Scurvy is a putrid disease caused by corruption of the body, often promoted by damp, cold, inactivity, and unsuitable food.

Scurvy was one of the great diseases of long sea voyages. Bleeding gums, bruising, weakness, poor wound healing, and death appeared in crews living for months under cold, damp, crowded conditions.

Those circumstances encouraged explanations based on putrefaction of the body, bad air, inactivity, infection, or combinations of environmental hardship and unsuitable food.

Citrus repeatedly provided a clue. James Lind’s 1747 comparison famously found rapid improvement among sailors given oranges and lemons, but a working treatment did not immediately produce a correct theory—or even consistent naval practice.

Only in the early twentieth century did controlled animal experiments establish scurvy as a deficiency disease caused by the absence of a specific dietary factor. That factor was later isolated and identified as vitamin C.

The delay is instructive: evidence that a treatment works can precede understanding of why it works by generations.

Other hardships aboard ships certainly affected health, and citrus was not always stored or processed in ways that preserved its antiscorbutic activity. But the specific cause of scurvy is severe vitamin C deficiency.