Deficiency of which of the following Vitamins causes pernicious anaemia ?

Question

Accepted Answer

Pernicious anemia is a type of anemia that occurs when the body cannot produce enough healthy red blood cells due to a deficiency in Vitamin B_{12}. This vitamin is crucial for the production of red blood cells and the maintenance of a healthy nervous system. Here is a detailed explanation supporting why Option 3, Vitamin B_{12}, is the correct answer:

1. **Explanation for Option 3 (Vitamin B_{12}):**
   - Vitamin B_{12} is essential for the proper formation of red blood cells and DNA synthesis. It also plays a critical role in the functioning and development of brain and nerve cells.
   - Pernicious anemia specifically results from the body's inability to absorb Vitamin B_{12} due to a lack of intrinsic factor, a protein produced in the stomach that is necessary for Vitamin B_{12} absorption.
   - Without sufficient Vitamin B_{12}, the body cannot produce enough healthy red blood cells, leading to the symptoms of anemia, such as fatigue, weakness, and neurological issues.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Vitamin K):**
     - Vitamin K is primarily involved in blood clotting and bone metabolism. A deficiency in Vitamin K can lead to bleeding disorders due to impaired clotting, but it does not cause pernicious anemia.
   
   - **Option 2 (Vitamin E):**
     - Vitamin E is an antioxidant that helps protect cells from damage. While it is important for immune function and skin health, a deficiency in Vitamin E does not lead to pernicious anemia. Instead, it might cause neurological problems and muscle weakness.
   
   - **Option 4 (Vitamin B_6):**
     - Vitamin B_6 is important for protein metabolism, cognitive development, and the production of neurotransmitters. A deficiency in Vitamin B_6 can lead to anemia, but it is not the cause of pernicious anemia. Pernicious anemia is specifically linked to a deficiency in Vitamin B_{12}.

In conclusion, the correct answer is Option 3, Vitamin B_{12}, because it is directly related to the development of pernicious anemia due to its critical role in red blood cell production and neurological health. The other options, while important for various bodily functions, do not cause pernicious anemia when deficient.