Originally published in The Ottawa Citizen April 13, 2004
Original Title: Vitamin B12 deficiency
A change in your diet may not be enough to boost vitamin levels
In medicine, there is an old adage that the most common medical complaints are caused by the most common medical problems. Many of my patients have complained about fatigue. This nebulous creature is one of the most common problems faced by family doctors.
The usual suspects are low iron states, anemia, low thyroid hormone, diabetes, depression, infections, poor nutrition or diet and sleep disorders. Granted there are a myriad of other conditions that can cause this problem. However, more than 90 per cent of the time, the old adage rings true; the diagnosis will be one of the above.
Blood tests for the above disorders would follow after a medical history and physical exam.
Interestingly, I have seen a run of vitamin B12 deficiency lately in men and women of all age groups. The chief complaints are fatigue, lack of energy and motivation to complete tasks, vertigo, depression and confusion.
Vitamin B12 (cyanocobalamin) is required to produce red blood cells and maintain proper nervous system function.
B12 is found only in meat and dairy products. Even with the recommended intake of six to nine micrograms per day, several processes within the digestive system must be working in order for proper B12 absorption to occur.
Stomach acid will free B12 that is attached to the proteins in food. This liberated B12 will bind to intrinsic factor, a carrier molecule secreted by specific stomach cells. This B12-intrinsic factor complex will bind only in one region of the small intestine: the terminal ileum or far end of the small intestine. The pancreas will also secrete an enzyme that prevents B12 from binding to other protein complexes.
Let’s look at some of the mechanisms that will disrupt B12 absorption and, with time, lead to a deficiency state.
Long-term use of acid suppressing medication used to treat stomach ulcers, reflux disease and increased acid states (Zantac, Pepcid, Axid, Losec, Pariat, Prevacid, Pantaloc and Nexium) will reduce the amount of free B12 available to bind with intrinsic factor.
About 10 to 30 per cent of Type 2 diabetics using metformin will have problems absorbing B12. Calcium supplements will reverse this medication effect.
Some people’s immune systems can attack and destroy the stomach cells that produce intrinsic factor or the B12-intrinsic factor binding sites in the terminal ileum. This condition is called pernicious anemia. These people lose the ability to absorb B12 at the terminal ileum for life.
Stomach and bowel surgery, severe pancreatic disease and inflammatory bowel diseases such as Crohn’s or ulcerative colitis can impair absorption of B12.
Inadequate dietary B12 intake is commonly seen in vegetarians who avoid all animal and dairy products. Pregnant and lactating women require increased amounts of B12. If they follow a moderate vegetarian diet, they and their infants may become B12 deficient. The vitamin B12 levels in a fetus are twice as high as maternal blood levels.
The clinical complications of vitamin B12 deficiency will vary. Many people will develop macrocytic (large red blood cell) anemia.
When the nervous system is initially affected, people will report a loss of the ability to feel vibrations on their skin or their ability to sense their body position. In the latter condition, they can trip or lose their balance. The condition can progress to spastic or seizure-like attacks, paralysis and fecal and urinary incontinence.
Other nervous system impairments include memory loss, dementia and irritability.
Vitamin B12 is needed to assist in the breakdown of the amino acid homocysteine. Elevated levels of homocysteine are a risk factor for coronary artery disease and blood clots.
The treatment used to be centred on the assumption that people with malabsorption conditions like pernicious anemia required monthly injections of B12. Indeed, there is evidence that shows daily high dose oral replacement of 1,000 to 2,000 micrograms is as good as injection. There seems to be another intestinal area that absorbs B12 if the dose is great enough.
The choice of injection versus oral therapy will depend upon the underlying condition and should be discussed with your doctor
© Dr. Barry Dworkin 2004