Question about Nutrients

On another message string a poster said her vet advised adding a very small amount of meat tenderizer to her dog's food to change the scent and make her poo unappetizing to her. The reason why it smelled like food was that all the nutrients weren't being absorbed. Once again this forum has given me a possible solution to a problem my Molly has. She does the same thing with her poo sometimes. Good to know that there's something I can do to stop her eating it that won't harm her. Is there any particular reason why our sweeties don't absorb all the nutrients in their food? Molly came in off the streets and I rescued her and the pups from the shelter that was going to put them all down. Could she need vitamins or supplements? If so, what kind?