The more I research, the more I believe parasites can be a big cause for B12 deficiency. Most doctors never consider this. If they do, they might run the 3 day stool test which is notoriously inaccurate.
I never really realized that parasites can not only be in the gut but also the organs, muscles, eyes, and brain. Prescription drugs for them can drive them deeper.
We all have parasites to greater and lesser degrees. If you've ever traveled, had pets, eaten undercooked fish or meat, gone barefooted, or had food poisoning, among other things, you're at greater risk.
I'm using herbal treatment along with a frequency machine and it's been quite fascinating to see the die off. From what I've read, it's important to be dedicated to treating them for a year because of the life cycles. Also very important to treat all pets in the home as well.
youtube.com/watch?v=ZkEhY02...
iloveiodine.com/symptomspar...