Scurvy

Scurvy was a naturally occurring form of disease, what some classified as a deficiency or nutritional disease. It was common among adventurers who tried to subsist on only rations and among sailors.

The best method for preventing or treating scurvy was to eat certain fruits, in particular citrus fruits, though onions could also help. Salbread was another popular choice among sailors, due to having lemon and orange peels baked into the bread.