I'm reading the 2nd ed. of "Could It Be B12?" by Sally M. Pacholok, R.N., B.S.N. and Jeffrey J. Stuart, D.O. and really recommend it. B12 is a very important, water-soluble (you pee out what you don't need) vitamin and it's ONLY found in animal products. So imagine how critical it is for our carnivores? To quote the book, "B12 wears many hats, playing key roles in the health of your nerves, your brain, your blood, your immune system, as well as in the formation of DNA . . . " This vitamin is absorbed in the small intestine, so IBD kitties in particular may benefit from supplementation since they may not be absorbing what they need from their food. Finnlacey has information on her site, ibdkitties.net. Cats that develop diabetic neuropathy may also benefit from B12 supplementation (see this fascinating story about Jasper:
http://laurieulrich.com/jasper/).
Here's something else I find interesting: "Toxins such as mercury interfere with B12's ability to cross the blood-brain barrier and reach the neurons where it's needed." Which leads me to wonder if every time our cats get vaccinated (other than Purevax, which I think doesn't contain mercury, but not 100% sure), the vaccine is preventing the B12 from getting to our kitties' brain? The book does mention (regarding pediatric immunizations/vaccinations) to avoid such products containing mercury, or "Using high-dose B12 pre- and post-vaccination may be another option." Now remember, this is about human children, but I wonder if this could also apply to cats.
I hope this helps! Thoughts? Comments? Wise cracks?