- Dwarf bilberry
- bog bilberry
- European blueberry
- bog bilberry
- Chinese blueberry
For Patients & Caregivers
Bottom Line: 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 studies are needed.
- To treat eye disorders
One small study suggests bilberry may improve visual function in some patients with normal tension glaucoma, but human data are generally lacking. The effect of bilberry on other eye conditions has been explored in animal and test tube studies, or in older studies with weak trial designs.
- To reduce inflammation
A few preliminary studies suggest that bilberry may be helpful in preventing or treating gastrointestinal mucositis, or for those with mild to moderate ulcerative colitis. Other small studies indicate that bilberry may improve biomarkers of inflammation related to cardiovascular disease. Larger confirmatory studies are needed.
- To improve vision, especially at night
Clinical trial results are mixed on whether bilberry can help improve vision, and do not support this use in individuals with good vision.
- To treat diarrhea
No scientific evidence supports this specific use, although one small study indicates bilberry may be helpful in mild to moderate ulcerative colitis.
- To treat circulatory disorders
Laboratory studies show that bilberry may protect blood vessels and decrease the risk of blood clots. Human data are needed.
A small study in humans suggests that bilberry extract may decrease tumor growth in colorectal cancer. However, additional studies are needed to confirm this effect.
A small study in patients with mild to moderate ulcerative colitis suggests that bilberry may be helpful in controlling symptoms. Larger randomized trials are needed to confirm these effects.
Reduce risk for heart disease and diabetes
A preliminary randomized trial that evaluated several berry formulations including frozen bilberries noted an improvement in overall biomarkers for overweight women at a higher risk for heart disease or diabetes.
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. Bilberry anthocyanins are thought to regenerate rhodopsin, a pigment in retinal photoreceptor cells, and bilberry has been used for poor night vision, macular degeneration, glaucoma, and cataracts.
In vitro, isolated bilberry polyphenols appear to protect against neurodegenerative processes and eye disorders (1)(2). Animal models suggest the extract may help visual functioning (3) and protect against retinal diseases (4). Human studies are mixed on whether bilberry anthocyanosides improve visual acuity, night vision, and retinal function (5)(6) and many of the positive studies are poorly designed (7). A small trial suggests bilberry may improve visual function in some individuals with normal tension glaucoma (8), but generally human data on bilberry for eye disorders are lacking (9).
A standardized bilberry extract was shown to reduce disease activity in a pilot study of 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 low-risk (11). Another species of bilberry, Caucasian whortleberry, was found to improve glycemic control in type 2 diabetic patients (12). Ingestion of bilberries in a diet that also included whole grain/low-insulin-response grain products and fatty fish also altered lipid profiles and improved glucose metabolism in individuals at high risk for type 2 diabetes (13). Two small randomized trials suggest that bilberry juice may reduce biomarkers of inflammation and improve cardiometabolic risk (14)(15).
In vitro and in vivo studies indicate that bilberry may have anticancer activities (4)(16)(17)(18)(19)(20)(21). A pilot study suggests bilberry extract may significantly reduce proliferation of colorectal cancer tumor tissue (22). Bilberry extract has a protective effect against chemotherapy-induced oral mucositis in an animal model (23). Other small studies of a proprietary extract combination that includes bilberry suggests it may relieve chemotherapy-induced mucositis in cancer patients (24)(25). However, it is unclear the extent to which bilberry itself may be responsible for this effect. More studies are needed to determine what benefits are attributable to bilberry fruit itself, as well as its potential synergy with other berry compounds and food combinations.
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 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 can inhibit human leukemia, colon, and breast cancer cells through apoptotic induction and/or inhibition of cell proliferation (17)(30). Delphinidin and other isolated anthocyanidins synergistically enhanced cell-cycle arrest and apoptotic induction in aggressive non-small-cell lung cancer cell lines by modulating Notch, WNT, and NF-ĸB signaling pathways (16). Their malfunction in cancers fuel cell regeneration and chemotherapy-resistance, and delphinidin particularly appeared to be the most effective at Notch1 and NF-ĸB inhibition (16).
