James Lind scurvy while that ship was patrolling the Bay of Biscay. Just after that patrol he left the Navy, wrote his MD thesis on venereal diseases and earned his degree from the University of Edinburgh Medical School, and was granted a licence to practice in Edinburgh. Scurvy is a disease now known to be caused by a vitamin C deficiency, but in Lind's day, the concept of vitamins was unknown. Vitamin C is necessary for the maintenance of healthy connective tissue. In 1740 the catastrophic result of Anson's circumnavigation attracted much attention in Europe; out of 1900 men, 1400 had died,
Scurvy championing the cause of citrus juice, therefore, had no practical impact. Medical theory was based on the assumption that scurvy was a disease of internal putrefaction brought on by faulty digestion caused by the hardships of life at sea and the naval diet. Although this basic idea was given different emphases by successive theorists, the remedies they advocated (and which the navy accepted) amounted to little more than the consumption of 'fizzy drinks' to activate the digestive system, the most extreme of which was the regular consumption of 'elixir of vitriol' – sulphuric acid taken with spirits and barley water,