberry contains only 0.3–0.7% anthocyanosides [14]. The Myrtocyan/MirtoSelect extract is concentrated approximately 100-fold — the ratio of starting material to powdered extract ranges from 76:1 to 153:1 according to the United States Pharmacopeia (USP 36) [3]. This means that 100 mg of standardized extract delivers approximately 36 mg of anthocyanosides, equivalent to the anthocyanosides in roughly 5–12 grams of fresh fruit.

Understanding Label Claims

Supplement labels can be confusing because manufacturers use different analytical methods [3][4]:

Label Claim	What It Means	Equivalence
36% anthocyanosides	Measures the full anthocyanoside molecule (anthocyanidin + attached sugar)	Standard reference measure
25% anthocyanidins	Measures only the anthocyanidin portion (without sugar moiety)	Equivalent to 36% anthocyanosides
25% anthocyanosides	A less concentrated extract	~70% of the potency of 36% anthcyanoside extracts

Products claiming "25% anthocyanidins" are equivalent to those claiming "36% anthocyanosides" because the analytical method excludes the weight of naturally attached sugars. However, products claiming "25% anthocyanosides" are genuinely less concentrated [3].

Some bilberry products list concentration ratios as low as 4:1, which would provide only a few milligrams of anthocyanosides per serving — far below the doses used in clinical trials [3]. For reference:

• Clinical-grade extract (76:1 to 153:1): ~36% anthocyanosides. Used in virtually all positive clinical trials.
• Moderate concentration (10:1 to 50:1): Variable anthcyanoside content. May or may not replicate clinical trial effects.
• Low concentration (4:1 to 10:1): Very low anthcyanoside content. Unlikely to provide therapeutic doses.

Anthocyanin Bioavailability

Anthocyanins are generally poorly bioavailable compared to many other polyphenols. Peak plasma concentrations after oral consumption are typically reached within 1–2 hours, with most anthocyanins cleared from the bloodstream within 6–8 hours [5][15]. Several factors influence absorption:

Absorption: Anthocyanins are absorbed primarily in the stomach and small intestine. Unlike most polyphenols that require hydrolysis before absorption, intact anthocyanin glycosides can be absorbed directly via the bilitranslocase transporter in gastric mucosa [15][16].

Metabolism: Once absorbed, anthocyanins undergo extensive phase I and phase II metabolism in the liver, yielding methylated, glucuronidated, and sulfated metabolites. These metabolites retain some biological activity but differ in potency from the parent compounds [15].

Gut microbiome: A significant proportion of ingested anthocyanins (~80–90%) reaches the colon unabsorbed, where gut bacteria degrade them into phenolic acids (protocatechuic acid, gallic acid, syringic acid). These microbial metabolites may account for a substantial portion of the observed health effects attributed to anthocyanin consumption, as they have longer half-lives and higher bioavailability than intact anthocyanins [15][16].

Matrix effects: Consuming bilberry with food, particularly fat-containing meals, may slow gastric emptying and improve anthocyanin stability at gastric pH, though the net effect on bioavailability is debated [15].

Forms Available as Supplements

Form	Description	Key Considerations
Standardized extract (36% anthcyanosides)	Myrtocyan/MirtoSelect or equivalent	Gold standard for clinical research. Most evidence applies to this form.
Standardized extract (25% anthcyanidins)	Alternative analytical standard	Equivalent potency to 36% anthcyanoside extracts
Non-standardized extract	Variable concentration	Unpredictable anthcyanoside content; difficult to match clinical doses
Whole berry powder	Dried, ground bilberry fruit	Very low anthcyanoside concentration (0.3–0.7%); large doses needed to match extract trials
Bilberry leaf extract	Extract from V. myrtillus leaves	Different compound profile (more tannins, less anthcyanin). Animal data on blood sugar; limited human evidence. Safety concerns with long-term use [3][9]
Bilberry juice	Pressed juice from fresh berries	Retains anthcyanins but at whole-fruit concentrations. Not a clinical intervention equivalent
Fermented bilberry extract	Fermented with lactic acid bacteria	Emerging research on skin health and bioavailability enhancement [17]

Species Confusion

Check labels carefully: the Supplement Facts panel should specify Vaccinium myrtillus [3]. Some products use "American bilberry" (actually huckleberry, Vaccinium membranaceum) or other Vaccinium species that have different anthcyanin profiles and concentrations. One review identified a product with "Bilberry" prominently displayed on the label that was actually huckleberry — confirmed only by reading the Supplement Facts panel [3].

