B12 is a water-soluble vitamin that contributes to red blood cell formation and central nervous system function. Energy production, digestion and absorption of food, respiration, circulation and temperature regulation also rely on this vitamin, which is found in many animal products but is absent from plant foods. Deficiency of this vitamin can cause nerve disorders.
Muscle Weakness
A study published in the February 2011 issue of "Neurological Sciences" reported on a case of vitamin B12 deficiency that caused neuropathy in a strict vegetarian. Vitamin B12 levels one-and-a-half times lower than the lowest recommended values for the patient, a 22-year-old male, caused weakness and numbness in both arms and both legs, elevated kidney enzymes and homocysteine -- an inflammatory marker. Oral and injected B12 supplements led to gradual, though not complete, improvement of symptoms over 14.5 months. Muscle power returned to normal earlier than sensory function.
Optic Nerve
Limited diets due to food selectivity in autistic children may result in a vitamin B12 deficiency and associated neuropathy, according to a study published in the October 2010 issue of "Pediatrics." In the study, autistic children with gradual loss of vision due to optic nerve atrophy were found to have low B12 levels due to an almost complete lack of animal foods in their diets. Treatment with vitamin B12 injections restored vision to normal. Researchers note that food selectivity is a common complication of autism and can lead to deficiency syndromes with potentially serious neurologic consequences.
Sciatica
Sciatica, an irritation of the sciatic nerve, which runs from the lower back down the back of each leg, may be caused by vitamin B12 deficiency, according to a study published in the April 2010 issue of the journal "Experimental Neurology." In the laboratory animal study, researchers demonstrated that B12 supplementation promotes nerve growth and protects nerves from damage. Continuous high-dose B12 supplementation improved nerve regeneration and recovery of nerve function. In the study, authors concluded that high-dose vitamin B12 therapy may be an effective treatment for some nerve disorders and can be targeted to specific tissues.
Hidden Cause
Nerve damage due to low vitamin B12 levels occasionally occurs before levels fall below acceptable values, according to a case report published in the August 2009 issue of "Cases Journal." In this case, a 39-year-old man experienced numbness and difficulty coordinating movement with his hands. At first examination, his blood levels of vitamin B12 were normal. However, a repeat examination revealed extremely low B12 and extensive spinal nerve damage on an MRI. Six months of vitmain B12 injections resolved his symptoms and returned his spine to normal.
References
- "Neurological Sciences"; Serial Nerve Conduction Studies in Vitamin B12 Deficiency-Associated Polyneuropathy; C. Huang, et al.; February 2011
- "Pediatrics"; Vitamin B12 Optic Neuropathy in Autism; S. Pineles, et al.; October 2010
- "Experimental Neurology"; Methylcobalamin Increases Erk1/2 and Akt Activities Through the Methylation Cycle and Promotes Nerve Regeneration in a Rat Sciatic Nerve Injury Model; K. Okada, et al.; April 2010
- "Cases Journal"; Sub-acute Combined Degeneration with an Initially Normal Level of Vitamin B12: a Case Report; F. Makdsi, et al.; August 2009
- University of Maryland Medical Center: Vitamin B12 Benefits:
