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Vitamin B12

Vitamin B12

Research: Are more people deficient in vitamin B12 than we think?


Most doctors think about testing your vitamin B12 levels if you have neurological symptoms such as tingling, numbness, or burning sensations in your arms or legs, weakness, or loss of balance.  They may also think of testing it if your red blood cells are large, to see if you have a type of anemia called pernicious anemia.

However, in the past decades, newer research has shown that many other symptoms or illnesses have been associated with low levels of this crucial vitamin.  These newer associations include cold hands and feet, tiring easily, bruising easily, low blood pressure, incontinence, anxiety, depression, and poor cognitive/mental function – e.g.: poor memory, and even seizures.

In fact, the usual (and most common) way to test your levels of vitamin B12 has been through your blood, to literally test the level of B12 in your blood.  However, this method of testing has proven not to be very predictive of the actual levels in your body, or what is actually available in your tissues and cells.  Instead, a newer and much more accurate and sensitive way to test your functional level of tissue-containing B12 is through a specific marker called methylmalonic acid, or MMA.  This is a substance that builds up in your blood or urine if there isn’t enough functional vitamin B12 in your tissues.

This research link indicates that the MMA test would be a more effective way to determine earlier vitamin B12 deficiency.


Another 2009 research link (below) refers to a person who developed significant brain and spinal cord neurological damage, due to delayed detection of vitamin B12, having relied on the standard method of serum vitamin B12 testing:  It makes you wonder how many people are suffering with such profound neurological damage due to outdated methods of testing.  This last reference also relates to how methylmalonic acid can help predict decline in cognitive function in an elderly population.

In my naturopathic practice, I suspect a vitamin B12 functional deficiency in about one-third of my patients.  Often, I use a B12 ‘challenge’ test, where I give a 1000 microgram intramuscular injection of preservative-free vitamin B12, and wait up to two days for a response.  Often, patients will tell me that their energy improved, they slept better, their mind felt a bit sharper, or some other specific improvement.  Usually you would need a few injections to correct the deficiency, to notice a lasting improvement.

Vitamin B12 is a fascinating essential factor in our health.  It is likely that many people are low in this vitamin, but are not aware of it themselves, or to their doctors.  In time, I expect the methylmalonic acid test will likely replace the serum vitamin B12 test, as a more accurate method of testing vitamin B12 levels.

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