IngredientsAnthocyanosides (also written as anthocyanosides or, interchangeably in the modern scientific literature, as anthocyanins) are a class of water-soluble polyphenolic glycosides belonging to the flavonoid family. Anthocyanins are glycosides of the basic skeleton of anthocyanidin, and each anthocyanin has the same flavonoid skeleton, in which the chromophore is a glycone and is responsible for the color of the pigment. The term anthocyanoside is applied especially in the European phytopharmaceutical and clinical literature — particularly in reference to standardized extracts of Vaccinium myrtillus — where it designates the glycoside form (aglycone + sugar) as opposed to the free aglycone (anthocyanidin). Anthocyanidin plus a sugar molecule leads to an anthocyanin.
The structural backbone is the flavylium cation, a 2-phenylbenzopyrylium ring system. If this basic formula is substituted with hydroxy or methoxy groups at positions 2, 3, 4, 5, 7, 3′ or 5′, the resultant compounds are known as anthocyanidins, which are water insoluble, unstable to light and rapidly destroyed by alkali and thus not found too often in plants. However, the glycosides thereof, known as anthocyanins, are more stable and are found as native substances in the leaves, flowers, and fruits of plants.
The most commonly studied anthocyanins are based on six anthocyanidins: Pelargonidin (Pg), Cyanidin (Cy), Delphinidin (Dp), Peonidin (Pn), Petunidin (Pt), and Malvidin (Mv), but approximately 700 anthocyanins are reported to be isolated from plants. Saccharides, including glucose, galactose, rhamnose, arabinose, rutinose, xylose, sophorose, sambubiose, and/or glucorutinose are attached to the aglycone of anthocyanins. Also, anthocyanins can be acylated with aliphatic and aromatic acids, including caffeic, p-coumaric, p-hydroxybenzoic, gallic, succinic, oxalic, malonic, ferulic, and/or sinapic acids.
The glycosyl moiety of anthocyanosides, which is insoluble in cold water and can only be extracted in acidic aqueous medium, can be a monosaccharide, a disaccharide, or a trisaccharide. The total number of anthocyanins found in nature is extremely large, since many mono-, di- and tri-saccharides may be glycosylated at the 3, 5, or 7 positions, and also since the sugar at position 3 may be acylated.
The antioxidant capacity of individual anthocyanosides is related to the hydroxylation pattern of the B-ring. The structure–activity relationship of anthocyanin demonstrates that hydroxylation at positions C3′ and C5′ of the B-ring enhances the capacity for hydrogen donation, indicating that the B-ring primarily contributes to electron donation. Studies indicate that delphinidin exhibits the highest antioxidant activity among the six anthocyanidins, probably due to the presence of three hydroxyl groups at positions C3′, C4′, and C5′ of the B-ring.
These water-soluble compounds are synthesized in various plant tissues, including leaves, stems, fruits, and flowers, predominantly in response to environmental cues such as light exposure, temperature fluctuations, and nutrient availability. The accumulation of anthocyanins in plant tissues serves multiple purposes, including attracting pollinators, deterring herbivores, and protecting against environmental stresses such as UV radiation and pathogen attacks.
The most pharmacologically studied source is bilberry (Vaccinium myrtillus L., family Ericaceae). Bilberry is a small, dark blue berry closely related to the North American blueberry, native to Northern Europe, with a long history of traditional use both as food and medicine. In the supplement industry, V. myrtillus is the dominant source of standardized anthocyanoside extracts. Other commercially significant sources include blackcurrant (Ribes nigrum), elderberry (Sambucus nigra), chokeberry (Aronia melanocarpa), grape skin (Vitis vinifera), blueberry (Vaccinium corymbosum), and cherry (Prunus avium). Major sources of anthocyanins in the American diet are blueberries, cherries, raspberries, strawberries, black currants, purple grapes, and red wine.
Within the bilberry fruit specifically: Five different anthocyanidins in bilberry produce more than fifteen different anthocyanosides. The fresh fruit contains an anthocyanoside concentration of 0.1 to 0.25 percent. The five principal anthocyanidins in V. myrtillus are delphinidin, cyanidin, petunidin, peonidin, and malvidin, each glycosylated with arabinose, galactose, or glucose. Specific glycosides identified include delphinidin-3-O-arabinoside and delphinidin-3-O-galactoside.
