We live in a world of nutritionally depleted foods. My daily recommendations are a multi-vitamin, Vit D3, and probiotics. If you don't know much about probiotics I highly recommend you do some research. They are entirely safe even for infants but, not all probiotics are the same, so make sure the ones you get have a guaranteed potency to it's expiration date on the bottle and not just a guarantee from the date of manufacture. There's a big difference.
Just from my experience, I can tell you if your child is throwing up and you give them probiotics, they will stop! COOL huh!!! You'll probably have to try it to believe it, I know I did.