We give DD both a multivitamin and probiotics. There has been some discussion in pediatric journals and magazines about an increase in immune strength for kids taking probiotics. We give DD Metagenics Ultraflora Children's probiotics... They chewable so it makes it easier for her to take. The multivitamin that we give her also has a greens supplement, because she isn't that great about eating her veggies or different kinds of fruit. Unfortunately, the multi is from a Canadian company so I'm not sure how easy it is to get them... progressive nutritional multivitamin for kids.