Extracts from bilberry are usually refined to a range of 34 to 36% anthocyanosides, which corresponds to a content of 25% anthocyanidins (aglycones). Extracts are mainly prepared from the fresh bilberry fruits by a suitable procedure using ethanol (96% v/v) or methanol (minimum 60% v/v) at 10–60°C, diluted with water, filtered, and afterwards concentrated and refined.
Commercial supplement forms include: standardized dry extract tablets/capsules (the most common format, typically standardized to 25–36% anthocyanosides); liquid/fluid extracts; freeze-dried whole-fruit powder; fresh or frozen fruit; and traditional herbal decoctions. Typical bilberry products are standardized to 25% anthocyanoside content (approximately 36% anthocyanin), and 100 g of fresh fruit contains between 300 to 700 mg anthocyanin. Storage and processing of the fresh berries leads to degradation of anthocyanin content, and variations in bioavailability have been observed.
Bilberry has been used in European medicine for nearly one thousand years, primarily to treat diarrhea. Bilberry has had historic uses in traditional European medicine for nearly 1,000 years, with reported uses dating back as far as the early 12th century. Herbalists and physicians of the 16th century used it for a variety of ailments, including intestinal ailments; infections of the mouth, skin, and urinary tract; gout; and rheumatism. By the 20th century, individuals used bilberry extract as an anti-inflammatory, an anti-diarrheal, a diuretic, a cooling and restorative nutritive tonic, and a coagulator.
Their history of medicinal use dates back to antiquity, with the ancient Greek Dioscorides using them to treat diarrhea and dysentery. In the 18th century, German doctors prescribed the bilberry for intestinal conditions, among other things.
Traditional herbal remedies called for a strong tea made by steeping one-to-two tablespoons of dried bilberry fruit in five ounces of water for at least 10 minutes. Externally, poultices and washes from the astringent dried fruit were used for skin wounds and mouth/throat inflammations.
For centuries, European herbalists used bilberry and elderberry extracts to support vision, especially night vision, and to promote healthy circulation. The modern use of the bilberry dates back to World War II, when British Royal Air Force pilots reported that a good dose of bilberry jam just before a mission improved their night vision, often dramatically. While the veracity and magnitude of the RAF story are debated, it spurred scientific interest in bilberry's effects, particularly on vision and vascular health.
Traditional remedies also used berry extracts to manage varicose veins, hemorrhoids, and capillary fragility. Empirical uses also included diarrhea, vomiting, heaviness of the legs and varicosis, and hemorrhoids.
In 1987, Commission E, the German panel of experts that assesses the safety and effectiveness of herbs, approved the use of bilberry extract for diarrhea and inflammation of the mouth or throat. The Commission E monograph covers non-specific, acute diarrheal diseases and local therapy of mild inflammation of the oral and pharyngeal mucosa.
ESCOP (the European Scientific Cooperative on Phytotherapy) recommends the use of dried bilberry fruits as an adjunct treatment for acute non-specific diarrhea. Anthocyanosides present in bilberry fruits are largely responsible for the antioxidant action of the bilberry; bilberry extracts, particularly rich in anthocyanins, are recognized by ESCOP for the symptomatic treatment of issues related to varicose veins, and the EMA also recognizes bilberry as a traditional herbal remedy to relieve symptoms of skin capillary fragility.
The EMA's HMPC monograph for fresh bilberry fruit recognizes traditional use for feeling of heaviness in the legs in mild venous circulatory disorders, to relieve symptoms of skin capillary fragility, and spider veins, while anthocyanins from fresh bilberry fruits are traditionally used to prevent night blindness (as a registered traditional medicinal product).
Flavonoids, specifically anthocyanosides, are the most pharmacologically active constituents in bilberry fruit. In addition to anthocyanosides, bilberry fruit also contains catechin, epicatechin, condensed tannins, oligomeric procyanidins, and pectins. The active constituents isolated from the leaf of the bilberry plant include quercetin, catechins, tannins, and iridoids.
