I'm not sure, but I read somewhere that eggs do give protein-like effects, but it doesn't last long because the molecules(?) are too large to penetrate the hair strands. I've tried it, and I like the effects it gave my hair, except for the smell and that even though I use the coldest water to rinse it off, I still have white cooked bits stuck in my hair. Ew. Though I don't think it hurts to try it for a temporary effect.
Have you heard of iAgirl's gelatin protein treatment? I heard that it can actually penetrate and it works for me, though I went a bit overboard... But that's a different story.