Evidence for Benefits

Retinopathy (Diabetic and Hypertensive)

The strongest clinical evidence for bilberry relates to retinal damage caused by diabetes or hypertension.

Pivotal trial: A double-blind, placebo-controlled trial of bilberry extract (Myrtocyan) in patients with diabetic retinopathy or hypertensive retinopathy found significant improvements in retinal lesions (Perossini et al., Ann Ottalmol Clin Ocul, 1987) [18][3]. Patients received bilberry extract providing 115 mg of anthocyanosides daily. Ophthalmoscopic examination showed reduced retinal haemorrhages and improved vascular integrity in the treatment group compared to placebo.

Supporting evidence: Additional studies, though not all double-blind, have indicated benefits for retinal health. The proposed mechanism involves anthocyanosides strengthening capillary walls in the retina, reducing permeability and fragility of retinal microvessels [3][4][19]. Anthcyanins may also protect retinal pigment epithelial cells from oxidative damage and reduce pathological neovascularisation [19].

Mechanistic basis: The retina is one of the most metabolically active tissues in the body with high oxygen consumption, making it particularly vulnerable to oxidative stress. Bilberry anthcyanins have demonstrated photoprotective effects on retinal cells in vitro, inhibiting light-induced apoptosis and reducing reactive oxygen species generation [19][20].

Night Vision

This is bilberry's most famous claim — and the one with the weakest evidence in healthy individuals.

Canter and Ernst (2004) conducted a systematic review of all placebo-controlled clinical trials of bilberry and night vision. The results were mixed: some studies showed short-term improvements (lasting approximately 2 hours), while the most rigorously designed studies showed no benefit. The reviewers concluded that the evidence does not convincingly support bilberry for long-term improvement of night vision in healthy individuals [11][3]. Clinical studies through the 2020s have similarly shown limited or no benefits for normal night vision in healthy individuals [21].

At best, bilberry may provide a transient (~2 hour) modest improvement in some aspects of night vision at higher doses (providing at least 60 mg anthcyanosides), but there is no evidence for sustained night vision enhancement. The widespread marketing of bilberry for night vision exceeds the clinical evidence [3][11][21].

Dry Eye Syndrome

More recent research has examined bilberry for dry eye, with more promising results than the night vision data.

A randomised, double-blind, placebo-controlled trial demonstrated that a standardised bilberry extract (MirtoSelect) improved tear film stability and reduced ocular discomfort in patients with dry eye syndrome after 12 weeks of supplementation [21][22]. The mechanism may involve anti-inflammatory effects on the lacrimal gland and meibomian glands, as well as antioxidant protection of the tear film lipid layer.

A 2022 meta-analysis on interventions for computer vision syndrome (which often includes dry eye) reported mixed outcomes: modest reductions in symptoms like eye fatigue were observed, but there was no consistent effect on tear production scores as measured by the Schirmer test [21].

Metabolic Health: Blood Sugar and Insulin Sensitivity

Animal and preliminary human evidence suggests bilberry may benefit metabolic parameters, though the evidence is early-stage.

In traditional European and Russian folk medicine, bilberry leaf tea was one of the most popular herbal treatments for diabetes management [1][7]. Modern animal studies suggest that bilberry leaves may help improve blood sugar control and lower blood triglycerides [3].