In human studies, bilberry anthocyanins are excreted in the urine either intact or as methylated or glucuronidated metabolites (19)(22). The stomach appears to be the predominant site for anthocyanin absorption (31). Despite unfavorable pharmacokinetics, these anthocyanins appear to have intracellular antioxidant activity (29).
In animal studies, oral administration showed moderate GI absorption with <2% bioavailability (32). Peak levels were achieved within 15 minutes with a three-compartment distribution and elimination shown. Elimination was primarily through urine and bile.
Rectal bleeding with long-term bilberry overconsumption: In a 77-year-old man on warfarin therapy, requiring 2 emergency department visits, treatment with fresh plasma infusions, and hospitalization to evaluate inconsistent international normalized ratio (INR) values (33)(34).
Anticoagulants / Antiplatelets: Bilberry may potentiate the risk of bleeding (33)(34).
Aspirin and aspirin products: May have added or synergistic antiplatelet effects and increase bleeding risk (35).
Non-steroidal anti-inflammatory drugs (NSAIDs): May have added or synergistic antiplatelet effects and increase bleeding risk (35).
Chemotherapy drugs: Bilberry may interfere with the actions of certain chemotherapy drugs and radiation therapy (25) .
Larmo PS, et al. Effects of sea buckthorn and bilberry on serum metabolites differ according to baseline metabolic profiles in overweight women: a randomized crossover trial. Am J Clin Nutr. 2013;98:941-951.
In this randomized crossover trial, 80 overweight women consumed either frozen bilberries, or one of three sea buckthorn formulations for 30 days to compare the effects of these regimens on metabolic profiles, which were quantified from serum samples using 1H nuclear magnetic resonance spectroscopy. Even though most changes in individual metabolites were not statistically significant after correction for multiple testing, clear trends produced significant overall effects: P<.001 to .003 for all interventions on overall metabolic profiles, both in participants who had higher baseline cardiometabolic risk (Group B: P=.001 to .008) and those with lower-risk (Group A: P<.001 to .009). Unexpectedly for those taking bilberry, there were beneficial changes in serum lipids and lipoproteins in Group B but not in Group A. Investigators determined that the effects of bilberry on serum metabolites differed according to baseline metabolic profiles in overweight women, but could not explain the observed opposite effect in women with low-risk metabolic profiles.
Biedermann L, et al. Bilberry ingestion improves disease activity in mild to moderate ulcerative colitis - an open pilot study. J Crohns Colitis. 2013;7:271-279.
This open pilot trial with 9 weeks’ follow-up evaluated a standardized anthocyanin-rich bilberry preparation taken daily by 13 patients with ulcerative colitis. Assessments included clinical, biochemical, endoscopic and histologic parameters. At the end of the 6-week treatment, 63.4% of patients achieved the primary endpoint of remission, and 90.9% of patients had shown a response. All patients had decreased total Mayo scores (mean: screening, 6.5; week 7, 3.6; P<.001). Fecal calprotectin levels also significantly decreased, including 4 patients with undetectable levels post-treatment. Beneficial effects were confirmed by a decrease in endoscopic Mayo score and histologic Riley index. However, increases in calprotectin levels and disease activity were observed after intervention cessation. No serious adverse events were reported, and randomized clinical trials are warranted.
Thomasset S, et al. Pilot study of oral anthocyanins for colorectal cancer chemoprevention. Cancer Prev Res (Phila). 2009 Jul;2(7):625-33.
This unblinded study enrolled 25 patients with colorectal cancer (n=15) or colorectal liver metastases (n=10) who were scheduled to undergo resection of the primary tumor. The patients were randomized to receive a daily dose of mirtocyan, an anthocyanin-rich bilberry extract, until 7 days before surgery. Immunohistochemical observations were made in biopsy samples pre-intervention and compared with resection tissue post-intervention. Plasma concentrations of insulin-like growth factor (IGF-1) were also measured pre- and post-intervention. The proliferation index reflected by Ki-67 staining of colorectal tissue significantly decreased by 7% (P=.003) in all patients receiving mirtocyan extract, and was as high as 9% (P=.021) in one dosage group. After receiving mirtocyan, patients also experienced a small but nonsignificant reduction in circulating IGF-1 concentrations. The investigators also found mirtocyan to be safe and well tolerated.