Sorry for the delay in responding. Mrs D. - you make a key statement about passive absorption, which agrees with what the specialists told me. You may have not caught this point in my post, but I produce NO stomach acid. Thus, I don't / can't passively absorb the B-12 to the levels that I need. I was told that it obviously couldn't hurt to take oral, just in case a very small amount gets through. I have tried the oral it in all different ways in the last 12 years, at all different doses and varieties, and it has absolutely no impact on my levels. When it comes to the sublingual - I was told that I should try the liquid - not the pill format. That the pill dissolves, as you say, and is simply swallowed. But, that the liquid form, gets partially absorbed directly into the blood. My blood is tested regularly (monthly if not more often) to make sure my levels are up, or we will adjust the shots .... and starting the liquid oral has made a huge and obvious difference. I could barely get it to 500 after 9 months .... and then once I started the oral, it jumped to 800 in 2 weeks, and then over 1000 2 weeks later. Maybe it's just my body - but I'm glad to have found a good combination that seems to work and I'm going to stick with it.