In human evidence, a crossover study showed reduced postprandial blood glucose levels after 12 weeks of supplementation at 160 mg/day of anthcyanins [12][23]. A study by Hoggard et al. found that a bilberry-enriched diet for 8 weeks improved markers of insulin sensitivity and inflammation in overweight and obese individuals (Hoggard et al., J Nutr Sci, 2013) [24][25]. A 2025 meta-analysis indicated potential benefits for lipid profiles and glycaemic indices in metabolic health, though the included trials were generally small and short-term [26].

Anthcyanins appear to modulate glucose metabolism through multiple pathways: enhancing insulin signalling via AMPK activation, inhibiting intestinal alpha-glucosidase (slowing carbohydrate digestion), reducing hepatic glucose output, and protecting pancreatic beta-cells from oxidative damage [12][23][24].

Bilberry leaf vs. fruit: It is important to distinguish between bilberry fruit extract and bilberry leaf extract. The animal evidence for blood sugar reduction relates primarily to bilberry leaves, which contain different bioactive compounds (more tannins and catechins, fewer anthcyanins) than the fruit [3][9]. Bilberry leaf safety for long-term use in humans is not well established.

Cardiovascular and Vascular Health

Blood Vessel Integrity and Chronic Venous Insufficiency

Bilberry anthcyanosides have been traditionally used for vascular conditions based on their ability to strengthen blood vessel walls.

Anthcyanosides resemble the oligomeric proanthocyanidin complexes (OPCs) found in grape seed and pine bark. Like OPCs, bilberry anthcyanosides have been shown to stabilise collagen-containing tissues (tendons, ligaments, cartilage), reduce capillary permeability and fragility, and inhibit platelet aggregation (Jonadet et al., J Pharm Belg, 1983; Chu, 2011) [3][4][27].

A 2022 systematic analysis of clinical data indicated that anthcyanin-rich bilberry extracts reduced symptoms of chronic venous insufficiency, including leg swelling and pain, possibly through strengthened capillary walls. Effects were more pronounced in combination therapies [12].

Based on the similarity of bilberry anthcyanosides to grape seed OPCs, bilberry has been suggested for varicose veins, easy bruising, and support after minor surgery. However, there is currently insufficient evidence from well-designed trials to firmly support these uses [3][4].

Lipid Profiles

Short-term supplementation trials in 2025 showed that bilberry extract reduced atherogenic small dense LDL subfractions — a particularly harmful form of LDL cholesterol associated with increased cardiovascular risk [28]. Animal studies suggest bilberry (particularly bilberry leaf) may lower blood triglycerides [3]; a 2025 meta-analysis also showed potential lipid profile benefits in human studies [26].

Platelet Aggregation

Bilberry extract (equivalent to 173 mg anthcyanins per day) taken for one to two months has been shown to inhibit platelet aggregation in healthy adults (Pulliero et al., Fitoterapia, 1989) [29]. This antiplatelet effect may contribute to cardiovascular protection but also raises potential bleeding concerns (see Safety section).

Anti-Inflammatory and Antioxidant Effects

Bilberry anthcyanins have consistently demonstrated strong antioxidant activity in laboratory models, scavenging free radicals and inhibiting oxidative stress in cellular systems [1][12]. The ORAC (Oxygen Radical Absorbance Capacity) values for bilberry are among the highest of any commonly consumed berry [5].

Anthcyanosides also stabilise tissues containing collagen — including tendons, ligaments, and cartilage — by cross-linking collagen fibres and inhibiting collagen-degrading enzymes (Jonadet et al., J Pharm Belg, 1983; Chu, 2011) [3][27]. Preclinical studies suggest bilberry anthcyanins downregulate NF-kB signalling, reduce COX-2 expression, and inhibit production of pro-inflammatory cytokines including IL-6, TNF-alpha, and IL-1beta [12][19].

While the in vitro and animal data are robust, translating antioxidant capacity measured in test tubes to meaningful clinical outcomes in humans remains a challenge for bilberry research, as it does for all antioxidant-rich foods and supplements.

