symptoms of low vitamin b12 deficiencyvery low b12 symptomsb12 deficiency low blood pressuredeficiency in b12 symptomslow b12 symptoms nhslow b12 neurological symptomslow vitamin b12 symptomssymptoms of low b12 in elderlysymptoms of low b12 and folatelow b12 levels symptomssymptoms of low iron and b12low vit b12 symptoms