Anthocyanosides, also known as anthocyanins, are composed of an aglycone (e.g., anthocyanidin) bound to one of three glycosides (arabinoside, glucoside, or galactoside). In V. myrtillus, the five aglycone classes are delphinidin, cyanidin, petunidin, peonidin, and malvidin, each capable of forming glycosides with the three sugars, generating a profile of up to fifteen distinct anthocyanosides.
The antioxidant activity of anthocyanins can effectively eliminate free radicals, reduce the stimulation of inflammation, reduce the secretion of inflammatory factors, inhibit the activation of inflammation-related signal pathways, stimulate the production of anti-inflammatory factors, and effectively reduce the inflammatory reaction. Owing to rich hydroxyl groups in their chemical structures, anthocyanins represent one of the largest families of phenolic pigments with antioxidant and anti-inflammatory properties.
Anthocyanins exert anti-inflammatory effects through modulation of Toll-like receptors, MAPKs, NF-κB signaling, and oxidative stress pathways. At the molecular level, treatment with anthocyanins leads to the activation of signaling pathways including ERK1/2 and Akt, while significantly inhibiting the phosphorylation of IκBα and suppressing the activation of NF-κB subunits p50 and p65, which are transcription factors responsible for inflammation.
In the context of rheumatoid arthritis models, anthocyanins exert protective effects through multiple molecular mechanisms, including immunomodulation (inhibiting Th17, promoting Treg, regulating Tfh/Tfr, and downregulating CD38+ NK cell activity), anti-inflammatory responses (blocking the IL-17A/IL-17RA/JAK-STAT3 pathway, inhibiting NF-κB and MAPKs, reducing FLS proliferation and migration, and suppressing inflammatory factors such as TNF-α, IL-1β, and IL-6), and joint protection (inhibiting MMPs/collagenase and osteoclast differentiation).
The pharmacology of V. myrtillus is discussed almost entirely in relation to its anthocyanoside content because research has focused primarily on the anthocyanosides. Anthocyanosides possess significant collagen-stabilizing action. Collagen, the most abundant protein of the body, is responsible for maintaining connective tissue integrity, and is destroyed during the inflammatory processes that occur in rheumatoid arthritis, periodontal disease, and other inflammatory conditions involving bones, joints, cartilage, and other connective tissue.
Anthocyanidins, proanthocyanidins, and other flavonoids are remarkable in their ability to prevent collagen destruction. The anthocyanidins in V. myrtillus extracts affect collagen metabolism by cross-linking collagen fibers, resulting in strengthening of the natural cross-linking of the collagen that forms the collagen matrix of connective tissue. Anthocyanosides also appear to strengthen collagen, the protein that provides support to healthy connective tissue.
Studies show that anthocyanosides may strengthen blood vessels, improve circulation, and prevent the oxidation of LDL ("bad") cholesterol, a major risk factor for atherosclerosis. Anthocyanosides support normal formation of connective tissue and strengthen capillaries in the body, and may also improve capillary and venous blood flow.
In vitro, animal, and clinical research suggest that anthocyanidin extracts from bilberry can inhibit platelet aggregation. This antiplatelet effect is relevant both to their potential cardiovascular benefits and to safety considerations in patients taking anticoagulant drugs.
Bilberry anthocyanosides promote rhodopsin synthesis and regeneration, increase retinal sensitivity to changes in light intensity, improve visual acuity and dark adaptation, as well as blood supply of the retina. Anthocyanosides are expected to improve vision by enhancing the activity of metabolic enzymes in the retina.
Pharmacokinetic studies in animals and humans show that absorption and bioavailability of anthocyanins is low, with mean maximal plasma concentrations reached in approximately 1.5 hours. The extensive metabolism exerted by the microflora in the colon plays a critical role in the bioavailability of anthocyanins. Bacteria of the intestinal microbiota have a vast array of enzymes which participate in metabolism of anthocyanins, including β-d-glucosidase, β-d-glucuronidase, α-galactosidase, and α-rhamnosidase activities, which lead to the cleavage of glycosidic bonds.
