Editorial note: Bilberry Extract is used in dietary supplements as a nutritional or botanical ingredient to support normal body function in generally healthy adults. It is not a medication and is not intended to diagnose, treat, cure, or prevent any disease.
What Is Bilberry Extract?
Bilberry (Vaccinium myrtillus) is a small shrub native to Europe and the northern parts of North America and Asia, closely related to the North American blueberry. Its berries contain exceptionally high concentrations of anthocyanins, a class of water-soluble flavonoid pigments that give the berries their deep purple-blue colour. Bilberry anthocyanins include 15 different anthocyanin compounds, a diversity that provides broad-spectrum free radical scavenging and antioxidant support.
Bilberry's association with vision health is one of the oldest stories in phytomedicine, RAF pilots in World War II reportedly consumed bilberry jam before night missions, claiming it improved their night vision and dark adaptation. While this anecdote is often repeated, the more substantiated basis for Bilberry's use in vision support lies in its documented effects on ocular microcirculation and retinal antioxidant protection, which are more consistently observed in research than the night vision effect.
How It Works: Mechanism of Action
Bilberry anthocyanins support visual health through two primary mechanisms. First, they strengthen and protect the walls of the tiny capillaries supplying blood to the retina, choroid, and ciliary body, the ocular microvasculature. Anthocyanins stabilise collagen in capillary walls by inhibiting collagen-degrading enzymes (collagenase, elastase, hyaluronidase), and reduce capillary permeability and fragility. Healthy retinal microcirculation is essential for photoreceptor nutrient supply and waste removal.
Second, Bilberry anthocyanins are potent antioxidants that accumulate in retinal tissue, where they protect photoreceptors and the retinal pigment epithelium from oxidative damage from light exposure. Research has also examined their role in rhodopsin regeneration, rhodopsin is the photopigment in rod cells responsible for dim-light vision. Anthocyanins appear to facilitate the regeneration of rhodopsin after it is bleached by light exposure, which could contribute to dark adaptation improvement.
What the Research Shows
Bilberry has been evaluated in multiple clinical studies for vision-related outcomes. A systematic review in Survey of Ophthalmology examined 12 controlled studies on Bilberry and visual function, finding evidence of improvements in several visual parameters including contrast sensitivity, glare recovery, and visual acuity in several studies. Results were not uniform across all trials.
Studies on Bilberry and ocular circulation have used laser Doppler flowmetry to measure retinal blood flow before and after Bilberry supplementation, finding measurable improvements in retinal microvascular perfusion. The standardised extract at 25% anthocyanins (typically 80–160mg daily) is the dose most consistently used in clinical research and provides a reliable anthocyanin content.
Products Containing Bilberry Extract
Dosing Guidance
| Use Case | Dose | Frequency | Timing/Notes |
|---|---|---|---|
| Standard | 80–160mg | Once or twice daily | Standardised to 25% anthocyanins |
| Research dose | 160mg | Once daily | Dose used in most clinical trials |
| Note | – | – | Standardisation to 25% anthocyanins is the quality benchmark |
Safety Profile
- Bilberry extract has an excellent safety profile with no significant adverse effects at standard doses in clinical trials.
- Blood thinners: Anthocyanins have mild antiplatelet effects, monitor if taking warfarin or other anticoagulants, though interaction risk is low at supplement doses.
- Blood sugar medications: Bilberry may have mild glucose-lowering effects, monitor if taking antidiabetic drugs.
- Diabetes surgery/procedures: Mild blood sugar effects suggest monitoring around medical procedures.
- Quality matters: Look specifically for 'standardised to 25% anthocyanins', unstandardised Bilberry products may not contain adequate anthocyanin concentrations.
Frequently Asked Questions
Is Bilberry the same as blueberry?
They are closely related but not identical. Bilberry (Vaccinium myrtillus) and blueberry (Vaccinium corymbosum) are different species with similar anthocyanin profiles. Bilberry tends to have more evenly distributed anthocyanins throughout the flesh (giving it a dark purple interior) while blueberries have anthocyanins mostly in the skin. For supplementation, bilberry extract is standardised and consistent; blueberry extract is less commonly used in clinical research.
What standardisation should I look for?
'Standardised to 25% anthocyanins' is the clinical standard. This means 25% of the extract by weight is anthocyanin compounds, a specific quality benchmark. At 80mg of standardised extract, you receive 20mg of actual anthocyanins. Products that list Bilberry without a standardisation percentage may contain variable and potentially very low anthocyanin amounts.
Does Bilberry actually improve night vision?
The WWII RAF anecdote is appealing but not strongly supported by modern clinical evidence. Night vision improvement from Bilberry is inconsistently observed across trials, some studies find modest effects, others find none. The stronger and more consistent evidence is for retinal microcirculation support and antioxidant protection rather than acute night vision improvement.
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