BilberryBotanical

• Night visionNot shown to help

  The famous claim, and the one the evidence actively contradicts. It traces to a WWII story about RAF pilots eating bilberry jam before night sorties — possibly wartime superstition, possibly cover for early radar [4].
  
  A 2004 systematic review identified 30 trials, 12 placebo-controlled and 5 randomized: anthocyanosides did not improve night vision in healthy people [6]. The negative results were more consistent in the more rigorous, more recent trials [6]. ^[6]

• Screen-related eye fatiguePossibly helps

  Better supported than the night-vision claim, and much narrower. An 8-week randomized, double-blind, placebo-controlled trial in 281 office workers on video display terminals tested 480 mg/day of extract [11].
  
  Ocular pain, heaviness and foreign-body sensation all fell against placebo (p<0.05) [11]. These are subjective symptom scores, from a single trial. ^[11]

• Ciliary-muscle accommodationPossibly helps

  A 12-week randomized trial at 240 mg/day found objective improvement in ciliary-muscle accommodation after screen tasks, at weeks 8 and 12 (p=0.014, p=0.017) [12].
  
  That is the eye's focusing mechanism measured instrumentally rather than a symptom questionnaire — a stronger endpoint, still one trial. ^[12]

• Diabetic and hypertensive retinopathyPossibly helps

  Small, old, and not repeated by modern trials. A placebo-controlled trial using 160 mg twice daily of a 25%-anthocyanoside extract reported 77–90% improvement on fundus and angiographic findings [18].
  
  A one-year trial at 510 mg/day found contrast sensitivity improving gradually, while its other measured parameters never moved [18]. ^[18]

• NCCIH versus the individual trialsPossibly helps

  ⚠ Two honest readings of the same literature, and we are not collapsing them.
  
  NCCIH's government fact sheet states plainly that bilberry has not been clearly shown to be helpful for any health condition [1]. Several small RCTs — eye fatigue, accommodation, retinopathy — do report statistically significant benefits [11].
  
  The tension is between a cautious overall verdict and positive results in short, small trials. ^[1]

• Leg heaviness and minor venous symptoms — fresh fruitPossibly helps

  The EU's HMPC registers fresh bilberry fruit preparations for discomfort and heaviness in the legs from minor venous circulatory problems, and for capillary fragility [2].
  
  That registration rests on long-standing traditional use, explicitly not on demonstrated clinical efficacy [2]. ^[2]

• Mild diarrhoea and mouth-lining inflammation — dried fruitPossibly helps

  Same traditional-use basis, different preparation.
  
  EMA registers dried bilberry fruit for mild diarrhoea and for minor inflammation of the mouth lining, on the astringent and antimicrobial properties of its tannins [3]. ^[3]

• Blood sugar, and the bilberry-leaf diabetes storyPossibly helps

  ⚠ Bilberry leaf is widely marketed as a traditional diabetes remedy. A comprehensive 2022 review found that indication absent from historical herbal sources before the late 19th century [4].
  
  Clinical results for both leaf and fruit on blood glucose remain contradictory, even though isolated bilberry phenolics show antidiabetic activity in vitro [4]. ^[4]

• Standardized extractThe form used in nearly all clinical research.

  Elemental content

  Typically 25% anthocyanidin, roughly 36% anthocyanoside once the sugar-glycoside portion is counted [19]

  Absorption

  Varies product to product; storage and processing degrade anthocyanin content over time [8]

  Best for

  The form used in nearly all clinical research. WebMD warns a new bottle or a different brand may not behave the same at a nominally identical dose [9]

• Fresh whole fruitEating. It brings fibre and vitamins an isolated extract does not, but no trial has compared the two head to head

  Elemental content

  0.1–0.25% anthocyanoside by fresh weight; about 300–700 mg total anthocyanin per 100 g [13]

  Absorption

  Naturally variable, and far less concentrated per gram than a capsule [13]

  Best for

  Eating. It brings fibre and vitamins an isolated extract does not, but no trial has compared the two head to head [10]

• Dried fruit — tea, decoction, mouth rinseThe EMA-authorized traditional form, for short courses of mild diarrhoea or as a mouth rinse

  Elemental content

  Whole dried berries, no standardization

  Absorption

  Traditional decoction: 5–10 g of mashed berries simmered in water, then strained [13]

  Best for

  The EMA-authorized traditional form, for short courses of mild diarrhoea or as a mouth rinse [3]

• Leaf teaShort-term use only. NCCIH states bilberry leaves may be unsafe in high doses or over long periods

  Elemental content

  1–2 teaspoons of chopped leaf steeped — a different plant part from the fruit [13]

  Absorption

  Not characterized in the sources we read

  Best for

  Short-term use only. NCCIH states bilberry leaves may be unsafe in high doses or over long periods [1]

• Tolerability

  Clinical trials and postmarketing surveillance describe bilberry as generally well tolerated, with mild gastrointestinal effects — nausea, abdominal discomfort [7].
  
