Vitamins are substances that the human body requires but is unable to synthesize and therefore, must obtain externally. Deficiencies in three B vitamins, B1 or thiamine, B3 or niacin and B12 or cobalamin are known to cause neurological disorders. Thiamine deficiencies result in a disease called beriberi, which causes peripheral neurological dysfunction and cerebral neuropathy. Niacin deficiencies cause a wasting disease known as pellagra, which affects the skin, mucous membranes, gastrointestinal tract as well as the brain, spinal cord and peripheral nerves. Cobalamin deficiencies most often result in the disease pernicious anemia. Neurological symptoms of pernicious anemia include numbness in the extremities, impaired coordination and a ringing in the ears.
Thiamine was the first water-soluble vitamin to be discovered, and is therefore, also known as vitamin B1. Thiamine deficiency, or beriberi, manifests itself as both wet beriberi, which affects the cardiovascular system, and dry beriberi, which causes neurological dysfunction. People suffering from beriberi exhibit muscle atrophy or wasting (especially in the legs), edema (swelling), mental confusion, intestinal discomfort and an enlarged heart. Severe cases of dry beriberi may result in Wernicke-Korsakoff syndrome and acute cases of wet beriberi may cause shoshin beriberi. Both of these extreme forms of the disease are sometimes fatal. In most cases, administering thiamine successfully reverses symptoms associated with thiamine deficiencies.
Vitamin B12 deficiency
Vitamin B12 deficiency responds well to administration of cobalamin. Because absorption in the small intestine is often part of the problem, the best way to administer cobalamin is by intramuscular injection on a daily basis. After 6 weeks, the injections can be decreased to monthly for the rest of the patient's life. Usually, response to this treatment alleviates all symptoms of the disease. In severe cases, a blood transfusion may be needed and neurological conditions may not be completely reversed.
In most cases, rapid administration of intravenous thiamine will reduce symptoms of thiamine deficiency. Continued dosages of the vitamin should be continued for several weeks accompanied by a nutritious diet. Following recovery, a diet containing one to two times the recommended daily allowance of thiamine (1-1.5 mg per day) should be maintained. Shoshin beriberi requires cardiac support as well. Thiamine has not been found to be toxic for people with normal kidney function, even at high doses.
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NIH/National Digestive Diseases Information Clearinghouse. 2 Information Way, Bethesda, MD 20892-3570. (301) 654-3810 or (800) 891-5389; Fax: (301) 907-8906. email@example.com. <http://www.niddk.nih.gov>.
National Heart, Lung, and Blood Institute (NHLBI). P. O. Box 30105, Bethesda, MD 20824-0105. (301) 592-8573; Fax: (301) 592-8563. NHLBIinfo@rover.nhlbi.nih.gov. <http://www.nhlbi.nih.gov>.
Juli M. Berwald, PhD