VITAMIN B12 DEFICIENCY


Meaning of VITAMIN B12 DEFICIENCY in English

a condition in which an organism fails to receive a sufficient quantity of vitamin B 12 (cyanocobalamin), a micronutrient that is essential to human and animal digestion and nutritional absorption and which is known to prevent pernicious anemia (q.v.). Lack of vitamin B12 occasions defective formation of the papillae (small projections) of the tongue, giving an appearance of abnormal smoothness. A deficiency of vitamin B12 often causes defective function of the intestine, resulting in indigestion and sometimes constipation or diarrhea. A very serious effect is degeneration of certain motor and sensory tracts of the spinal cord: if the degeneration continues for some time, treatment with vitamin B12 may not correct it. Initial numbness and tingling of fingers or toes may, without treatment, progress to great instability of gait or virtual paralysis. Because vitamin B12 is found in animal but not vegetable foods, complete vegetarianism may lead to deficiency. Deficiency may also result from competition for vitamin B12 by the broad tapeworm or by intestinal bacteria growing in cul-de-sacs or above partial obstructions in the digestive tract. Additional nutritional deficiencies, such as those of folic acid or iron, are likely to develop in such cases, as in primary intestinal diseases such as chronic celiac disease, tropical sprue, or regional ileitis, all of which affect the absorptive capacity of the small bowel.

Britannica English vocabulary.      Английский словарь Британика.