- Dwarf bilberry
- European blueberry; whortleberry
- Bog bilberry
- Chinese blueberry
For Patients & Caregivers
How It Works
Bilberry is used in traditional medicine to treat eye disorders and support vision health, but clinical data for these purposes are mixed or lacking. There is insufficient evidence to support its other uses.
Compounds in bilberry called anthocyanins can regenerate rhodopsin, a pigment found in retinal cells responsible for eyesight. This is one of the reasons it has gained popularity in traditional medicine to support eye health.
In laboratory studies, bilberry reduces inflammation and fluid accumulation in tissues, acts as an antioxidant, inhibits blood clotting, and strengthens the walls of blood vessels. Bilberry extracts can inhibit the growth of cancer cells in the lab. Initial studies in humans also show that bilberry may have anti-cancer effects, relieve certain types of inflammation, or improve the biological profiles of those at higher risk for heart disease or diabetes. More clinical trials are needed to confirm these effects.
To prevent cancer
Laboratory studies and one clinical study suggest anti-cancer effects. More research is needed.
To treat eye disorders
One small study suggests bilberry may improve visual function in some patients with normal tension glaucoma. But others produced mixed data.
To treat circulatory disorders
Laboratory studies show that bilberry may protect blood vessels and decrease the risk of blood clots. Human data are needed.
To treat diabetic retinopathy
Evidence is lacking to support this claim.
To treat diarrhea
Evidence is lacking to support this claim.
To reduce chemo-induced mucositis
Small studies have shown that formulas containing bilberry fruit help prevent chemo/radio-induced mucositis.
To improve visual acuity
Clinical trial results are mixed on whether bilberry can help improve vision.
Do Not Take If
- You use warfarin or other blood thinners: Bilberry may increase the risk of bleeding.
- You use aspirin or aspirin products: Bilberry may increase the risk of bleeding. Clinical relevance is not known.
- You use non-steroidal anti-inflammatory drugs (NSAIDs): Bilberry may increase the risk of bleeding. Clinical relevance is not known.
For Healthcare Professionals
Bilberry fruit grows on perennial fruit trees or shrubs, and is closely related to the huckleberry and blueberry. It is marketed as a dietary supplement to help improve eyesight and promote overall eye health, and is widely used in herbal therapy. The anthocyanins in bilberry are thought to regenerate rhodopsin, a pigment present in retinal photoreceptor cells.
In vitro, bilberry polyphenols appear to protect against neurodegenerative processes and eye disorders (1) (2). Animal models suggest that bilberry extract may help visual functioning (3) and protect against retinal diseases (4). A small clinical study indicates utility of bilberry for improving visual function in some individuals with normal tension glaucoma (8), but others produced mixed data on whether or not bilberry anthocyanosides improve visual acuity, night vision, or retinal function (5) (6); many of the positive studies are also poorly designed (7). Further research is needed.
In other studies, a standardized bilberry extract was shown to reduce disease activity in patients with mild to moderate ulcerative colitis (10). Dietary bilberry produced beneficial changes in serum lipids and lipoproteins in women with higher metabolic risk, but had an unexpected opposite effect in those who were at low risk (11). Ingestion of bilberries in a diet that also included whole grain/low-insulin-response grain products and fatty fish altered lipid profiles and improved glucose metabolism in individuals at high risk for type 2 diabetes (13). Small studies suggest that bilberry fruit may help reduce risk of cardiovascular diseases (36); and that bilberry juice may be useful in decreasing biomarkers of inflammation and in improving cardiometabolic risk (14) (15). However, consumption of bilberry juice resulted in small to moderate increases in exercise-induced delayed onset muscle soreness and C-reactive Protein (37).
Bilberry has also been investigated for its anticancer potential. Preclinical findings indicate that it has anticancer effects (4) (16) (17) (18) (19) (20) (21); and exerts protective effects against chemo-induced oral mucositis (23). Small clinical studies found bilberry extract to affect reductions in proliferation of colorectal cancer cells (22); and a proprietary mixed herbal extract helped relieve chemo/radiotherapy-induced mucositis in pediatric (24) and adult cancer patients (25). However, the extent to which bilberry itself was responsible for such effects is unclear.
Mechanism of Action
In vitro, bilberry polyphenols inhibited amyloid fibril formation and dissolved preformed toxic aggregates and mature fibrils, suggesting a role in controlling fibril formations of various proteins that occur with neurodegenerative diseases (1). Bilberry anthocyanins modulated oxidative stress defense enzymes heme oxygenase-1 (HO-1) and glutathione S-transferase-pi (GST-pi) in human retinal pigment epithelial cells (2). In vitro and in vivo, bilberry inhibited angiogenesis through inhibition of ERK 1/2 and Akt phosphorylation (4). In an animal model of uveitis and retinal inflammation, pretreatment with a bilberry extract prevented photoreceptor impairment, relieved intracellular ROS elevation, activated retinal NF-ĸB in the inflamed retina, and suppressed the decrease of rhodopsin via inhibition of IL-6, which activates STAT3, thereby protecting outer segment length in photoreceptor cells (3). In a monocytic cell line, quercetin, epicatechin, and resveratrol inhibited lipopolysaccharide (LPS)-induced NF-kappaB activation (14).
In individuals with hypercholesterolemia, anthocyanins may improve endothelium-dependent vasodilation by activating the NO-cGMP signaling pathway (28). The polyphenols in bilberry juice can modulate inflammation by decreasing plasma C-reactive protein, interleukin (IL)-6, -15, and monokine induced by INFγ (MIG) (14).
In human colon and liver cancer cell lines, bilberry anthocyanins demonstrated intracellular antioxidant activity even though concentrations applied were very low (29). Bilberry extract inhibited human leukemia, colon, and breast cancer cells through apoptotic induction and/or inhibition of cell proliferation (17) (30). Delphinidin and other anthocyanidins synergistically enhanced cell-cycle arrest and apoptotic induction in aggressive non-small-cell lung cancer cells by modulating Notch, WNT, and NF-ĸB signaling pathways (16).
- Rectal bleeding: In a 77-year-old man on warfarin therapy, following long-term over consumption of bilberry that required two emergency room visits, treatment with fresh plasma infusions, and hospitalization to evaluate inconsistent international normalized ratio (INR) values (34).
Anticoagulants / Antiplatelets: Bilberry was shown to potentiate the risk of bleeding (34).
Aspirin and aspirin products: Bilberry can have added or synergistic antiplatelet effects, and increase the risk of bleeding (35). Clinical relevance is not known.
Non-steroidal anti-inflammatory drugs (NSAIDs): Bilberry may have added or synergistic antiplatelet effects, and increase the risk of bleeding (35). Clinical relevance is not known.