My old bun was a real fussy eater and had severe molar mollocassion (SP?) having to have treatment every 5 months from when he was very young. He would only eat SS pellets, white bread and dwarf corn. Believe me I tried everything to starvation. Anyway he lived a healthy 7 years. So i guess it asnt that bad for him. I was just grateful Buddy was eating something and enjoyed it so he had about 3 pieces a day for several years.
But it is supposed to be not the best food, so if your bun chomps on everything else its probably best to avoid it if poss or just little treats now and then.