Interesting question about which is best, breast milk for the first six
months followed by formula only, or a mix of the two for a whole year.

I vote for exclusive breastfeeding for the first six months, followed by
formula for the next six months.  This would help the gut and brain mature
better than a mix from the beginning, and be more likely to ward off
allergies. The baby will have a better chance of developing for the first
six months than on mixed feeding.  And I'll bet a mother who exclusively
breastfeeds for six months will decide she can continue to breastfeed when
that magic date comes along.

The mom who starts off mixed feeding will probably soon find herself with a
diminsihing milk supply and end up only formula feeding from six months on
anyway.  And formula from the beginning leads to different gut flora,
possibility of allergies and colic, greater chance of gastro-intestinal
infections which are more dangerous for a young infant, etc.

Kathy Dettwyler, Ph.D.