There is a high inter- and intra-individual variation in the response to anthocyanin intake that in many cases leads to contradictory results in human trials. Variability in anthocyanin bioavailability may be produced by the lack of homogeneity introduced at three different levels: food matrix and food processing, enzymes involved in anthocyanin metabolism and transport, and anthocyanin-metabolizing gut microbiota.
Upon consumption, anthocyanins are quickly absorbed and can penetrate the blood–brain barrier (BBB). Research based on population studies suggests that including anthocyanin-rich sources in the diet lowers the risk of neurodegenerative diseases.
Many authors have observed that the intake of anthocyanins causes an increase in beneficial bacteria such as Bifidobacteria, Lactobacilli, or Actinobacteria. The modulation of gut microbiota by anthocyanin increases short-chain fatty acid (SCFA)-producing bacteria, which acidify the intestinal pH and inhibit pathogenic bacteria proliferation, while SCFA such as butyrate act as a fuel to provide energy for epithelial cells, improving the intestinal barrier.
The most historically prominent claim for anthocyanosides is enhancement of night vision, rooted in both tradition and the World War II RAF anecdote. While earlier trials suggested that taking bilberry could benefit people with night blindness, more recent trials with healthy volunteers found no effect of bilberry on night vision. Bilberry anthocyanosides enhance the regeneration of rhodopsin, an eye protein necessary for vision in dim light or at night, and have been used to improve visual acuity and night vision; however, although a report of improved night vision among air traffic controllers supports these claims, other recent well-controlled clinical trials did not show any benefit on night visual acuity or contrast sensitivity in subjects with normal vision.
Evidence strength: The mechanistic rationale is plausible, but the clinical evidence for night vision improvement in individuals with normal baseline vision is not confirmed by rigorous placebo-controlled trials. Effects in populations with pre-existing deficits or retinal pathology remain under investigation.
Preliminary human trials conducted in Europe show that bilberry may help treat people with mild retinopathies, such as macular degeneration and diabetic retinopathy. A key early study was described as follows: in a double-blind study, 14 patients with diabetic and/or hypertensive retinopathy were supplemented with bilberry extract equivalent to 115 mg anthocyanosides daily (or placebo) for one month, and improvements in symptoms were reported. Studies conducted in Russia have been aimed at evaluating the use of bilberry anthocyanoside preparations in age-related macular degeneration, diabetic retinopathy, primary open-angle glaucoma, and other diseases.
Bilberry anthocyanosides have been shown to improve symptoms and complications of both insulin-dependent and non-insulin-dependent diabetes mellitus related to the macrovasculature and microvasculature, and a positive influence on the permeability and tendency of retinal microvasculature to hemorrhage has been observed.
In recent studies of the extract's effects on health, the most compelling evidence is its reduction of retinal inflammation — although studies have been small and mostly conducted in lab animals.
Evidence strength: Preliminary and suggestive. Small clinical trials have reported positive outcomes in retinopathy, but most were conducted in the 1980s–1990s with limited methodological rigor. Larger, adequately powered RCTs are lacking.
Animal studies show that diets high in anthocyanoside flavonoids retard the development of cataracts in rats. A clinical study in which bilberry extract (180 mg twice daily of a 25% anthocyanoside extract) was given with vitamin E demonstrated arrested cataract formation in 48 of 50 patients with senile cataracts. In one study of 50 patients with age-related cataracts, it was found that taking bilberry extract along with vitamin E supplements stopped the progression of cataracts in nearly all of the participants.
Evidence strength: Preliminary. The single clinical study cited was an early, small Italian study lacking a placebo arm; it is widely referenced but not replicated by adequately controlled modern trials.
In humans, several small to medium-sized randomized controlled trials (RCTs) have assessed the effects of purified anthocyanins and anthocyanin-rich extracts on validated biomarkers of CVD in populations of both healthy and diseased adults. A 2016 systematic review published in Nutrients that included twelve RCTs found: supplementation with anthocyanins significantly improved LDL cholesterol among diseased individuals or those with elevated biomarkers. Supplementation did not significantly affect other markers of CVD in either healthy individuals or those with elevated markers. Crucially, no adverse effects of anthocyanins were reported across studies at levels up to 640 mg/day.
