Vitamin C and scurvy: a cure ignored for 200 years

In 1747, Royal Navy surgeon James Lind conducted one of medicine's first clinical trials, dividing 12 scurvy patients into six groups and testing different treatments. Those given citrus fruit recovered in six days; others on vinegar, seawater, and cider did not. His results were ignored for 42 years — until the Navy provisioned ships with lemon juice in 1795 and nearly eliminated scurvy entirely. The reason for the delay was partly bureaucratic inertia and partly that the mechanism was unknown: vitamin C itself wasn't isolated until 1928.

Source: Lind, A Treatise on the Scurvy (1753)