For decades, nutritionally oriented practitioners have recommended Vitamin B12 to patients with neurological problems such as brain fog, fatigue, and sciatica. Even if the patient says it is helpful, other doctors may say the treatment is unnecessary if blood levels are normal or high.

     A recent article illustrates why administering Vitamin B12 despite normal blood levels may make sense. It describes a patient who suffered from trouble speaking and balance problems, both of which can be caused by severe Vitamin B12 deficiency. However, her blood levels of Vitamin B12 were normal. 

     The researchers then used a new testing method, phage immunoprecipitation sequencing, looking for autoantibodies that might explain her illness. They found an autoantibody targeting a receptor that transports Vitamin B12 across the blood-brain barrier and into the tissues of the central nervous system. They then tested her cerebrospinal fluid and found “nearly undetectable” levels of Vitamin B12. She then received very high doses of Vitamin B12, as well as medications to suppress her immune system. With that, she improved substantially.

     Then, the researchers found that 6% of “healthy” controls have this autoantibody. The incidence was even higher in patients with known autoimmune illnesses affecting the brain, such as lupus with neurologic involvement.

     These results show that people with normal Vitamin B12 blood levels can have trouble moving Vitamin B12 into the brain, causing neurologic issues. Rather than ordering an expensive laboratory test (if it is even available), I think most practitioners will simply try Vitamin B12 since it is inexpensive and safe. This article helps me feel comfortable continuing it if it is helpful, regardless of blood levels.