James Lind wrote in his A Treatise of the Scurvy (published in 1753):
On the 20th of May, 1747, I took twelve patients in the scurvy on board the Salisbury at sea. Their cases were as similar as I could have them.
Thus began Lind’s description of his classic therapeutic experiment on sailors with the scurvy in which various, then proposed remedies, were tested as antiscorbutics. His report continued:
[The subjects] lay together in one place…in the fore-hold; and had one common diet, viz. water-gruel sweetened with sugar in the morning; fresh mutton-broth often times for dinner;…and for supper, barley and raisins, rice and currants, sago and wine, or the like. Two of these were ordered each a quart of cider a-day. Two others took twenty-five [drops] of elixir vitriol three times a-day, upon an empty stomach…Two others took two spoonfuls of vinegar three times a-day, upon an empty stomach;…Two of the worst patients…were put under a course of sea-water. Of this they drank half a pint every day…Two others had each two oranges and one lemon given them every day. These they eat with greediness, at different times, upon an empty stomach. They continued but six days under this course, having consumed the quantity that could be spared. The two remaining patients, took the bigness of a nutmeg three times a-day, of an electuary recommended by an hospital-surgeon, made of garlic, mustard-seed, [horse-radish], balsam of Peru, and gum myrrh…
The consequence was, that the most sudden and visible good effects were perceived from the use of the oranges and lemons; one of those who had taken them, being at the end of six days fit for duty… The other was the best recovered of any in his condition; and being now deemed pretty well, was appointed nurse to the rest of the sick.
Cider, Lind reported, had the next best effect. There was no remarkable alteration of the course of the disease in any of the other patients at the end of the two weeks’ tests. Although he does not mention them in the quotation above, Lind had a control group — all the other patients on board of his ship. These patients did not get anything that might cure their disease — all they got was a pain-killing paste (“lenitive electuary”), a laxative (cremor tartar), and/or a cough syrup (“pectoral”). It is clear that these products can have an effect on the symptoms (pain, constipation) but will not cure the disease. Thus, Lind’s experiment provided clear evidence of the curative value of oranges and lemons and was also the first example of a controlled clinical trial using human subjects.