B12 Deficiency & Paresthesia

Vitamin B-12, or cobalamin, is a member of the B complex family. However, B-12 differs from other B vitamins in several respects. Even though it is water soluble like other B complex vitamins, it is stored in your liver for many months or even years. B-12 is the only vitamin that contains an essential mineral, namely cobalt. Food-based B-12 requires the presence of a gastric carrier protein called intrinsic factor for optimal absorption from your intestine. Vitamin B-12 deficiencies usually occur as the result of inadequate absorption, but poor dietary intake can cause deficiency in specific groups of people.

Sources

Vitamin B-12 is only found in appreciable amounts in animal protein foods. Nutritionist Elson Haas, M.D., reports that organ meats, such as heart, liver and kidney are particularly good sources. Red meats, fish, shellfish and egg yolks are also high in vitamin B-12. Milk products and fermented soy, such as miso and tempeh, contain some B-12. According to Haas, strict vegans can develop B-12 deficiency if they do not take supplements.

Functions

Vitamin B-12 serves a limited number of functions in your body, but those activities are crucial for your survival and health. The Linus Pauling Institute at Oregon State University states that vitamin B-12 serves as a cofactor for two enzymes which play vital roles in fat and protein metabolism, hemoglobin and red blood cell production, DNA and RNA maintenance and myelin synthesis and repair. Myelin is the lipid-rich insulation that surrounds and protects your nerve cells.

Deficiency and Paresthesias

Vitamin B-12 deficiency leads to anemia and nerve damage. A June 2002 case report in "International Journal of Clinical Practice" reports that paresthesias -- numbness, tingling or other unusual sensations -- are common among B-12-deficient persons. "The Merck Manual of Diagnosis and Therapy" states that B-12 deficiency causes peripheral neuropathy and injury to the white matter of your brain and spinal cord, which manifests as confusion, impaired mental function, weakness, difficulties with balance and walking, delirium, paranoia and paresthesias. If vitamin B-12 deficiency is not treated, the nerve damage can become permanent.

Considerations

Vitamin B-12 deficiency develops insidiously, due to your body's capacity to store this nutrient for long periods of time. Paresthesias associated with B-12 deficiency indicate ongoing nerve damage resulting from a chronic problem with B-12 absorption. Treatment for such a deficiency might require frequent injections of vitamin B-12 for several weeks, followed by lifelong supplementation with oral or sublingual B-12. Daily B-12 requirements for adults vary from 2.4 to 2.8 mcg, depending on pregnancy status, but daily doses of 500 to 1,000 mcg are well-tolerated. If you have paresthesias associated with vitamin B-12 deficiency, consult your doctor.