Named after the latin scorbutus, scurvy is a very dangerous illness that if left untreated leads to character death. Sailors were known to suffer scurvy on long sea journeys due to lack of fresh fruit and vegetables.
Traveling down deep, dark and damp dungeons can lead to the same lack of fresh food. Bread will become stale, fruit will become over ripe just on the trip to the dungeon entrance and will spoil shortly afterwards. So good supply of vitamin C needs to be ensured so your character's legs don't end up as these:
Yea, I know. It makes rot grubs look like a walk in the park. So players make sure to pack some of these on the following trip.
Just 3 dried orange slices will provide 120% of your characters daily USRDA required amount of vitamin C. They are very easy to make and will preserve for quite some time. The body consumes about 3% of the stored vitamin C per day (http://leda.law.harvard.edu/leda/data/658/Mayberry.html) and consumption will slow down as body reservoirs run low. That means that scurvy will set in between 30 and 60 days. Most surely around 60, but could be less if the diet was initially poor on vitamin C as the body needs 8 to 10 mg of vitamin per day.
Symptoms can be broken down into four stages. Each successively more dangerous to the adventure.
- Abnormally lazy and sudden fatigue. Muscle ache in legs and lower abdomen.
- Gums swell, itch and will bleed under pressure. Teeth may become loose at the roots and actual joint and muscle pain will be felt.
- Gums become putrid and begin to smell like rotten flesh. Gum bleeding will occur. Flesh will become gangrenous and spontaneously bleed. Skin will develop ulcers, particularly in legs and feet, which will become gangrenous. There will be severe muscle and joint pain.
- To cut it short: death.
As a GM keeping tabs on food might be an administrative nightmare, but also open up options for adventure and treasure too if you concentrate on the concept and not so much on the actual amounts. For starters any creature in the dungeon that can't metabolize vitamin C will need a source for it. This may create interesting environments in which dungeon dwellers cultivate special mushrooms or plants. Maybe that's a weak point for a tribe of creatures found deep under the earth. Hit their food supply instead of hitting them directly. Or distract them with an attack on those plants as a way to take them off guard.
It might also set up a small side adventure in the dungeon as the party loses its pack of orange slices and has to retrieve it, go find an alternative source of vitamin C or risk having to turn around and head back to the surface. Remember the clock is ticking and your character is eating up the reserves at a rate of 3% per day.
Dried orange slices can be a great bargaining chip in negotiations. Equally important in long dungeon crawls as in long sea or overland journeys (and steampunk balloon trips!). Deserts, wastelands and frozen tundra provide very little fresh fruit and vegetables. The party may meet a traveler or group of travelers willing to give information or help in return for fresh fruit or a cure for their scurvy.
As an inspiration for magic items there's room to get creative. A never empty lemonade waterskin. Or never ending orange slice which regenerates every night as long as you don't finish it all in one day.
Scurvy was historically a limitation to long sea journeys and its cure was not found until early in the 20th century although work arounds were available in the 19th century. In the medieval setting of D&D scurvy can be woven into the campaign in many ways. As part of the adventure as show above or as an advantage an armada has over another. A whole adventure can be created around the idea of having your party go out and figure out how the threatening army manages to sail for so long without any illness. Is it some secret spell? A magic item? Or arcane knowledge and potion making?