It’s estimated that up to 40 percent of independent living elderly patients have a vitamin B12 deficiency, and that the number may be as high as 80 percent to 90 percent in nursing homes. Mostly, this is due to gastrointestinal problems, especially gastric atrophy with a loss of intrinsic factor needed for absorption from the stomach. It can also be caused by taking medications that alter the gut’s physiology. Problems can range from subclinical asymptomatic cases to full-blown deficiencies with psychosis involvement.

It is known that doses of vitamin B12 greater than 2,000 mcg do not require intrinsic factor for absorption from the intestines. In addition, the best form is the sublingual form that is absorbed directly into the bloodstream from under the tongue. It requires no intrinsic factor. Blood tests have confirmed this is a best way to take B12.

Most doctors give an injection of a form called cyanocobalamin. This form includes cyanide, the highly poisonous substance, combined with cobamin, the actual molecule. While making the compound more stable, cyanide will also saturate the tissue and can cause some toxicity. Giving babies or children this form is very dangerous, and should never be done.

The best forms are methylcobalamin and adenosylcobalamin. I prefer to use sublingual methylcobalamin.

Most vitamin B12 is stored in the liver for a very long time. Blood levels (serum levels) are unreliable because tissues, especially muscle tissue, may be very deficient even with normal blood levels.

Drugs that increase B12 deficiencies include metformin, antacids, H2 blockers, colchicine, cholestyramine, anticonvulsants, antibiotics, and nitrous oxide. Pregnancy and lactation also induce a deficiency.

A deficiency of vitamin B12 can cause abnormal brain functioning and even brain lesions. It can also lead to DNA defects and high homocysteine, and impair the formation of some brain neurotransmitters. In addition, abnormalities in B12 can lead to folate deficiencies.

Depression is common with vitamin B12 deficiency, as are abnormalities in the formation of myelin — which is seen in MS. The brain and spinal cord are both very dependent on vitamin B12 for its health and function. Severe deficiencies can lead to tingling of the feet and hands (paresthesia), a loss of balance (ataxia), bowel and bladder problems, incontinence, visual problems, and low blood pressure.

Some people present with a psychosis, such as suspiciousness, hallucinations, disorganized thought processes and paranoia. Ironically, these manifestations can occur before abnormalities in the blood (pernicious anemia).

Early treatment is essential.