A subsequent 2017 systematic review and meta-analysis in the American Journal of Clinical Nutrition examined RCTs of ≥2 weeks' duration: it concluded that anthocyanins have favorable overall effects on LDL, and reported that anthocyanins could significantly improve LDL, but not other markers of CVD, among diseased individuals.
A larger 2022 meta-analysis of 44 RCTs and 15 prospective cohort studies noted: a previous meta-analysis of prospective studies found that frequent intake of anthocyanin-rich foods was related to a 9% lower risk of coronary heart disease. In addition, anthocyanin intake could substantially improve endothelial function and alleviate arterial stiffness among subjects with high cardiovascular risks. However, about half of the included RCTs obtained financial support from the berry industry or industry associations, which might lead to selective reporting of positive results; nevertheless, subgrouping by funding source did not find any more benefits of purified anthocyanins or anthocyanin-rich berries on each surrogate marker of CVDs.
Human intervention studies using berries, vegetables, parts of plants and cereals (either fresh or as juice) or purified anthocyanin-rich extracts have demonstrated significant improvements in LDL oxidation, lipid peroxidation, total plasma antioxidant capacity, and dyslipidemia, as well as reduced levels of CVD molecular biomarkers.
Evidence strength: Moderate. Multiple RCTs and meta-analyses support a consistent, statistically significant reduction in LDL cholesterol in individuals with elevated markers. Effects on blood pressure, HDL, and triglycerides are less consistent. The evidence base is hampered by heterogeneity in anthocyanin sources, doses, populations, and study duration.
Bilberry extracts, particularly rich in anthocyanins, are recognized by ESCOP for the symptomatic treatment of issues related to varicose veins, and the EMA also recognizes bilberry as a traditional herbal remedy to relieve symptoms of skin capillary fragility. The ESCOP monograph recognizes use for varicose vein complaints, aching, heavy legs, micro veins in the eye, and peripheral vascular insufficiency.
Taking 480 mg/day of bilberry extract is associated with a significant improvement in microcirculation. The same dosage of bilberry extract administered to 47 patients with various venous disorders resulted in a reduction in capillary flow as well as elimination of micro-stagnation and foot stasis.
Pharmacological studies in humans showed anti-inflammatory and antithrombotic effects, while clinical studies showed improvements in symptoms of dry eye, venous insufficiency, metabolic syndrome, and reduced inflammatory mediators.
Evidence strength: Moderate, supported by regulatory recognition from both ESCOP and the EMA. Clinical studies are relatively small; however, traditional use and mechanistic data supporting capillary-wall strengthening effects are consistent.
Epidemiologic evidence indicates that incorporating anthocyanin-rich foods into the diet may lower the risk of type 2 diabetes, blood pressure, and cardiovascular diseases. Experimental studies suggest that the beneficial effect mechanisms of anthocyanins mainly involve insulin-dependent and insulin-independent pathways.
Because bilberry appears to lower blood sugar, it could make the effects of diabetes medication stronger. Preliminary evidence suggests that bilberry leaf might lower blood glucose.
Research has not turned up conclusive evidence about bilberry extract's effect on blood glucose levels, or heart or gut health from the extract alone.
Evidence strength: Preliminary for the extract form. Epidemiological and dietary intervention data for anthocyanin-rich foods are more consistent, but intervention data for isolated bilberry anthocyanoside extracts on glycemic endpoints are limited.
Promising evidence is emerging for the procognitive, anti-inflammatory, and neuroprotective properties of dietary flavonoids, particularly anthocyanins. The neuroprotective effects of anthocyanins are supported by evidence from in-vitro studies using fruit extracts, and pre-clinical rodent studies support the in-vitro findings by showing promising effects of anthocyanins on various aspects of cognitive function, such as long-term memory, spatial-working memory, and object-recognition memory.
Recent systematic reviews of human studies that have assessed the effect of habitual blueberry consumption as a source of anthocyanins reported general improvement in some aspects of cognitive performance, including verbal memory and mood. Clinical trials suggest that dietary anthocyanins may enhance cognitive function; a 2024 systematic review and meta-analysis aimed to identify the effect of anthocyanin on cognition and mood in adults.