Kidney Health

Studies in 2024–2025 reported protective effects of bilberry extract against diabetic nephropathy in animal models, likely mediated by reduced oxidative stress and inflammation in renal tissue [30]. Human data for this indication are not yet available.

Skin Health

Studies in 2024–2025 showed that fermented bilberry extract improved skin ageing parameters and complexion evenness [17]. The fermentation process may enhance bioavailability of certain bilberry polyphenols while generating novel bioactive metabolites. In vitro studies suggest bilberry anthcyanins may also protect skin cells from UV-induced damage through antioxidant mechanisms, though clinical trials are needed [19].

Mood and Cognitive Function

A 2025 pilot study found that bilberry extract supplementation improved mood parameters, specifically reducing tension and depression scores on validated scales [31]. The study was small and preliminary. Epidemiological data suggest that anthcyanin-rich diets are associated with slower cognitive decline, but bilberry-specific cognitive trials in humans are scarce. The mechanistic rationale involves anthcyanin-mediated improvements in cerebrovascular blood flow and neuroprotection via reduced neuroinflammation [12][15].

Other Traditional and Proposed Uses

Based on structural similarity to grape seed and pine bark OPCs, bilberry has been suggested for several additional conditions. However, the evidence is currently insufficient to support these uses [3][4]:

• Easy bruising: Theoretical basis from capillary-strengthening effects, but no clinical trials specific to bilberry
• Varicose veins: Limited human data; some support from chronic venous insufficiency studies
• Diarrhea: Traditional use supported by the tannin content of bilberry fruit (astringent properties), but no modern clinical trials
• Mouth ulcers and skin irritations: Traditional topical application leveraging tannin-mediated anti-inflammatory effects [7][8]

Recommended Dosing

Clinical Trial Doses

Most positive clinical studies have used highly concentrated bilberry extracts standardised to 36% anthcyanosides (or the equivalent 25% anthcyanidins) [3][4]:

Indication	Daily Dose	Anthcyanoside Content	Duration	Evidence Level
Retinopathy (diabetic/hypertensive)	~320 mg extract	115 mg anthcyanosides	1–6 months	Moderate (double-blind RCT)
Night vision (acute effect)	Variable	60–300+ mg anthcyanosides	Single dose (2 hr effect)	Weak (inconsistent results)
Dry eye syndrome	160 mg extract (MirtoSelect)	~57 mg anthcyanosides	12 weeks	Moderate (double-blind RCT)
Metabolic health (blood sugar)	160 mg anthcyanins/day	~160 mg anthcyanins	8–12 weeks	Preliminary
General antioxidant	160–480 mg extract	57–173 mg anthcyanosides	Varies	Low (mostly in vitro)
Platelet aggregation inhibition	~480 mg extract	173 mg anthcyanins	1–2 months	Moderate (single study)

Standard Dosing Recommendations

For bilberry extract standardised to 36% anthcyanosides:

• General supplementation: 80–160 mg, taken 1–2 times daily [3][4]
• Retinopathy support: 160 mg twice daily (providing ~115 mg total anthcyanosides) [18][3]
• Dry eye/ocular health: 160 mg once daily [22]
• Cardiovascular/vascular support: 160–240 mg twice daily [3][29]

Timing and Administration

• Bilberry extract can be taken with or without food. Taking with a meal may improve tolerance and potentially enhance absorption due to slowed gastric emptying [15].
• For acute effects on vision (if attempting short-term benefit), bilberry was typically taken 1–2 hours before the desired effect in studies showing any benefit [11].
• For chronic conditions (retinopathy, metabolic health, vascular health), consistent daily use for at least 4–12 weeks is needed before benefits would be expected.

