Bilberry
Vaccinium myrtillus
A European wild blueberry rich in anthocyanins, long promoted for eyesight and circulation; its night-vision reputation is not supported by controlled trials, but it shows modest effects on eye fatigue, retinal blood vessels, and blood sugar.
At a Glance
- Best known for
- Antioxidant anthocyanins (among the richest food sources), Eye fatigue and dry eye from screen use (small RCTs), Diabetic and hypertensive retinopathy (older European studies)
- Evidence
- Preliminary
- Typical dose
- 480 mg extract (25% anthocyanins) daily
- Type
- Herb
What is Bilberry?
Bilberry is a low shrub of northern Europe, closely related to the North American blueberry, whose small dark-purple berries stain the mouth and fingers because their pigment runs all the way through the flesh. The berries have been eaten and used in folk medicine for diarrhea, scurvy, and poor circulation since the Middle Ages. Its modern reputation for eyesight traces to World War II stories of RAF pilots eating bilberry jam to sharpen night vision — a tale that later research has not confirmed. Bilberry extracts are now standardized by anthocyanin content and sold primarily for eye health, vascular support, and antioxidant protection.
Known Health Benefits
How It Works
Anthocyanins are potent scavengers of free radicals and also increase the activity of the body's own antioxidant enzymes. In the eye, they are proposed to accelerate the regeneration of rhodopsin (the light-sensitive pigment in rod cells), improve blood flow in the small vessels of the retina, and protect retinal cells from oxidative damage — mechanisms that are well demonstrated in laboratory and animal studies but only partially confirmed in people. In blood vessels, anthocyanins strengthen capillary walls by stabilizing collagen, reduce platelet aggregation, and improve endothelial function through nitric oxide pathways. The polyphenols also slow carbohydrate digestion and may improve insulin sensitivity.
What Research Says
The night-vision claim has been tested in several placebo-controlled trials, including a well-designed crossover study of young men with good vision that found no improvement in night visual acuity or contrast sensitivity after 3 weeks of bilberry extract. A 2004 systematic review reached the same negative conclusion. Evidence is more promising in other areas: a 2015 RCT of 281 Japanese office workers found 480 mg/day of standardized extract for 8 weeks modestly improved subjective and objective measures of eye fatigue, and small trials have reported benefit for dry eye symptoms. Older Italian studies from the 1980s reported reduced retinal hemorrhages in diabetic retinopathy, but these were small and poorly controlled. A 2014 double-blind trial in people with mild type 2 diabetes found a single large dose of bilberry extract reduced post-meal glucose and insulin. Trials of whole bilberries or juice have reported small improvements in inflammatory markers, HDL cholesterol, and blood pressure in people at cardiovascular risk. Overall the evidence is preliminary: encouraging for eye strain and metabolic health, negative for night vision, and in need of larger long-term studies.
Active Compounds
Anthocyanins (delphinidin, cyanidin, malvidin, petunidin, peonidin glycosides; 25–36% in standardized extracts), tannins, flavonols, phenolic acids
Forms & Bioavailability
Anthocyanins are absorbed quickly in the stomach and upper intestine, peaking in blood within 1–2 hours, but only a small fraction (typically 1–2%) reaches the circulation intact; much of the rest is metabolized by gut bacteria into phenolic acids that may themselves be active. Taking bilberry with a meal does not greatly reduce absorption, although a high-fat meal may slow it. Standardized extracts provide far more anthocyanin per dose than fresh fruit — 160 mg extract is roughly equivalent to 40–50 g of fresh berries. Anthocyanins have been detected in human eye tissue after supplementation, supporting the plausibility of direct ocular effects.
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Eye fatigue / screen strain | 480 mg extract (25% anthocyanins) daily |
| General antioxidant / vascular support | 160–320 mg extract daily |
| Blood sugar support | 160–480 mg extract with meals |
| Whole fruit | 50–100 g fresh or frozen berries daily |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- Fresh or frozen bilberries (seasonal in northern Europe)
- Bilberry jam, juice, and dried berries
- Blueberries, black currants, and aronia (similar but not identical anthocyanin profiles)
Potential Side Effects
Fruit and extract are well tolerated; very high doses may cause GI upset; bilberry leaf in large or prolonged amounts has caused toxicity in animals
Who Should Avoid It
- Bleeding disorders or upcoming surgery (antiplatelet effect; stop 2 weeks before procedures)
- Concurrent anticoagulant therapy without monitoring (warfarin, DOACs)
- Insulin or hypoglycemic drugs without glucose monitoring (additive lowering)
- Long-term use of bilberry leaf (hydroquinone content; toxicity reported in animals)
Pregnancy & Lactation
Bilberry fruit in food amounts is safe in pregnancy and breastfeeding. Standardized extracts have not been studied in these groups; while anthocyanins from food are not considered harmful, concentrated doses have theoretical antiplatelet effects, so most sources advise limiting supplements to food-level intake unless a clinician recommends otherwise. Avoid bilberry leaf preparations in pregnancy.
Known Drug Interactions
May enhance the effect of anticoagulant and antiplatelet drugs; may lower blood sugar additively with diabetes medications; leaf extract may interact with iron absorption
Evidence Classification
Based on in vitro studies, animal models, pilot trials, or traditional use documentation. Clinical evidence is limited.
Frequently Asked Questions
Does bilberry really improve night vision?
Probably not for people with normal eyes. The story originated with WWII pilots, but at least four placebo-controlled trials in healthy adults found no improvement in night vision, dark adaptation, or contrast sensitivity. There may be some benefit in people with existing retinal problems, but the evidence there is older and weaker. Bilberry's better-supported eye benefit is for eye fatigue in heavy screen users.
Are blueberries just as good as bilberries?
Blueberries are nutritionally similar and are an excellent source of anthocyanins, but bilberries contain roughly 3–4 times as much, with a different mix of pigments (more delphinidin). Eating blueberries regularly is a reasonable food-based substitute for general antioxidant intake, but the clinical trials of eye fatigue and metabolic effects used standardized bilberry extracts at doses not easily matched by eating fruit.
What should I look for on a bilberry supplement label?
Look for an extract standardized to 25–36% anthocyanins (sometimes labeled 'anthocyanosides' or 'anthocyanidins'), with the dose per capsule stated. Products listing only 'bilberry fruit powder' without standardization may contain very little anthocyanin. Bilberry is also a frequently adulterated botanical — some products have been found to contain cheaper dyes or other berries — so choose brands that third-party test.
Can bilberry help diabetic retinopathy?
Some small Italian trials from the 1980s reported fewer retinal hemorrhages in people with diabetic or hypertensive retinopathy taking bilberry extract, and the anthocyanins have plausible protective mechanisms. But these studies were small and not rigorously controlled, and there are no modern large trials. Bilberry is not a substitute for blood sugar control, regular eye exams, and standard retinopathy treatment.
References
- Bilberry. National Center for Complementary and Integrative Health (2020)View study
- Bilberry (Vaccinium myrtillus) extract improves eye fatigue: a randomized, double-blind, placebo-controlled study. Ozawa Y, Kawashima M, Inoue S, et al.. Journal of Nutrition, Health and Aging (2015)
- Vaccinium myrtillus (bilberry) extracts and night vision: a systematic review of placebo-controlled trials. Canter PH, Ernst E. Survey of Ophthalmology (2004)
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.