Although a substantial body of preclinical research supports metabolic and cognitive benefits of anthocyanins, most of the evidence arises from in vitro or animal models. Well-designed human trials are required to determine optimal doses, formulations, safety profiles, and bioavailability in clinically relevant populations.
Evidence strength: Emerging and promising. In vitro and animal data are consistent. Human RCT data show trends toward improvement in specific cognitive domains, particularly in older adults, but the field is heterogeneous and large-scale definitive trials are still ongoing.
The effects of anthocyanosides on collagen structures and their potent antioxidant activity make V. myrtillus anthocyanoside extracts useful in the treatment of a wide variety of inflammatory conditions, most notably rheumatoid arthritis. Bioflavonoids have been found to increase collagen synthesis and inhibit collagen catabolism in rats with adjuvant-induced arthritis, a chronic progressive polyarthritis with some similarities to rheumatoid arthritis.
Bilberries, like cherries, are particularly beneficial in the treatment of gout, as not only do their flavonoids, phenolic acids, and tannins effectively reduce uric acid levels, but their anthocyanosides' antioxidant and anti-inflammatory actions also help to prevent tissue destruction.
Evidence strength: Primarily preclinical (animal and in vitro). Human clinical trial data specifically for arthritis or gout using standardized anthocyanoside extracts are limited; most evidence is extrapolated from dietary studies.
Bilberry is believed to help people with diarrhea by reducing intestinal inflammation. No studies, however, have examined bilberry's use for diarrhea in a controlled clinical setting. The use for diarrhea is supported largely by the well-documented astringent activity of tannins in dried bilberry fruit, and is recognized by both the German Commission E and ESCOP.
The modulation of gut microbiota by anthocyanin increases SCFA-producing bacteria, which acidify the intestinal pH and inhibit pathogenic bacteria proliferation; it is suggested that the potential beneficial functions of anthocyanins could be indirectly attributed to gut microbiota modulation and consequent production of metabolites due to bacterial fermentation activities, which improve several parameters related to intestinal health.
Evidence strength: The use of dried bilberry fruit for diarrhea has traditional and monograph-level regulatory support. The microbiome-modulating effects are based on in vitro and early clinical data; robust human trials specifically testing gastrointestinal endpoints are lacking.
The standard dosage of bilberries reported in the literature is 120 to 240 milligrams (mg) twice daily of an extract standardized to contain 25 percent anthocyanosides.
Traditional dosages range from dried berries 20 to 60 g/day, or fresh berries 100 to 300 g/day. Limited clinical studies have evaluated daily supplemental bilberry 100 to 400 g over 4 to 8 weeks' duration.
In specific clinical studies:
Commercial extracts are usually refined to the range of 34 to 36% anthocyanosides, which corresponds to a content of 25% anthocyanidins (aglycones).
Preparations used in traditional/decoction contexts: a decoction is prepared by placing 5–10 grams (1–2 teaspoons) of mashed berries in cold water, then bringing to a simmer for 10 minutes, then straining. A leaf tea is prepared by steeping 1 gram (1–2 teaspoons) of finely chopped dried leaf in 150 mL boiling water for 5–10 minutes, then straining.
Extensive toxicological investigations have demonstrated that bilberry anthocyanoside extracts are devoid of toxic effects. Bilberry fruit consumption is very safe, and virtually no side effects have been reported. Dosages as high as 400 mg/kg body weight have been administered to rats without toxicity. Long-term oral administration in humans of doses equivalent to 180 mg/kg anthocyanosides per day for six months produced no toxic effects. No mutagenic or carcinogenic effects were observed.
Preclinical safety data for bilberry fruit extract showed no mutagenic or cytotoxic effects. Clinical safety assessment in humans confirmed the safety of bilberry extract; daily use for six months produced no toxic effects.
Since bilberry extracts have antiplatelet aggregating properties, very high doses should be used cautiously in patients with hemorrhagic disorders and those taking anticoagulant or antiplatelet drugs. Because the anthocyanosides in bilberry may stop blood from clotting, there may be an increased risk of bleeding if taken with blood-thinning medication, including aspirin.