How to Read a Bilberry Supplement Label

The most important factors to verify on a bilberry supplement label:

1. Species: Confirm Vaccinium myrtillus (not huckleberry, blueberry, or other species)
2. Standardisation: Look for "36% anthcyanosides" or "25% anthcyanidins" — these are equivalent and represent clinical-grade concentration
3. Extract ratio: High ratios (76:1 to 153:1) indicate properly concentrated extracts. Low ratios (4:1 to 10:1) indicate minimal concentration
4. Dose per serving: Calculate anthcyanoside content: dose (mg) × standardisation percentage = anthcyanosides per serving. For example, 160 mg of 36% extract = 57.6 mg anthcyanosides
5. Branded ingredient: Products listing MirtoSelect or Myrtocyan specifically use the extract studied in clinical trials [3]

Safety and Side Effects

Bilberry fruit is a food consumed throughout Europe and is considered quite safe [3][9]. The NCCIH states that bilberry fruit extracts have been used safely in research studies at doses of up to 160 mg/day for up to 6 months and appear to be well tolerated [9]. A broader assessment suggests bilberry is generally safe for short-term use at doses up to 480 mg/day of extract [12].

Reported Side Effects

Side effects from bilberry extract supplementation are uncommon but may include [3][32]:

• Gastrointestinal: A small percentage of people may experience mild digestive distress, including nausea, stomach discomfort, or diarrhea
• Skin reactions: Rare reports of skin rashes
• Drowsiness: Reported in at least one clinical study (Eandi, Fitoterapia, 1996) [32]
• Allergic reactions: Very rare; primarily in individuals with sensitivity to Ericaceae family plants

Blood Sugar Effects

Bilberry extract may lower blood sugar and increase insulin sensitivity (Stull, Antioxidants (Basel), 2016; Hoggard et al., J Nutr Sci, 2013) [24][25]. While potentially beneficial for people with insulin resistance, this effect poses a risk for:

• Individuals with hypoglycaemia or those prone to low blood sugar
• People taking diabetes medications (insulin, metformin, sulfonylureas, etc.) — bilberry may potentiate their blood sugar-lowering effects
• People taking other supplements that lower blood sugar

Anyone with diabetes, hypoglycaemia, or using blood sugar-lowering medications should consult a physician before taking bilberry extract [3][9].

Antiplatelet Effects

Bilberry extract (equivalent to 173 mg anthcyanins per day) has been shown to inhibit platelet aggregation in healthy adults after 1–2 months of use (Pulliero et al., Fitoterapia, 1989) [29]. While no published reports document bilberry extract causing clinical bleeding or interacting with blood-thinning medications such as warfarin, the theoretical risk exists [3][9][12].

Surgery

Due to the potential for bilberry extract to affect both blood sugar levels and platelet aggregation, stopping bilberry supplements at least two weeks before any scheduled surgery is recommended [3].

Bilberry Leaf Safety

Bilberry leaf safety is less established than bilberry fruit/extract safety [3][9]:

• Long-term use: Bilberry leaves may be unsafe when consumed in high doses or for long periods of time [9]
• Blood sugar: Based on animal evidence that bilberry leaf can reduce blood sugar, people with diabetes using bilberry leaf may need medication dose adjustments (Cignarella et al., Thromb Res, 1996) [33]
• Lack of human data: Unlike bilberry fruit extract, bilberry leaf extract has not been evaluated in rigorous human safety studies

Special Populations

• Pregnancy and breastfeeding: Little is known about the safety of bilberry supplementation in amounts greater than those found in food during pregnancy or while breastfeeding. Bilberry fruit consumed as food is considered safe [3][9].
• Children: Safety in young children has not been established [3].
• Severe liver or kidney disease: Safety is not known for these populations [3].

Drug Interactions

Anticoagulant and Antiplatelet Medications

Bilberry's demonstrated antiplatelet activity [29] creates a theoretical interaction with blood-thinning medications [3][9][12]:

Drug Class	Examples	Concern	Recommendation
Vitamin K antagonists	Warfarin (Coumadin)	Theoretical increased bleeding risk	Consult physician before use
Direct oral anticoagulants	Apixaban, rivaroxaban, dabigatran	Theoretical increased bleeding risk	Consult physician before use
Antiplatelet drugs	Aspirin, clopidogrel	Additive antiplatelet effect	Consult physician before use
NSAIDs	Ibuprofen, naproxen	Combined effect on bleeding	Use with caution

While no published case reports document bilberry-anticoagulant interactions, the documented inhibition of platelet aggregation warrants caution [3][29].

