Dear Dr. Roach: My 90-year-old mother lost her sense of smell several years ago. We think it was related to a new medication. I read that vitamin A deficiency can be responsible for this, and I have reason to believe she has a real deficiency. She also has poor night vision, dry eyes and skin problems.

Her doctor nixed the idea of taking any quantity of vitamin A or beta carotene. I am perplexed. Can you think of any reason why she shouldn’t try 5,000-10,000 IU daily for a month or two? Would moderate kidney damage preclude vitamin A in these doses? Is there a test for deficiency?
— M.M.