Perhaps even more than all of these issues was scurvy. It killed absolutely ridiculous numbers of sailors all the way to the 19th century. Funny thing about it

Perhaps even more than all of these issues was scurvy. It killed absolutely ridiculous numbers of sailors all the way to the 19th century. Funny thing about it too. We now take it for granted that it is caused by a vitamin C deficiency, so it can be prevented by access to fresh citrus fruits. And some had caught onto this, but at the time it was largely considered superstition since it was thought that scurvy was simply a disease, and so trying to prevent it by eating lemons was treated with extreme skepticism. Even once people began to realize that it somehow really worked, the benefit was attributed to the acid somehow interacting with the disease and not to vitamin deficiency. It's interesting how we, now the benefit of hindsight, can take things that took hundreds of years and literally millions of deaths to discover as being practically self evident.