Blood Sugar-Lowering Medications

Bilberry's effects on blood sugar and insulin sensitivity may interact with diabetes medications [3][24][25]:

Drug Class	Examples	Concern	Recommendation
Insulin	All forms	Additive blood sugar lowering	Monitor blood glucose closely
Sulfonylureas	Glipizide, glyburide	Additive blood sugar lowering	Monitor blood glucose closely
Metformin	Glucophage	Possible additive effect	Monitor blood glucose
SGLT2 inhibitors	Empagliflozin, dapagliflozin	Possible additive effect	Monitor blood glucose
GLP-1 agonists	Semaglutide, liraglutide	Possible additive effect	Monitor blood glucose
Other hypoglycaemic herbs/supplements	Berberine, cinnamon, fenugreek	Additive blood sugar lowering	Use with caution

Other Potential Interactions

• Cytochrome P450 substrates: Some in vitro evidence suggests anthcyanins may modulate CYP enzyme activity, potentially affecting the metabolism of drugs processed by these enzymes. Clinical significance in humans at typical supplement doses is unclear [12][15].
• Iron absorption: Tannins in bilberry may theoretically reduce iron absorption if taken simultaneously. Separating bilberry supplements from iron supplements by 2 hours is a reasonable precaution, though this interaction has not been specifically documented for bilberry extract [15].

Dietary Sources

Fresh Bilberries vs. Blueberries

Bilberry grows wild across northern Europe, northern Asia, and parts of North America, thriving in acidic, moist soils in nutrient-poor forest understories at elevations from near sea level to over 3,000 m [1][2]. The peak harvesting season is late summer (July through September).

Fresh bilberries differ from cultivated blueberries in several important ways [1][2][3]:

Characteristic	Bilberry (V. myrtillus)	Blueberry (V. corymbosum)
Flesh colour	Purple/dark red throughout	Light green/white
Anthocyanin content (per 100 g)	300–700 mg	80–250 mg
Size	5–12 mm diameter	10–20 mm diameter
Cultivation	Primarily wild-harvested	Extensively cultivated
Availability	Seasonal, mainly Europe	Year-round, global
Flavour	More intense, tart	Sweeter, milder

Blueberries (Vaccinium corymbosum) are a related species with a different anthcyanin profile and are not interchangeable with bilberry in clinical contexts.

Wild Harvesting and Availability

Bilberries are primarily wild-harvested rather than cultivated. Major harvesting regions include Scandinavia (particularly Sweden and Finland), Russia, and Poland [1][34]. Commercial cultivation remains limited due to bilberry's slow growth, low per-plant yields (often under 1 kg per mature bush annually), and requirement for specific soil conditions (pH 3.8–5.5) and mycorrhizal associations [1][2][34].

In Sweden alone, the potential annual yield of bilberries and lingonberries combined exceeds 800,000 tons, though only about 2–5% is commercially harvested [34]. This limited commercial availability contributes to higher costs for bilberry products compared to blueberry equivalents.

Food Forms

Bilberries are consumed in various culinary forms throughout Europe [1]:

• Fresh: Tart when eaten raw; often preferred cooked or in combination with sweeter foods
• Jams and preserves: Traditional preparation method that preserves seasonal abundance. The high anthcyanin content produces deep purple spreads.
• Pies and tarts: A staple dessert in Nordic cuisine (e.g., Finnish mustikkapiirakka)
• Blåbärssoppa: A traditional Scandinavian bilberry soup, served warm or chilled, thickened with potato starch
• Juices: Retain the deep purple colour and sharp taste; often diluted or sweetened
• Dried berries: Used for herbal teas or as a snack
• Frozen: Maintains nutrient content well; the most common commercial form outside harvesting regions

