A nutritional condition produced by a deficiency of VITAMIN B 12 in the diet, characterized by megaloblastic anemia. Since vitamin B 12 is not present in plants, humans have obtained their supply from animal products, from multivitamin supplements in the form of pills, and as additives to food preparations. A wide variety of neuropsychiatric abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis. (From Cecil Textbook of Medicine, 19th ed, p848)

Descriptor ID	D014806
MeSH Number(s)	C18.654.521.500.133.699.923
Concept/Terms	Vitamin B 12 Deficiency Vitamin B 12 Deficiency Vitamin B12 Deficiency Deficiency, Vitamin B12 Deficiencies, Vitamin B12 Vitamin B12 Deficiencies Deficiency, Vitamin B 12

Below are MeSH descriptors whose meaning is more general than "Vitamin B 12 Deficiency".

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Below are MeSH descriptors whose meaning is more specific than "Vitamin B 12 Deficiency".