If citrus products prevent scurvy, why did the Royal Navy suffer from so many scurvy outbreaks a century after Lind?

Not all citrus fruits have high amounts of vitamin C. In the mid-1800s, long before Casimir Funk’s theory of vital amines (vitamins), the Royal Navy changed its fruit supplier and started receiving a strain of Caribbean lime that has very little vitamin C. Several polar exploring expeditions used the nonprotective limes and suffered severe losses from scurvy. This led many to doubt the efficacy of citrus fruit in the management of scurvy. After the discoveries of Pasteur and Koch, a paradigm swept through medicine that most diseases were caused by bacteria, either by direct infection or by ptomaine, a bacteria-induced food poisoning. Indeed, several nutritional diseases had their “offending bacteria” identified, including scurvy, pellagra, and beriberi.