How Processing Affects Anthocyanin Content

Anthcyanins are sensitive to heat, light, pH, and oxygen. Processing bilberries reduces their anthcyanin content to varying degrees [5][15]:

• Freezing: Minimal loss; preserves most anthcyanins
• Drying: Moderate loss (10–30%) depending on temperature and method
• Cooking/jam-making: Variable loss (20–50%) depending on temperature and duration
• Juicing: Retains most water-soluble anthcyanins but loses fibre and some bound polyphenols
• Fermentation: May actually increase bioavailability of certain compounds while reducing total anthcyanin content

Comparison with Other Anthocyanin-Rich Foods

Bilberry is among the richest dietary sources of anthcyanins, but other foods also contribute meaningful amounts [5][15]:

Food	Anthocyanins (mg per 100 g)
Bilberry (V. myrtillus)	300–700
Black elderberry	400–1,400
Black chokeberry (aronia)	300–2,000
Blackcurrant	130–400
Black raspberry	200–400
Cultivated blueberry	80–250
Red cabbage	25–100
Eggplant (skin)	30–85
Red grape	30–80
Cherry	10–80

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20. Retinal cell photoprotection studies. As cited in Vaneková Z, Rollinger JM. Frontiers in Pharmacology. 2022;13:909914.
21. Vision studies 2004–2020s. As reviewed in Grokipedia and ConsumerLab. Includes: systematic reviews of placebo-controlled trials, RCTs on computer vision syndrome (2022 meta-analysis), and dry eye supplementation trials.
22. MirtoSelect dry eye trial. Randomised, double-blind, placebo-controlled trial of standardised bilberry extract for dry eye syndrome. As cited in Grokipedia and Vaneková Z, Rollinger JM. Frontiers in Pharmacology. 2022;13:909914.
23. Bilberry and glycaemic control: small-scale crossover study of bilberry extract at 160 mg/day anthcyanins for 12 weeks. As reviewed in Chan SW, Tomlinson B. Molecules. 2020;25(7):1653.
24. Stull AJ. "Blueberries' impact on insulin resistance and glucose intolerance." Antioxidants (Basel). 2016;5(4):44. https://doi.org/10.3390/antiox5040044
25. Hoggard N, Cruickshank M, Moar KM, et al. "A single supplement of a standardised bilberry (Vaccinium myrtillus L.) extract (36% wet weight anthcyanins) modifies glycaemic response in individuals with type 2 diabetes controlled by diet and lifestyle." Journal of Nutritional Science. 2013;2:e22. https://doi.org/10.1017/jns.2013.16
26. 2025 meta-analysis of bilberry effects on lipid profiles and glycaemic indices. As reported in Grokipedia.
27. Jonadet M, Meunier MT, Villie F, et al. "Flavonoids extracted from Ribes nigrum L. and Alchemilla vulgaris L." Journal de Pharmacie de Belgique. 1983;41(3):159–167.
28. 2025 short-term supplementation trials showing reductions in atherogenic small dense LDL subfractions. As reported in Grokipedia.
29. Pulliero G, Montin S, Bettini V, et al. "Ex vivo study of the inhibitory effects of Vaccinium myrtillus anthcyanosides on human platelet aggregation." Fitoterapia. 1989;60(1):69–75.
30. Diabetic nephropathy protection studies (2024–2025). As reported in Grokipedia.
31. 2025 pilot study on bilberry extract and mood parameters. As reported in Grokipedia.
32. Eandi M. "Clinical tolerability study of bilberry extract." Fitoterapia. 1996. As cited in ConsumerLab review.
33. Cignarella A, Nastasi M, Cavalli E, de Giuli L. "Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia." Thrombosis Research. 1996;84(5):311–322. https://doi.org/10.1016/S0049-3848(96)00195-8
34. Grokipedia. "Bilberry — Production." Accessed 2025. https://grokipedia.com/page/Bilberry. Production data: Swedish bilberry potential yield exceeds 800,000 tons; 2–5% commercially harvested.