The quotations remind me of many references that have not been updated for many years. Of course, the context may tell a different story, but I believe they are operating on the assumption that everyone who is B12 deficient has anemia (megaloblastic or macrocytic anemia wrongly referred to as pernicious anemia). That would mean that some of the people they are referring to have become extremely fragile, and depending on how they have tested the subjects, some may be B12 deficient even though the docs think it has been ruled out.

Regardless, since folic acid is added to many foods, and since malabsorption of B12 from foods becomes quite common as people approach and pass middle age, B12 deficiency is more likely and extremely damaging. Also, because B12 deficiency is very likely to go undiagnosed by ignorant physicians (most on this issue), a person would be statistically far safer to take their 1000 mcg B12 and separate B complex at another time of day than wait to be diagnosed.

Unless a person has some other problem, the likelihood of serious consequences of brief low potassium due to B12 treatment is almost surely because B12 deficiency has been untreated far too long. And I have yet to see anything that convinces me a person would experience a potassium dip if they didn't need the B12. I'm open to any credible information to the contrary.

As suggested here often, when people have serious symptoms and begin B12 treatment, it is a very good idea to make sure potassium-rich (brief dip in potassium when beginning to get the needed B12) and iron-rich (longer heavy draw on iron stores when the body works on repairs) foods are eaten and a B complex taken.

It is also a very good idea to insist on a ferritin test. If iron stores are high, of course a person would not want to eat a lot of iron-rich foods and would certainly want to avoid anything fortified with iron, Most docs will not order the ferritin test unless the patient asks, and high or low iron often goes undetected because the more common and less sensitive tests are relied upon. Those common test results can be smack down the middle of the "normal" ranges while a patient is low or high in iron and/or B12.

rose