A study out in the journal "Pediatrics" says the right amount for small kids is two cups and not more, but then her mother noticed she was getting pale and napping when she shouldn't.
Turned out Grace was drinking too much milk and that can cause a tug of war of sorts between two essential nutrients.
The more milk children drink, they store more vitamin D but less iron.
Low iron levels can lead to behavior problems and difficulties with school lasting into adulthood.
So to prevent this, make sure kids get no more than two cups of milk a day.
If they can't drink milk, nutritionists suggest almond milk or vegetables as vitamin D supplements.