Bilberry, a close relative of the American blueberry, has grown wild across Northern Europe for millennia and been used in regional folk medicine for digestive and circulatory complaints. Its most famous modern association, however, comes from World War II: British Royal Air Force pilots reportedly ate bilberry jam before night missions, crediting it with improving their night vision — a story that entered popular culture and cemented bilberry's reputation as a vision remedy.
That wartime story is, itself, part of the honest evidence picture: some historians note the RAF may have circulated the bilberry story partly as cover for a real advantage they didn't want revealed — early radar technology. Whatever the origin of the legend, it drove decades of subsequent scientific interest in testing whether bilberry's anthocyanin compounds actually improve night vision.
Bilberry's flagship traditional claim — improved night vision — does not hold up well under rigorous modern testing. A systematic review of 12 placebo-controlled trials found the 4 most recent and most rigorously designed randomized controlled trials were all negative for night vision improvement in healthy people. A fifth trial and seven non-randomized trials did report positive effects, but reviewers noted these used less rigorous methodology, and negative results were associated specifically with more rigorous study design. The review's direct conclusion: the hypothesis that bilberry improves normal night vision "is not supported by evidence from rigorous clinical studies."
There is a more modest, separate area of newer research worth distinguishing: small trials on eye fatigue from screen use (rather than night vision specifically) have found some positive results, such as a trial finding reduced eye strain markers in people doing computer-heavy work. This is a smaller, less-established body of evidence than the famous night-vision claim. Given the flagship traditional claim is specifically contradicted by the most rigorous available trials, "Limited" is the accurate rating.
Ripe berries eaten fresh or made into jam; dried berries used for tea; modern research primarily uses standardized extracts.