a mix of white and wholegrain products (bread, pasta, rice, etc) is ok but a fully wholegrain diet isnt recommended until the age of 5. I used wholemeal bread but white pasta and rice for my 2. Wholegrain products can fill them up too quickly and can stop nutrients being absorbed.
She'll digest it just fine but if she eats an exclusively wholegrain diet then the large amounts of insoluble fibre may fill her up and stop her eating more of the calorific and nutrient dense foods she needs.
As an occasional thing I doubt it will be a problem, we have brown rice, bread and pasta from time to time mainly because I'm hoping DD will eat wholemeal foods happily in the future (I am aware that this may not work).