The interaction with warfarin is documented but complex. The reduction of warfarin activity is unexpected, since the bilberry anthocyanosides, retaining antiplatelet properties, should increase the bleeding risk when co-administered with anticoagulant and antiplatelet drugs. In an Italian spontaneous reporting database analysis (2002–2009), 12 reports were identified involving 7 cases of INR reduction in patients treated with warfarin or acenocoumarol and 5 cases of INR increase; in one case, INR reduction occurred after assumption of warfarin and bilberry concentrate juice. The interaction mechanism is unknown.
Because bilberry appears to lower blood sugar, it could make the effects of diabetes medication stronger. Also, taking bilberry with other herbs that also lower blood sugar may result in hypoglycemia (low blood sugar). As preliminary evidence suggests that bilberry leaf might lower blood glucose, diabetes drugs might require dosing adjustment if bilberry leaf is used.
An important safety distinction exists between bilberry fruit and bilberry leaf preparations. Medical authorities distinguish sharply between bilberry fruit and bilberry leaves when it comes to safety. Evidence shows that bilberry leaves contain compounds that become toxic with prolonged exposure or high doses. The specific toxic compounds in bilberry leaves have not been fully characterized, but animal studies document wasting syndrome, anemia, and jaundice with chronic leaf consumption. Bilberry leaf should not be used long-term.
Bilberry has GRAS (Generally Recognized As Safe) status when used as food. Avoiding doses above those found in food is advisable because safety and efficacy at higher doses are unproven.
Several overarching limitations apply to the clinical evidence for anthocyanosides. There is a high inter- and intra-individual variation in response to anthocyanin intake that in many cases leads to contradictory results in human trials. Heterogeneity in food matrices, processing, individual metabolic phenotypes, and microbiota composition influences polyphenol bioavailability and response to supplementation; this variability necessitates personalized and integrative approaches when recommending these compounds in clinical practice.
Significant between-study heterogeneity has been observed in meta-analyses even after subgroup analysis stratified by various study characteristics. Future well-designed clinical trials are warranted to clarify the sources of heterogeneity. Studies of the specific standardized anthocyanoside extract form are often older, small in sample size, and unpublished in peer-reviewed English-language literature.
Health conditions that Anthocyanosides may help support.
Anthocyanosides (glycosidic forms of anthocyanidins) are the principal active forms of anthocyanins in bilberry and related plants, with documented clinical effects on capillary strength, microcirculation, and venous health. Clinical trials with bilberry extract standardised to anthocyanosides show improvements in capillary permeability, chronic venous insufficiency, and diabetic microangiopathy. They are the primary constituent responsible for bilberry's circulatory properties.
Anthocyanosides are glycoside forms of anthocyanins found in bilberry and black currant, studied specifically for VDT-related eye fatigue. Nakaishi et al. (Altern Med Rev 2000) demonstrated that black currant anthocyanoside intake reduced VDT work-induced transient refractive alteration in humans. A PMC review (2019) confirms anthocyanosides relieve ciliary muscle tension, a primary driver of digital eye fatigue.
Anthocyanosides are flavonoid pigments from bilberries and related berries with capillary-strengthening and venoprotective properties relevant to hemorrhoids. EBSCO Research Starters identifies bilberry anthocyanosides as a principal proposed natural treatment for hemorrhoids. A 2021 PMC retrospective study incorporating Vaccinium myrtillus extract (anthocyanosides) achieved 89.8% hemorrhoid grade reduction in grade II–III disease.
Anthocyanosides are glycoside forms of anthocyanins, the active constituents of bilberry and black currant extracts most closely associated with night vision research. They are proposed to accelerate rhodopsin regeneration and support retinal vascular function. Clinical evidence is stronger for black currant anthocyanosides than for bilberry anthocyanosides, though both have been extensively studied.
Anthocyanosides are the flavonoid glycosides found in bilberry, blueberry, and other berries that have vasoactive and vasoprotective properties relevant to varicose veins. They stabilize collagen in vessel walls, reduce capillary permeability and fragility, and have demonstrated vasoactive properties in research (Bell & Gochenaur, J Appl Physiol 2006). They are the basis for bilberry's traditional and modern recommendation for venous insufficiency and varicose vein-related conditions.
Body systems that Anthocyanosides may help support.
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