Unfortunately there is a widespread misunderstanding on the internet which causes a lot of confusion, but here is no aluminum in baking soda ( bicarbonate of soda), only in baking powder!
I use Arm and Hammer baking soda all the time internally.
Here is a link that explains it, but you can also do a google search. http://preventdisease.com/news/14/111814_Once-And-For-All-Baking-Soda-Does-Not-Have-Aluminum.shtml