My girlfriend saw a doctor about a year ago who told her she has a Vitamin D deficiency. The doctor put her on a very high dose of Vitamin D for a year. She recently went for a test to see how they were and the prescription hasn't had any effect on her Vitamin D levels.
It's something that runs in her family, stemming from her grandfather. Has anyone dealt with anything like this before? She drinks milk, eats cheese, ice cream, etc., but her body doesn't absorb it.