Overview
Eye/circulatory support via anthocyanosides/anthocyanidins (vascular permeability, microvascular blood flow); astringent tannins in dried ripe fruit used for diarrhea and mouth/throat mucosa irritation; topical use for mild mouth/throat inflammation. Leaf extracts discussed historically for reducing glycosuria and postprandial hyperglycemia (text notes this leads to diabetes-related contraindications).
Plant family
Ericaceae
Parts used
Fruit (berries) and leaves
Actions
Astringent · Tonic
Affinities
Cardiovascular · Digestive
Body systems
Cardiovascular · Digestive
Taste profile
Faintly bitter and astringent
Tissue states
Traditional use
Used for degenerative retinal conditions, varicose veins, atherosclerosis, venous insufficiency, hemorrhoids; historically used for night vision (though evidence suggests less effect than believed).
Current use
Eye/circulatory support via anthocyanosides/anthocyanidins (vascular permeability, microvascular blood flow); astringent tannins in dried ripe fruit used for diarrhea and mouth/throat mucosa irritation; topical use for mild mouth/throat inflammation. Leaf extracts discussed historically for reducing glycosuria and postprandial hyperglycemia (text notes this leads to diabetes-related contraindications).
Preparation
Dried ripe berries; decoction; leaf tea; fluid extract; standardized extracts used in studies (per course text).
Dosage guidance
Dried ripe berries: 20–60 g (0.7–2 oz) daily. Decoction: 5–10 g (1–2 tsp) mashed berries simmered 10 min in 1 cup/236 mL water; used topically as well. Leaf tea: steep 1 g (1–2 tsp) finely chopped dried leaf in 150 mL boiling water 5–10 min, strain. Fluid extract (1:1): 2–4 mL (0.5–1 tsp) 3×/day. Avoid using leaves >3 weeks continuously.
Cautions & contraindications
Bilberry leaf may lower blood glucose and affect triglycerides/lab tests; avoid with diabetes/insulin therapy per course text; monitor closely if combined with antidiabetic drugs. Avoid prolonged/high-dose oral leaf use; text warns death can occur with prolonged use of bilberry leaf at 1.5 g/kg/day. During pregnancy/lactation: fruit in food amounts considered likely safe; oral leaves not recommended due to potential toxicity. Caution with anticoagulants (coumadin/warfarin/Plavix) due to platelet aggregation effects noted in research; also caution combining with other glucose-lowering herbs (devil’s claw, fenugreek, garlic, guar gum, Panax ginseng, psyllium, Siberian ginseng).
Evidence notes
Active constituents in berries: anthocyanins (delphinidin, cyanidin, petunidin, peonidin, malvidin glycosides), quercetin-3-glucuronide, hyperoside; plus catechins, tannins, pectins, vitamin C. Leaves: quercetin + glycosides (hyperoside/hyperquercitrin) plus phenolic acids, tannins, iridoids; text notes chromium content and glucokinin/neomyrtilline discussed as glucose-lowering factors. Mixed evidence on night vision; some evidence on platelet aggregation and retinopathy outcomes.