Corrie had managed to get a bottle of Davitamin oil from the Red Cross when she and Betsie were being held at the prison in Scheveningen (Chapter 12).  When the sisters were transferred to Ravensbruck, Corrie managed to smuggle the vitamins in with them.  In Ravensbruck, Corrie's inclination was to hoard the precious nutrient for Betsie, whose health was very fragile.  But there were so many others who were weak and ill as well; "it was hard to say no to eyes that burned with fever, hands that shook with chill".  Corrie tried to save the vitamins for only the very weakest, but even then, she was doling out the drops to sometimes more than twenty-five women a day.

Miraculously, no matter how many people Corrie gave the drops to, "every time (she) tiltled the little bottle, a drop appeared at the tip of the glass stopper".  She tried to hold the bottle up to the light to see how much liquid remained, but the dark brown glass was too opaque for her to be able to tell.  Betsie, with unwavering faith, likened the situation to an incident in the Book of Kings in the Bible, when the widow Zarephath gave shelter to the prophet Elijah, and found that her jar of meal and bottle of oil never ran out.  While Corrie tried to explain the mystery with logic and scientific musings, Betsie urged her just to "accept it as a surprise from a Father who love(d) (her)".

Eventually, a young Dutch prisoner named Mien, who worked at the hospital, managed to secure some yeast compound vitamins for the women.  From that night on, "no matter how long (she) held (the bottle of Davitamin) upside down, or how hard (she) shook it, not another drop (of liquid) appeared" (Chapter 13).