D.B.
Actually, that's not the best way to do it. Dannon just got in a whole bunch of hot water with the FDA for running commercials that their Activia and DanActive brands boost immunity - they had to stop the commercials and they had to pay a huge fine. They made a ton of money of their products before that, however. Now they are only running commercials with Jamie Lee Curtis saying the products taste good!
You need a comprehensive children's supplement manufactured by a top food science company with proven clinical trials and data. It should be a powder that you mix in liquid, not a pill of any sort. Even pre-mixed liquids degrade over time. The Physician's Desk Reference says that pills are not absorbed. The AMA says that every single person in the US must supplement because our diets are deficient even if we "eat right" - depleted soils, processed foods, pollution, and so on. It's not a single ingredient - that's how people usually treat these things - "Oh, I need more Vitamin C" or "more calcium" - but megadosing with a single nutrient has been debunked as useless at best and sometimes even harmful.
My family has not been sick in 3 years - not a cold, not a flu, nothing. If you'd like more info, let me know. It takes a little education but there are thousands of kids doing better than yours is - you can make yourself and your daughter a lot happier!