Question

You advise your grandmother against using mineral oil as a laxative because

Answer 1

The human body, as you may know, requires vitamins and minerals to be healthy.  Also, laxatives can be more hurtful than helpful sometimes.  So, it is important for everyone, especially older people, to be careful with laxatives and be very aware of their uses, side effects, and interactions.  Mineral oils will cause everything to be passed/excreted.  This includes fat soluble vitamins.  Thus, it would be quite advisable to let your grandmother know that even though mineral oils might help with constipation, there will be side effects—side effects that may do more harm than good.