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 deficiency has a number of symptoms, including paresthesias -- nerve damage that causes numbness, tingling or other unusual sensations.
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.
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 synthesis and nerve maintenance and repair.
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 are common among people with B-12-deficiency. “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.
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 micrograms, depending on pregnancy status, but daily doses of 500 to 1,000 micrograms generally don't cause side effects. If you have paresthesias, consult your doctor.
- “Staying Healthy with Nutrition: Vitamin B12 (Cobalamin)”; Elson M. Haas, M.D.; 2006
- Linus Pauling Institute Micronutrient Information Center: Vitamin B12
- “International Journal of Clinical Practice”; Missed Diagnosis of Vitamin B12 Deficiency Presenting with Paraesthetic Symptoms; A.J. Larner; June 2002
- “The Merck Manual of Diagnosis and Therapy, 18th Edition: Vitamin B12”; Mark H. Beers, M.D., Editor-in-Chief; 2006