There is substantial international variation in recommended vitamin C intake levels. In the United States, the recommendation is 90 mg/day for men and 75 mg/day for women, while in the United Kingdom (UK), the current recommendation – established in 1991 – is only 40 mg/day for adults. This UK level was based on the 1953 Sheffield study, which found that 10 mg/day prevents scurvy, with 40 mg/day chosen as the recommended level for yielding somewhat higher plasma levels. In this commentary, we argue that the UK recommendation overlooked key evidence available at the time. Specifically, at least six controlled trials published before 1991 reported benefits from vitamin C supplementation in participants whose baseline vitamin C intake was already 40 mg/day or higher. One randomized controlled trial, published in 1993, found benefits from vitamin C supplementation even at a baseline intake of about 500 mg/day; however, this trial involved ultramarathon runners, and the findings should not be broadly generalised. Nonetheless, such results challenge the assumption that 40 mg/day is universally adequate to maintain full health. We also highlight that the UK recommendations were narrowly focused on preventing dermatological symptoms of scurvy, despite strong evidence – even at the time – that vitamin C deficiency can also cause cardiac dysfunction and greater morbidity due to respiratory infections. We conclude that the current UK vitamin C recommendation should be re-evaluated in light of controlled trial evidence and broader clinical outcomes.