I'm not sure to be honest! I developed it a few months after my daughter was born. Basically your body for some reason will create "autoantibodies" that attack the cells that make intrinsic factor. Once you don't have intrinsic factor, you are no longer able to absorb vitamin b12 and have to do shots to keep your levels up. If your levels of b12 drop too far you can experience everything from memory problems similar to dimensia to neuropathy (numbness) and it would eventually be fatal after 2-5 years.
I do know that it causes your red blood cells to become larger an kind of deformed and most of the other health related side effects, but everything I read focuses on more serious things than hair (must be written by a man
I posted hoping someone else may be on the boards, but since it rare to begin with, and then 80% of people with it are over 60 I know my chances are slim.
I had noticed that the supplements geared toward hair skin and nails all have high amounts of b12 and I didn't know if the levels actually affect your hair. Mine is much dryer and curlier than when I was younger, but I know pregnancy really changes your hair too.
Maybe someday, someone that has it, or better knowledge of it than me will post
Thanks for asking and responding! And make sure if you ever take an antacid like zantac or tums long term you take a high dose b12 supplement because they cause your body to absorb almost no b12 and you can get all the pernicious anemia symptoms without having the actual disease