I would be tempted to ask her (the MIL) what her own mother and grandmother used to have in the time before Benecol and other margarines and to ask the nurse if she actually knows how spreads are made and what with. Mind you, I would also be tempted just to throw in a factoid about how half of all NHS staff (including admin, consultants and porters etc) are overweight or obese so are themselves unhealthy by their own standards. Physician heal thyself an' all that jazz.