You must maintain Vitamin C in your diet or be subject to deadly Scurvy.
What causes scurvy?
The primary cause of Scurvy is insufficient intake of vitamin C (ascorbic acid). This may be due to ignorance, famine, anorexia, restrictive diets (due to allergies, food fads, etc.), or difficulty orally ingesting foods. Historically, scurvy was the result of long sea voyages where sailors did not bring along enough foods with vitamin C...” MedicalNewsToday.com
http://www.culinaryanthropologist.org/recipe%20pdfs/Preserved%20lemons.pdf
I have this on hand for everyday use but, did not know the extreme value. It takes 30 days to cure the citrus. Any citrus will work ie, lemons, limes, grapefruit, oranges etc.
Cole crops, cabbage, are a good source of vitamin “C”