Vitamin B12 deficiency can lead to __________.

Vitamin B12, also called cobalamin, is a water-soluble vitamin essential for the production of red blood cells, DNA synthesis, and proper nervous system function. A lack of this vitamin disrupts these processes and can lead to a specific type of anemia called pernicious anemia.

Pernicious anemia occurs when the body is unable to absorb enough Vitamin B12 from the diet. This can be due to:

• 
  

  Intrinsic factor deficiency: A protein produced by the stomach that is necessary for Vitamin B12 absorption.

  
  


• 
  

  Dietary deficiency: Common in strict vegans who do not consume animal products, which are primary sources of Vitamin B12.

  
  


• 
  

  Gastrointestinal disorders: Conditions like Crohn’s disease or celiac disease can reduce absorption.

  
  

The deficiency leads to the production of megaloblasts, which are abnormally large and immature red blood cells. These cells cannot carry oxygen efficiently, causing symptoms such as fatigue, weakness, pale skin, shortness of breath, and neurological issues like numbness or tingling in the hands and feet.

Comparing the options:

• 
  

  Insomnia → may occur occasionally but is not directly caused by Vitamin B12 deficiency.

  
  


• 
  

  Microcytic anemia → refers to small red blood cells, usually caused by iron deficiency, not B12 deficiency.

  
  


• 
  

  Pernicious anemia → correct, characterized by large red blood cells (macrocytic) and neurological symptoms.

  
  


• 
  

  None of these → incorrect.

  
  

Early detection and treatment of Vitamin B12 deficiency with supplements or injections can prevent permanent nerve damage and correct anemia.

Thus, Vitamin B12 deficiency can lead to pernicious anemia (Option C), highlighting the critical role of this vitamin in human health.