dutch oven is getting discolored on bottom:( is this normal? any way to safely get rid of it

Mary DILS here. Ran out of space
Le Creuset makes a cleaner for the enamel interior. Buy through SUR LA TABLE OR CHEF'S CATALOG. OR
I use COMET SOFT SCRUB WITH BLEACH.
Paint on interior of pan. Let sit a few hours
Repeat as necessary. Wash in dishwasher or very thoroughly by hand
CAUTION. IF THERE ARE ANY CRACKS IN
T HE ENAMEL DON'T USE BLEACH

It is NOT IRON leeching through the enamel. It is discoloration from food cooking
I have lots of Le Creuset and you can get Le Creuset own cleaner made for their enamel pots

thank u! it is enamal and i will use your suggestion with much appreciation!

Is your dutch oven cast iron (like Lodge) or enameled cast iron (like Le Creuset)?
If it's regular cast iron, the brownish spots on the bottom may be rust spots caused by water vapor from a gas range or gas oven. The chemical reaction of burning gas produces water vapor as a byproduct, and if the protective layer of seasoning on the bottom of the dutch oven wears off or burns off, that water vapor can start rusting the metal. It could also be caused by overzealous cleaning, insufficient seasoning, cooking over too high a heat without reseasoning afterwards, cooking very acidic foods, or any number of things that damage the seasoning and allow water to contact bare metal. The remedy is the same, no matter what caused it. First, scour the bottom of your cast iron skillet until the discoloration is removed and the bare metal is exposed: you can do this with steel wool if the spot is minor, or actual sandpaper if it's severe. Then, season your skillet again as if it were brand new, taking special care to treat the bottom: http://www.food52.com/blog/3547_how_to_season_cast_iron
If you have an enameled cast iron dutch oven, then the problem is most likely baked on grease or food gunk. I use Dawn Power Dissolver and a green Scotch-brite pad to remove that.