At any given time around the world, millions of people are involved in clinical medical trials. The exact number of people involved isn’t known; one statistic to note, though, is the NIH’s ClinicalTrials.gov registry of over 202,000 trials.

Such clinical trials are relatively recent in the history of medicine. The first modern clinical medical trial was published in The British Medical Journal in 1948. This was a randomized controlled experiment that showed that the bacteria that causes pulmonary tuberculosis became resistant to the antibiotic streptomycin.

This streptomycin trial had an important precedent two centuries earlier when the British navel surgeon James Lind figured out that citrus fruit could treat scurvy. Scurvy is caused by a deficiency of Vitamin C, also known as ascorbic acid. People on long sea voyages and polar expeditions, without access to fresh vegetables and fruits, were highly susceptible. And, in fact, it took the lives of more British seamen than warfare in the 18th century.

As C.C. Lloyd tells the tale of the “conquest of scurvy,” there were strong hints before Lind. Jacques Cartier’s crew in 1535 were cured with native American spruce beer. In 1617, the first manual of nautical medicine said lemon juice was a “precious medicine and well tried.”

But a lot of people didn’t get that memo. The disastrous 1740-44 expedition of Commander George Anson, in which most of his men died from scurvy, inspired Lind to test different diets and medicines. He fed six pairs of scurvy-ridden sailors different regimes. The two lucky enough to get two oranges and a lemon daily were fit for duty in six days. The rest died.

It wasn’t quite the eureka moment, though. (And the ethics of it would raise some eyebrows today.) Lind published his big book on scurvy in 1753, but the hidebound British Admiralty would have nothing to do with the results until 1795; the merchant navy held out until 1867. Even later, polar expeditions didn’t take the citrus-juice-proof to heart, with the result that many explorers met an unnecessary death on the ice.

A medical trial is one thing. Getting it publicized is another. And changing people’s minds as a result is yet one more thing, perhaps the hardest of all. Lloyd even wonders if Britain would have won the American War of Independence if the benighted Admiralty had listened to Lind decades earlier. That seems unlikely, considering the British Navy so vastly out-classed the start-up American navy, but it sure would have saved the lives of many more sailors.