For centuries, naval planners simply accepted that half a crew might die at sea, and George Anson’s 18th century voyage lost nearly two thirds of its men to a single disease. This episode explains what scurvy actually does to the body: a vitamin C deficiency that collapses catecholamine production, carnitine-driven energy metabolism and collagen synthesis, leading first to depression and lethargy, then to bleeding gums, lost teeth, and old scars splitting open. We also cover the broken GULO gene that leaves humans, guinea pigs and capybaras unable to make their own vitamin C.

The frustrating part is how often the cure was discovered and discarded. Jacques Cartier learned a cedar tea from the Iroquoian people in 1536, James Lancaster ran a rough lemon juice trial in 1601, and James Lind’s 1747 experiment aboard HMS Salisbury proved citrus worked, only for Lind to boil his lemon syrup into uselessness. We follow the British Navy’s adoption of lemons by 1800, the disastrous switch to copper-piped West Indian lime juice, the polar expeditions that exposed the failure, the ptomaine poisoning theory, infant scurvy from pasteurized milk, and the guinea pig accident of 1907 that finally cracked the case.

• Why humoral theory made a lemon cure sound like quackery to elite physicians
• How Captain Cook’s faith in malt wort pushed the real cure back by decades
• Why steamships hid the fact that the lime juice ration had stopped working
• Szent-Gyorgyi, Charles Glen King and the naming of ascorbic acid
• The 10 milligrams a day that reverse scurvy, and who still gets it today