We have the same problem here. I'm determined not to stress out about it. As long as he is eating relatively healthy food (sultanas, sandwiches, grapes and avocado is about it!) that's ok with me.

Hun, I know it's frustrating but try not to make food a stand off point or a battle ground. If you're really worried, get a multivitamin for him. He will come around to eating a much wider variety of foods in his own time, as long as they are available and offered to him from time to time.

HTH.