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Vitamin B12: Critical Dietary Component

W. Thomas Payne

Vitamin B12 is one of the critical components in a healthy diet. By the time you realize you have a B12 dietary deficiency, serious side effects involving the nervous system, muscles and blood are probably already manifesting themselves. Are you getting enough B12 vitamins in your diet?

What is B12?

Vitamin B12

Vitamin B12 (also called cobalamin because it contains the element cobalt) is a water soluble vitamin. In a crystalline state, it is red in colour. B12 has the chemical formula C61-64 H84-90 N14 O13-14 PCo. Structurally, it looks like a latticework ball surrounding a single atom of cobalt, and is thought to be the sole compound used in our biology that contains such a bond between carbon and a metal.

Who Needs B12?

Humans are incapable of producing B12, the necessary metabolic biochemical pathways do not exist in our species to build B12 from scratch, so the only way to get vitamin B12 is through our diet.

The requirements for an adequate amount of B12 in a healthy person's diet vary by age, body weight, and the dietary requirements for a pregnant or lactating woman are even higher because she is supplying the B12 necessary for the growing child.

A healthy adult needs about 6 micrograms of vitamin B12 every day.

Where Do I Get B12?

Vitamin B12 is found in most meats and animal products such as milk and eggs. Commercial cereal products are also sometimes fortified with Vitamin B12. Dietary supplements are also available in pill and liquid form.

How Does My Body Absorb Vitamin B12?

Vitamin B12 is found bound to the peptides in proteins typically found in the muscle, liver, and kidneys of large animals, and is highly concentrated in mollusks such as clams and oysters.

In your stomach, these proteins are exposed to hydrochloric acid and pepsin (an enzyme that breaks down peptide bonds), breaking the B12 molecules free from those proteins. At the same time, your stomach lining releases a protein called the intrinsic factor, which binds to the B12 and carries it into the small intestine.

An absence or decline in the amount of intrinsic factor or pepsin can lead to a condition called pernicious anemia, which is fatal if not treated.

Vitamin B12 is absorbed through the linings of your small and large intestine, primarily in the ileum, the lower portion of your small intestine. Calcium is required for the proper transport of B12 into the bloodstream. About 1 to 5% of B12 absorption is passively achieved by the reabsorption of water in the large intestine.

Your body stores between 1000 and 5000 micrograms of B12 in your liver and kidneys.

What Does B12 Do?

Vitamin B12 is necessary for proper formation of new red blood cells, the myelin sheath on neurons, some neurotransmitters, and for the proper transcription of DNA. It is a critical component in protein synthesis, bone marrow formation, and in newborn infants, proper brain growth.

In order for B12 to function properly, a person needs adequate supplies of vitamin B6 (niacin), folic acid, and iron. A deficiency in any of those substances can lead to the symptoms of B12 deficiency.

Without proper amounts of B12, your body does not heal properly, because it is a vital component in DNA transcription and protein formation.

What To Look For in B12 Deficiency?

Because of the wide array of functions that rely upon adequate dietary intake of B12, the symptoms of B12 deficiency are many and varied, and they symptoms for deficiency in vitamin B12 often resemble other disorders.

Principal symptoms are anemia, lack of mental acuity, a tingling in the hands and feet, and general lethargy. Because of the complex pathway in which B12 is absorbed into the body, the actual problem causing the B12 deficiency can be difficult to diagnose, and adding B12 to the diet alone may not suffice to get it into the blood stream.

Inadequate supplies of B12 have been linked to cardiovascular disease, due to the role B12 plays in the proper metabolism of cholesterol.

Other conditions that can lead to B12 deficiency include celiac disease (gluten allergy that causes damage to the small intestine), Crohn's disease, and deficiencies in folic acid and iron. Aging also affects the amount of intrinsic factor and pepsin released in the stomach lining, which must be present in adequate amounts for protein to be broken down, and B12 released.

How Do I Get Enough B12?

For a healthy person, adequate supplies of B12 are consumed through meats, dairy products, eggs, and shellfish. No toxic dosage of B12 has been identified, because any amount in excess of the body's requirements are passed out through the kidneys.

If the pathway for B12 has broken down in the intestinal tract, adding crystalline B12 along with coenzymes methylcobalamin and adenosylcobalamin, through passive absorption along the cell lining of the intestinal tract.

In severe cases, intramuscular injections of B12 in crystalline form maybe called for. As with any medical disorder, seek the advice of your medical doctor.


National Institutes of Health, 'Dietary Supplement Fact Sheet: B12'

Vitamin and Herb University 'Vitamin B12: Vital Nutrient for Good Health,' Sally Fallon and Mary G. Enig PhD

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