Was told, by a greyhound man, it takes out the goodnes off the food.
Personally, i think, if you find a good balanced deit for your runner, that benifits it the right way, then stick to it. If they look fine on it and are not having any ill effects, dont be listening to others about whats best ect, its one of the down fauls of many dog men, choping and changing everytime one of them tells you whats best to feed ect. Bit like that harry Enfeild character, ''you dont wana do it like that, nooo, you wana do it like this!!!!!''
Good advice there id say if its working for them and h