Hi Y'all;
I'm certainly not an expert, especially with chemistry, so I'll just bring up a little about what I'm learning from observing people's posts and some case studies I've read.
Although many of us have learned this here, I'll repeat it again,because, not only is it repeatable, but it also helps me in my own process when I repeat it.
The co-factors that Rich and Freddd suggest to us in the methylation protocols, particularly Folate, aid with the bioavailability of B12. They are important companions.
Also, many people find that they feel better with subcutaneous injections of B12 over intramuscular ones. Even though B12 is water soluble, it seems that injecting it into fat helps to modulate the delivery,certainly by slowing it down. But also there is some evidence that fatty acids may help with the bioavailability of B12.
There are various fats that are suggested in the protocols here, such as lecithin, etc. I would also suggest that the fatty acids found in coconut oil and butter may also be considered, as they may help absorption. They prime the cell membranes in a way that makes them more permeable to nutrients. B12 is such a big molecule, it needs alot of help getting into cells.
There is a chemical compound called SNAC, an acronym, that has been used recently, to enhance the availability of B12. Maybe the chemistry scholars here can understand it's actions. All that I've been able to gather from it is that the C in the compound stands for Caprylate, Caprylic acid, found in foods such as butter and coconut oil.
Although I've been generous to myself with these foods, especially in recent years, I still easily become B12 deficient if I don't take 10mg.s or so of Mb12 subs. daily. But I suspect that these fats may be helpful along with the cofactors discussed here.