I've borrowed this from the PAS forum, having raised issues of potential B12 deficiency on several past posts.
Might be worth a read for anyone who suffers fatigue as PA & B12 deficiency are a common cause, as are any other micronutrient deficiencies. The rest of the journal is interesting too.
I'm unable to copy & paste the Open Access Government text due to the format.
edition.pagesuite-professio... page 66~67.