M.H.
You might try adding fish oil to her diet. Both the Carlson's brand and Nordic Naturals are great brands that are very low in PCB's, heavy metals, and products of oxidation. When my dd was that age, I would get a bottle and add a bit to applesauce. The applesauce covered the taste and texture, and she did not mind eating it at all.
It has the DHA that is so important for growing brains, and other good, Omega 3 fats.
Good luck!