Vitamin B12 is the most chemically complex of any vitamin. It is only made by bacteria, including those in your intestines. You do need other sources as well. The Merck Manual lists the best food sources as liver and other organ meats, beef, pork, eggs, milk and milk products. In order to utilize the vitamin B12 in foods, you must have the intrinsic factor available in your stomach. This factor combines with the B12 in the small intestine, where the vitamin is actually absorbed. As people age, they tend to produce less of the intrinsic factor, and this is one cause of deficiency signs. An autoimmune disorder called pernicious anemia is another. A diet too low in vitamin B12 can result in a deficiency. Any condition that affects your stomach, small intestine or pancreas can cause deficiency by interfering with the chemical reactions needed to process B12.
Digestive System
One of the early signs of B12 deficiency might be a burning sensation in the tongue or a tongue that appears red and beefy. Loss of appetite and weight can occur as well as intermittent constipation and diarrhea. There may be pain in the stomach from an inflammation called gastritis. The spleen and liver may become enlarged.
Nervous System
These signs can occur either before or after anemia develops. If B12 deficiency is not treated, the neurological problems can be severe. Numbness in your feet with a tingling sensation may be one of the earlier signs. Loss of sensation in your feet can also occur. Some people lose the ability to sense where one part of the body is located in relation to the rest of the body. These changes in the nervous system can cause gait disturbances and mental and emotional symptoms.
Anemia
According to "Wintrobe's Clinical Hematology," the anemia caused by B12 deficiency may be discovered before any other sign or later in the progression of the condition. This is a specific type of anemia called megaloblastic anemia. As with other types of anemia, you may notice pale skin, shortness of breath and fatigue. There are tests that can determine whether anemia is from vitamin deficiency or other causes.
References
- "The Merck Manual" Seventeenth Edition; Editors Beers, MD and Berkow, MD;1999
- Jane Higdon, Ph.D.; Linus Pauling Institute Oregon State University; 2003; Updated in 2007 by Victoria J. Drake, Ph.D. and reviewed in 2007 by Jeffrey Blumberg, Ph.D., F.A.C.N.; Professor and Associate Director; Jean Mayer USDA Human Nutrition Research Center on Aging; Tufts University
- "Wintrobe's Clinical Hematology"; Editors Greer MD, Foerster MD, FRCPC, Lukens MD, Rodgers MD, PhD, Paraskevas MD, and Glader MD, PhD; 2004
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