Vitamin B12 Information & Benefits

Vitamin B12 is one of eight vitamins in the B complex. A water-soluble vitamin, B12 works closely with other B vitamins, particularly folic acid. Vitamin B12 activates the folic acid coenzyme and is also activated as a coenzyme by folic acid.

Vitamin B12 is necessary for the synthesis of DNA and RNA. It is also involved in the synthesis of red blood cells. In addition, Vitamin B12 protects nerve fibers by maintaining the sheath that surrounds them, and it promotes the normal growth of nerve fibers as well.

In foods, Vitamin B12 is attached to proteins. After the food is consumed, hydrochloric acid and pepsin in the stomach release Vitamin B12 from protein so that it can be absorbed into the bloodstream.

Vitamin B12 deficiency is almost always due to poor absorption rather than inadequate intake. Poor absorption of Vitamin B12 may be due to insufficient hydrochloric acid production in the stomach or to lack of “intrinsic factor,” a substance that binds to Vitamin B12 after it is released from protein and enables it to be absorbed into the blood.

When Vitamin B12 deficiency is due to lack of intrinsic factor, it is called pernicious anemia and is characterized by large, malformed red blood cells.

Because Vitamin B12 is involved in the conversion of folic acid into its active form, folic acid deficiency anemia is another possible consequence of inadequate absorption of Vitamin B12.

Symptoms of Vitamin B12 deficiency include neurological problems that may eventually lead to paralysis of the nerves and muscles. Other neurological symptoms include dementia that may appear to be Alzheimer’s disease. Supplementation with Vitamin B12 may reverse these symptoms. Vitamin B12 deficiency may also be connected with a range of other adverse conditions, including depression, asthma, diabetic neuropathy, and tinnitis (ringing in the ears).

The body needs about two micrograms of Vitamin B12 per day, but because it is not absorbed easily, the actual amount that must be consumed is larger. The best food sources of Vitamin B12 are animal proteins, including meat, fish, poultry, milk, cheese, and eggs. Because Vitamin B12 is obtained primarily from animal products, strict vegetarians (vegans) are at risk for Vitamin B12 deficiency.

Also older people may be at risk for deficiency because they produce less of the intrinsic factor needed to absorb Vitamin B12 into the bloodstream. When there is a concern that diet does not supply adequate amounts of Vitamin B12, supplements may be taken.

Most supplements contain cyanocobalamin, a form of Vitamin B12 that must be converted to methylcobalamin or adenosycobolamin before the body can utilize it. Because of this, only about 2 micrograms of Vitamin B12 may be absorbed from a 100-microgram tablet.

Sublingual supplements of methylcobalamin that dissolve under the tongue are considered the most absorbable type of Vitamin B12 supplement. Sublingual supplements are usually taken in 1000 microgram doses, which are sufficient to maintain daily requirements of B12.

Vegetarians and older people may need larger doses. Since Vitamin B12 is water-soluble, excess amounts are excreted in the urine and little potential for toxicity exists.

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