My observations.

Daddy and I learnt a lesson this week. We have decided to experiment and spoil our little princess a little with a bit of gluten. She has been such a good girl and it just breaks our heart as she repeatedly request for the forbidden food. On Sunday morning we gave her a quarter of a small bun, and at night, she had a small bowl of noodles. Joy was so happy and really seem to enjoy the food. We were wary of any changes in her behavior, but observed non that is immediate.
How wrong we were! She started looking tired yesterday, and had fever last night. It might be unfair to blame gluten for this, but, this is the second time. The first time was when we purposely ignore the very small amount of gluten she consume over a period of one or two weeks. But it all add up and she got sick.
I read in the newspaper last week on families who chose to be on gluten free diet for better health. I think this is true in Joy's case. Her body could be allergic to gluten and she gets sick easily. Before she was on the diet, I have always observed that she will get fever the day after or the week she consume crackers. She will have sore throat and constipation too.
As for casein, I think it affects the brain and her behavior. I have never dared to purposely provide her with casein because we will usually see instant changes in her behavior. The last time she accidentally had a bite of French fries 'contaminated' with mayonnaise, she laughed non stop for the rest of the day. There is no way to make her stop laughing. Even when she did, she would have smile all over, which is very unnatural.
I can feel that implementing the diet will be harder as she grow older. I can only pray that God will strengthen our determination and help us to teach my princess to understand the importance of this diet and it's effect on her.