Welcome to our board. For really small children, I think food sources for magnesium is the best way to go.

The statistics for accidental poisoning with magnesium are highest for small children and the elderly. As it is only about 20/yr, and mostly from misuse of Fleets enemas, but still in a small child one has to be very careful.

this link gives food values...but be careful and watch the quantity/volume stated...:
http://www.vaughns-1-pagers.com/food...sium-foods.htm

The RDA for your child is suggested at 130mg/day.

I think almonds are the easiest to do and are very high. For a small child you can grind them up and sprinkle on cereal or mix into oatmeal.

Edamame beans are very tasty and kids may enjoy taking them apart to eat...sort of a fun finger food. They are buttery and creamy and not beany.
Many kids will eat navy beans and chili..
This food list is good too:
http://lpi.oregonstate.edu/infocente...ium/index.html

You can switch lettuce in sandwiches with swiss chard...it goes in and is easy to eat this way. My husband doesn't even notice! LOL

Taking supplements of magnesium can loosen stools in some people. In a five year old, you really DON'T want that, so that is another reason food sources are better.

There is a cream for topical use:
http://www.kirkmanlabs.com/products/...m_Spec225.html
And you can add some epsom salts into the bath water to be calming that way.
This is a very quick way to calm muscle tension/hyperactivity.