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Last updated January 1, 2014

Mold Toxin Reduction of Vitamin B12 and Neurological Function

James Schaller MD, from US Mold

Researchers report that they are finding that chronic indoor mold toxin patients commonly have vitamin B12 deficiencies. This is important for many reasons. First, people are rarely exposed to a single mycotoxin, and do not need this extra insult on top of other mycotoxin damage. Second, vitamin B12 is not a trivial nutrient and slowly developing deficiencies could be serious.

One of my concerns is that mold exposed pateints can start to take poor care of themselves or act in unhealthy ways which will add to the effects that are proposed by these researchers and lower B12 by two means resulting in neurological injury.

As a background, vitamin B12 deficiency is also known as pernicious anemia and low vitamin B12 or cobalamin is a factor in many disorders. The absorption of dietary vitamin B12 occurs in the small intestine and requires a secretion from the stomach known as intrinsic factor. If intrinsic factor is deficient, absorption of vitamin B12 is severely diminished. Vitamin B12 deficiency impairs the body's ability to make blood, accelerates blood cell destruction, and damages the nervous system. Pernicious anemia may be an autoimmune disease. The immune system destroys cells in the stomach that secrete intrinsic factor. Many people with PA have both chronic inflammation of the stomach lining, called atrophic gastritis, and antibodies that fight their intrinsic factor-secreting cells.

The term "pernicious anemia" is occasionally used to refer to any anemia caused by vitamin B12 deficiency. Vitamin B12 deficiency can be due to poor absorption of dietary B12 despite normal levels of intrinsic factor. For example, celiac disease and Crohn's disease may cause B12 malabsorption, which can lead to anemia. Other causes of B12 deficiency include gastrointestinal surgery, pancreatic disease, intestinal parasites, and certain drugs. Pregnancy, hyperthyroidism, and advanced stages of cancer may increase the body's requirement for B12, sometimes leading to a deficiency state. Low stomach acid, known as hypochlorhydria, interferes with the absorption of B12 from food but not from supplements. Aging is associated with a decrease in the normal secretion of stomach acid. As a result, some older people with normal levels of intrinsic factor and with no clear cause for malabsorption will become vitamin B12-deficient unless they take at least a few micrograms per day of vitamin B12 from supplements. In my opinion, individuals with routine use of stomach acid blockers should have supplemented B12.

B12 and Fatigue
Individuals from mold induced B12 deficiency or deficiency from other factors, have specific symptoms. Fatigue is often the first symptom of pernicious anemia, but hundreds of serious medical problems have fatigue as a symptom, so merely grabbing a bottle of B12 could delay true treatment for a serious problem. One common way to diagnoses this is by blood tests.

Symptoms of Severe Vitamin B12 Deficiency

  • fatigue
  • burning of the tongue
  • weakness
  • lost appetite
  • intermittent constipation and diarrhea
  • gut pain
  • weight loss
  • menstrual symptoms
  • emotional and psychological symptoms
  • numbness or tingling in hands and feet

Most of these symptoms can occur before the deficiency is severe enough to cause full anemia.

Over the counter supplementation with vitamin B12 may benefit some individuals with mild deficiency.

Prescription drug treatment for some individuals includes lifelong intramuscular vitamin B12 injections. Other drug options also exist.

Vitamin B12 is found in significant amounts only in animal protein foods -- meat and poultry, fish, eggs, and dairy products. Even small amounts of these foods supply sufficient amounts of vitamin B12 to provide enough for healthy people.

Except for vegans -- those who abstain from eggs, dairy, and other animal products -- virtually no one in North America has a diet fully deficient in vitamin B12. Those who avoid animal protein foods can easily take vitamin B12 supplements instead. Strict vegans commonly develop a dietary deficiency of vitamin B12. People who lack intrinsic factor or have a malabsorption condition need to depend on high amounts of vitamin B12 from supplements and not the lower amounts found in food. Similarly, older people with a vitamin B12 deficiency due to a lack of stomach acid, but not a lack of intrinsic factor, cannot depend on food-based vitamin B12.

Tempeh, a fermented soybean product, provides some vitamin B12. However, the B12 content of tempeh is variable and insufficient to meet dietary B12 requirements. Small but inconsistent amounts of B12 also occur in seaweed and spirulina. Because of this variability, most doctors do not recommend vegetable sources of vitamin B12 to replenish deficient stores.

Drinking Alcohol
Routine alcohol use can lead to gastritis and damage the lining of the intestines, both of which can interfere with vitamin B12 absorption. If B12 deficiency is due to alcoholism, abstinence may prevent further impairment of B12 absorption.

Nutritional Supplements
Commonly 3 to 4 mcg/day of vitamin B12 prevents deficiency. If gastrointestinal function is normal, even these small amounts of vitamin B12 from oral supplementation can prevent deficiency in vegans. If a deficiency already exists, most doctors will recommend an initial vitamin B12 injection, then oral amounts ranging from 500 mcg to 1,000 mcg per day until symptoms subside; this is followed by a maintenance level of approximately 10 mcg per day to prevent future deficiencies.

In a person with true pernicious anemia, generally one should start with an injection. After blood tests become normal, oral vitamin at 1,000 to 2,000 mcg (1 to 2 mg) per day usually works. Yet, if a person lacks intrinsic factor, only about 1% of this oral amount (10Ð20 mcg) will be absorbed, but that amount is more than sufficient to prevent future vitamin B12 deficiency. Many physicians are unaware of this well-researched option and thus unnecessarily recommend lifelong B12 injections.

B12 and Mycotoxins
Vitamin B12 is a source of coenzymes that allow enzymes and basic bodily reactions to occur. B12 is involved in many aspects of crucial methionine and in the prevention of chromosome breakage. The researchers are explicit to say that patients with chronic exposures to toxigenic molds commonly manifest vitamin B12 deficiencies. Since B12 is so highly involved in neuron functioning, it is likely that the interruption of the structure and function of vitamin B12, would in turn interfere with the one-carbon metabolism leading to the neurological manifestations.

B12 should be fully tested for in any possible indoor mycotoxin victim.


Anyanwu EC, Morad M, Campbell AW. Metabolism of mycotoxins, intracellular functions of vitamin B12, and neurological manifestations in patients with chronic toxigenic mold exposures. A review. ScientificWorldJournal. 2004:4:736-45.




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