People have, for centuries, fed their hens on household scraps.
This was not always a balanced diet & therefore the laying may have been affected. I think that, provided the chickens have unrestricted access to a balanced diet (most easily delivered as layers pellets or mash, a little bit of almost anything is no bad thing as it adds variety to their lives.
However, it needs to be in proportion to the number of birds...... a spoonful for a couple of chickens, a bowlful if there are 50.....