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On February 12, 2010, in MEDICAL FACTS, Vitamins, by Dr. Tuchinsky

A common cause of fatigue.

Vitamin B-12 (also known as cobalamin) deficiency is one of the most overlooked causes of fatigue. The problem lies in the fact that our understanding of proper levels of this vitamin is still emerging. For example, most American laboratories draw cut off point for normal level at 200 ng/ml.

The definition is vague.

In Japan the recent guidelines dictate that any level below 550 ng/ml requires supplementation because people with levels below that do not function at the optimal level (and this would represent almost one third of the U.S. population!). American medicine has made a step forward in the recent years and now recommends further assessment of those with borderline levels of 200-400 with additional, more expensive tests with complicated names: methylmalonic acid and homocysteine. These substances are toxic substrates of metabolic reactions that cobalamin is involved in, and elevated levels signify cobalamin (B-12) deficiency

Aggravating factors.

Due to the fact that a very large supply of B-12 has been generated early in our life and stored in liver for later use, the symptoms of deficiency may not present till much later in life, when the stores become depleted. In women this can often be precipitated by pregnancy and breastfeeding. However, the symptoms are very non-specific and develop very slowly and gradually, and therefore the problem is often never recognized if it remains mild or discovered only once it has advanced to being severe.

How does Vitamin B-12 deficiency present?

However, mild B-12 deficiency is much more prevalent than previously thought. While severe deficiency leads to a myriad of problems, including neurologic deficits and memory loss, the mild one may only present itself with fatigue and “brain fog”. The deficiency is often due not to poor diet but to impaired absorption of this vitamin by the stomach cells, called intrinsic cells. These cells, just like pancreatic cells in diabetes, can be attacked and destroyed by one’s own immune system. This condition is called pernicious anemia, but the name is misleading since one may experience fatigue and other symptoms long before anemia will develop.

Treatment for B-12 deficiency.

The treatment for vitamin B12 deficiency is very simple. Although injections used to be the standard of care for a long time, it has recently been established that most people, especially those with mild form of deficiency, do well by taking oral supplements in high enough dose (>1000 mg). Those can be purchased over the counter in any pharmacy or vitamin store. Try to find the one that says “methylcobalamin” and not cyanocobalamin, it appears to be better absorbed through the stomach. Once treatment is started, most people notice significant improvement within a couple weeks.




Image: Salvatore Vuono /

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  1. Geraldo Roseboro says:

    Vitamin B12 was discovered from its relationship to the disease pernicious anemia, which is an autoimmune disease in which parietal cells of the stomach responsible for secreting intrinsic factor are destroyed. Intrinsic factor is crucial for the normal absorption of B12, so a lack of intrinsic factor, as seen in pernicious anemia, causes a vitamin B12 deficiency. Many other subtler kinds of vitamin B12 deficiency and their biochemical effects have since been elucidated.;*-^

    Most up to date short article straight from our very own online site

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