Vitamin B12 Importance, Deficiency, &Surprisingly Limited Sources

Here’s a rather timely article – bearing in mind all the media interest in B vitamins….

Sep 8, 2010 Amanda Hardison

Vitamin B12 Supplements - Wikimedia Commons-Ragesoss

Vitamin B12 Supplements – Wikimedia Commons-Ragesoss
Most people don’t realize vitamin B12 is only found in meat, dairy and eggs. Without B12, there can be a range of physiological problems.

Vitamin B12 is an essential vitamin that is required for several basic and vital processes in the body, notably the formation of red blood cells and of myelin sheaths (the insulation of nerve cells in the brain). Vitamin B12 is one of the 8 B vitamins essential for human health. It is the biggest of all vitamins, not just of the B vitamins, and the most complex in structure.

Sources of vitamin B12 are limited to animal products

Vitamin B12 is ONLY naturally found in animal products—meat, fish, eggs, dairy. There has been some research to suggest that eggs inhibit the absorption of vitamin B12, however. Therefore, it is very important for vegans and some vegetarians (depending on how much dairy is consumed) to seek other sources of vitamin B12 such as supplements and fortified foods.

Interestingly, B12 is only manufactured by bacteria, which find their way into many animals. This is why humans can only obtain vitamin B12 from animal products. It is true that these same species of bacteria that produce B12 live inside humans, as well, but they inhabit an area of the gastrointestinal tract that is so far down that they are not absorbed by the human body before being excreted. Therefore, humans must get B12 from outside the body. Animal products are the only natural way to consume B12. However, many breakfast cereals, soy milks, energy bars, vitamin drinks, etc., are fortified with vitamin B12 to allow for people who don’t consume much or any animal product to obtain vitamin B12 from food. Supplements can also be taken in order to maintain proper B12 levels in the body.

Vitamin B12 is essential for several vital processes in the body

Red blood cell formation—vitamin B12 is required for DNA production, which is needed in rapidly dividing cells. Red blood cells are constantly dividing into new cells in the bone marrow; without DNA production, this cannot occur.

Neurological/nervous system health—vitamin B12 is required for the synthesis of fatty acids. Without these fatty acids, which make up lipids (fats), myelin cannot form. Myelin forms a sheath around neurons; this sheath acts much like the rubber part of an electrical wire, insulating the nerve cells as signals are conducted through them.

What happens to if these vitamin B12-guided processes cannot occur?

If red blood cell formation is affected by not having newly made DNA, the cells just become larger instead of dividing. This results in very low numbers of abnormally large red blood cells, a type of anemia.

If myelin cannot be created, signals cannot transport efficiently through the neurons. Symptoms of this include depression, irritability, dementia, and permanent nerve damage, among others.

Full list of vitamin B12 deficiency symptoms

Some symptoms include: fatigue, irritability, depression, forgetfulness, a brain fog, sleep disturbances, numbness/tingling in extremities, coordination problems, mania, psychosis, depression, personality changes, red and sore tongue, sores at the corners of the mouth, migraines.

Who should get tested for vitamin B12 deficiency?

Everybody. A 2001 study showed B12 deficiency in the U.S. to be 39%. Determining what level of B12 constitutes too low for clinical health is still under debate, so the actual percentage of people with B12 deficiency is still unclear. However, since this result was published, there have been other estimates of vitamin B12 deficiency that put the numbers not far off from this statistic. Vegetarians who don’t consume many dairy or egg products, in addition to vegans especially need to check their vitamin B12 levels. These individuals must either consume fortified food products containing vitamin B12 or take supplements in order to get the B12 needed for proper health. However, it is ideal to get tested for vitamin B12 levels in the body, regardless of diet as vitamin B12 deficiency is not uncommon. A simple blood test can be ordered by one’s doctor in order to test B12 levels. If low, more tests can be done to determine the cause of the deficiency.

What causes vitamin B12 deficiency?

Other than not consuming much B12 in one’s diet, B12 deficiency can result from an inability to absorb it. Several things can cause this malfunction.

Pernicious anemia is a disorder where the immune system attacks the digestive tract, which inhibits the absorption of vitamin B12, and hence leads to the symptoms of pernicious anemia described in the name of this disease: low amounts of red blood cells. This occurs because a protein called intrinsic factor can no longer be produced once a specific part of the small intestine is destroyed by autoimmune disease. Intrinsic factor is necessary for B12 uptake by the body.

Elderly often lose the ability to produce intrinsic factor, leading to vitamin B12 deficiency, which is quite common in older individuals. In addition, any diseases or surgical procedures that affect this part of the small intestine that produces intrinsic factor can lead to vitamin B12 deficiency. These include Crohn’s disease, celiac disease, parasites, and bacterial overgrowth. Chronic alcohol abuse, cigarette smoking, and carbohydrate overload can all block the absorption of vitamin B12, as well.

Interesting research on vitamin B12

There are several other interesting facts about vitamin B12 that indicate the need for much more research on this fascinating vitamin. For example, B12 is currently be explored as a potential treatment for cyanide poisoning as it binds strongly to cyanide.

Another area of research on B12 is its potential correlation to cardiovascular disease. Homocysteine, an amino acid, is often correlated with the presence of cardiovascular disease; vitamin B12 breaks down homocysteine, removing it from the blood. However, the removal of homocysteine from the blood doesn’t reverse disease, suggesting it may merely be a by-product of another risk factor for heart disease.

Vitamin B12 has been linked to the presence of canker sores.

It is also being studied in regards to Alzheimer’s disease as the symptoms of vitamin B12 deficiency are very similar to that of Alzheimer’s disease. If this proves to be true, it is possible some diagnosed Alzheimer’s patients could be treated and/or cured with the treatment of B12 as they would have been misdiagnosed when really they have B12 deficiency.

A final exciting field of research with vitamin B12 is its potential use as a drug delivery vehicle for cancer cells as vitamin B12 is crucial, and therefore utilized, in rapidly dividing cells. Cancer is defined by rapidly dividing cells gone wrong, so B12 is certainly incorporated into this environment. If cytotoxic drugs could be coupled to B12, then a potential new targeting mechanism for cancer treatment could be developed.

In short

Vitamin B12 is very important to human health. However, many don’t realize they are deficient as the natural sources of B12 aren’t always included in everyone’s diet. Also, many people simply cannot absorb it. Therefore, making sure fortified foods are included in any diet low in B12 and getting blood B12 levels tested are very important steps to take to maintaining good overall health.


Wikipedia, “Vitamin B12 Deficiency” *

Wikipedia, “Vitamin B12

Andres E, et. al., “Efficacy of Oral Cobalamin (Vitamin B12) Therapy

Ebbing M, et. al., “Combined Analyses and Extended Follow-up of Two Randomized Controlled Homocysteine-Lowering B-vitamin Trials

Chan A, et. al., “Cobinamide is Superior to Other Treatments in a Mouse Model of Cyanide Poisoning

Ruiz-Sanchez P, et. al., “Vitamin B(12) as a Carrier for Targeted Platinum Delivery: In Vitro Cytotoxicity and Mechanistic Studies

Wikipedia, “Intrinsic Factor

Michigan State Univeristy, “Lipids

USDA, “B12 Deficiency may be More Widespread than Thought

Frankel EP, et. al., “The Effect of Vitamin B12 Deprivation on the Enzymes of Fatty Acid Synthesis

*All articles accessed on September 8, 2010.

Copyright Amanda Hardison. Contact the author to obtain permission for republication.