"B-12 is also unusual in that it is dependent upon a second substance, called intrinsic factor, to make its way from the "GI" tract (gastrointestinal tract--the stomach and intestines) into the rest of the body. Without intrinsic factor, which is a unique protein made in the stomach, vitamin B12 cannot gain access to the rest of the body where it is needed."
http://www.whfoods.com/genpage.php?t...rient&dbid=107
That's why the shots are so good.