Hi B.,
It all depends on the vitamins that you are giving your children.
Don't throw your money away on grocery store brands.
One a Day's Flinstone, Centrums. They are a waste of your dollars. The vitamins don't make it to your intestines where they get absorbed into the bloodstream.
There is a supplement that is the only one proven to work. And it's guaranteed. If interested, let me know!
I know of a mom using supplements for asthma as little as 3 months old. They broke the capsule in half and mixed in with applesauce or their formula.
I know of another that gave vitamins to their baby girl for kidney infections( 3 a year) That little girl hasn't had a hospital visit in at least 5 years!
God Bless!
J.