  On the liver, LiverTox assigns bilberry a hepatotoxicity likelihood score of E, its lowest: never implicated in a published case of drug-induced liver injury across national registries [7]. ^[7]

• Pregnancy and breastfeeding

  ⚠ The verdict flips depending on which product is being discussed.
  
  NCCIH says little is known about bilberry in amounts greater than food during pregnancy or breastfeeding [1].
  
  Healthline says supplements may not be safe [10]. Drugs.com rates bilberry GRAS as a food, while advising against doses above food amounts [8].
  
  EMA's assessment of the traditional dried-fruit product states it can be used during pregnancy and lactation, with no concern raised about malformation in humans [3].
  
  The workable read: traditional food-like dried fruit is accepted by EU regulators, concentrated extract at research doses is an open question. ^[1]

• Children

  No established safe dose or approval exists for concentrated bilberry extract in children, at any age [2].
  
  The only official pediatric allowance is EMA's dried-fruit monograph, for over-12s, for short courses of mild diarrhoea or mouth-lining inflammation [3]. The fresh-fruit venous product is adults-only [2]. ^[2]

• Bilberry leaf, long term

  NCCIH states bilberry leaves may be unsafe when consumed in high doses or for long periods — a caution that does not apply to the fruit [1].
  
  Multiple sources specify leaf tea for short-term use only [13]. ^[1]

• Allergy — an evidence gap

  A 2021 phytochemistry review states there is no report on the presence of allergenic compounds in bilberry itself [15].
  
  Its close relative blueberry does have rare case reports of anaphylaxis tied to a lipid transfer protein, cross-reactive with peach, apricot and cherry [22]. That risk is inferred from botanical proximity, not documented for bilberry [21]. ^[15]

• Warfarin and other anticoagulants

  LiverTox (NIH/NIDDK) states bilberry may affect platelet aggregation and predispose to excessive bleeding in patients on anticoagulants such as warfarin [7].
  
  A 2020 review in the British Journal of Clinical Pharmacology lists bilberry among supplements that may potentiate warfarin [16].
  
  MSKCC documents one case report of excessive bleeding in a long-term bilberry user newly prescribed a blood thinner [17].
  
  MSKCC advises against combining bilberry with warfarin, other blood thinners, aspirin or NSAIDs — noting the clinical relevance of the aspirin and NSAID part is not known [17]. ^[7]

• How strong is that bleeding evidence, really?

  ⚠ The sources frame the same thin evidence base very differently.
  
  Drugs.com's professional monograph and the 1990 German Commission E monograph describe bilberry fruit interactions as none well documented, or none known [8]. WebMD adds that supplement-drug interactions generally are not fully understood, because the research is incomplete [9].
  
  What the caution actually rests on is a mechanism, one case report, and class caution about antiplatelet herbs. ^[8]

• Diabetes medication

  Bilberry, and particularly bilberry leaf via the myrtillin anthocyanoside, may lower blood glucose [13].
  
  Combined with diabetes medication that is a theoretical additive effect, potentially needing a dose adjustment [13]. ^[13]

Bilberry is eaten as fresh or dried fruit, or made into jam, juice or a decoction — it is a fruit, not a nutrient spread across the food supply.

USDA FoodData Central has no raw bilberry entry, unlike cultivated blueberry, because bilberry is wild-harvested and not commercially grown at scale [15].

A 2021 review reports raw fruit at 14.7 g sugar and 3.6 g fibre per 100 g, plus vitamin C, vitamin K, folate, magnesium and iron [15].

Anthocyanin runs 300–700 mg per 100 g of fresh fruit, among the highest of any commonly eaten berry [8].

No time of day is recommended by any source we checked — NCCIH, the EMA monographs, LiverTox, Drugs.com and WebMD are all silent on it.

Trials that specify a schedule tend to split the dose: 160 mg twice daily in one retinopathy trial, three times a day in the earliest open-label study [18]. That reflects trial-design convention, not a pharmacokinetic reason.

WebMD's guidance is simply to follow the product label, since potency and formulation vary substantially by brand [9].