Vitamin B12

By G. Douglas Andersen, DC, DACBSP, CCN

In a recent issue of the Back Letter, 11(7):77, 1996, there was a very interesting article about one woman's 14-month saga with leg pain.

Case History

This was the case of a 56-year-old woman with sciatica, unresponsive to conservative care.

She had x-rays, a CT myelogram, and an MRI, which were all essentially negative (the MRI showed a mild bulge at L5-S1). After not responding to oral anti-inflammatory medication, she was given epidural steroid injections. After six months of increasing symptoms, she went to an orthopedic surgeon who diagnosed a piriformis syndrome. There were more steroid injections, but the pain returned. The woman, who had been a regular exercise walker, had pain so intense she was admitted to a hospital. Many tests were done including blood chemistry, CBC, bone scan, EMG, and MRIs to her brain and thoracic spine. All the tests were normal. She was discharged and continued to suffer. One month later a second EMG showed a left sciatic neuropathy with mild polyneuropathy. Her orthopedic surgeon then performed a piriformis release. She had slight temporary improvement and then began to deteriorate once again. In addition to left leg pain, she began to suffer from paresthesias in both arms and her right leg. Additional blood tests showed a mildly low serum cobalamin level.

Laboratory Testing

The most common method to establish B12 deficiency is a serum B12 assay. The Schilling test measures the absorption of radioactive vitamin B12 with and without intrinsic factor. An MCV value greater than 100 can indicate a possible B12 deficiency even before the signs and symptoms of anemia are present. Currently, the most accurate test for B12 assessment is urine methylmalonic acid analysis by gas chromatography and mass spectrometry. It is a very accurate and noninvasive way to establish B12 levels.

Signs and Symptoms

What was most interesting to me after reading this case study was a quote in the article stating that paresthesias and ataxia were the most common initial symptoms in patients with B12 deficiency. This is in start contrast to what I was taught in school: that is, neurologic symptoms are a late manifestation of deficiency and are preceded by such complaints as glossitis (burning of the tongue), along with weakness, weight loss, back pain, diarrhea, and constipation.

Clinical Pearl In this case, after a 14-month ordeal, the woman was successfully treated with vitamin B12. The article went on to state: "Neuropathy related to vitamin B12 deficiency is not rare." Clinicians who have patients with upper or lower extremity paresthesias of unknown etiology unresponsive to conservative care with normal or equivocal diagnostic testing may want to investigate the possibility of a frank or subclinical vitamin B12 deficiency.

Quick B12 Facts 

• discovered in 1948 as an isolated red pigment from liver concentrate;
  
  
• largest and most complex of all vitamin molecules;
  
  
• only vitamin that requires a specific substance (intrinsic factor) for absorption;
  
  
• best food sources: organ meats, muscle meats, poultry, dairy, and fish;
  
  
• RDA: 3 mcg per day;
  
  
• adult liver stores 2,000-5,000 mcg;
  
  
• main functions: red blood cell formation; carbohydrate, protein, and fat metabolism; nerve tissue maintenance;
  
  
• 30 percent of vitamin B12 is lost during ordinary cooking; vitamin B12 is also destroyed by light;
  
  
• Vitamin B12 in supplements is produced from bacteria and fungus cultures grown in special media;

Signs and Symptoms

Intrinsic Factor Deficiency

B12 Deficiency 

• tongue pain
• muscle weakness
• weight loss
• back pain
• paresthesias
• anemia is rare
• (Pernicious Anemia) 
• anorexia
• shortness of breath
• burning of the tongue
• abdominal pain
• neurological disturbances
• depression

Common Causes of Deficiencies 

• strict vegan diet
• infants breast-fed by vegan mothers
• lack of intrinsic factor
• intestinal disorders such as celiac disease or sprue
• parasites and tapeworm
• hyperthyroidism

Toxicity 

• There are no known toxic effects of vitamin B12.
• Folic acid supplements to a patient with a vitamin B12 deficiency can lead to serious neurological damage and is contraindicated.

References

Ensminger, Konlande, and Robson. Foods and Nutrition Encyclopedia, 1st ed. Pegus Press, Clovis, California, 1983.

G. Douglas Andersen, DC, DACBSP, CCN
Brea, California