I tend to use a mixture of 50/50 (white with 50% wholemeal) or wholemeal bread for my lo's along with the occasional white loaf.
This is from the babycentre website:
A high fibre diet is not suitable for babies or young children. Occasional use of wholemeal bread, pasta and grains is fine, but too many of them could fill up your child's tummy, not allowing room for other foods. Do not add bran to your baby's food since it prevents some important minerals from being absorbed. Do offer your child a variety of different starchy foods, including wholegrain varieties, but don't use wholegrain foods exclusively until your child is five years old.