B12 deficiency is more common than you might think
Xin Y, Xu F, Gao Y, Bhatt N, Chamberlain J, Sile S, et al
This process is irreversible and can only become more marked in the future
Typically, a more significant decrease in appetite is seen between weeks four and eight, especially as the dose reaches the optimal maintenance level
The enzyme DAO is produced in the intestine so any impairment to the intestine could result in a lack of the DAO enzyme impairing histamine breakdown
Anecdotal reports describe pattern recognition and verbal fluency gains within 2-4 weeks at 5-10 mg subcutaneous protocols, but this is user-generated, not evidence