Sublingual is not absorb in the stomach. That was my problem. Sublingual is absorbed under the tongue. I was skeptical but am so glad to not have to take those shots now. I ask the doc why I needed shots with all the B12 rich food I ate and he told me a lot of people don't absorb B12 from foods after the age of 50.I didnt know they had those but dr said my stomach wont absorb b12 and thats why I have to take shots