A child is exclusively fed on cow’s milk, the deficiency seen in:
**Core Concept**
Cow's milk is a good source of protein and calcium, but it lacks vitamin B12, which is essential for the production of red blood cells and the maintenance of the nervous system. Vitamin B12 deficiency can lead to various health problems, including anemia and neurological disorders.
**Why the Correct Answer is Right**
Vitamin B12 is obtained from animal products, and cow's milk is not a significant source of this vitamin. If a child is exclusively fed on cow's milk, they may develop a deficiency of vitamin B12, which can lead to megaloblastic anemia. This type of anemia is characterized by the production of abnormally large red blood cells that are not able to function properly.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the scenario, as it does not address the nutritional content of cow's milk.
**Option B:** This option is incorrect because cow's milk is not a significant source of vitamin D, which is important for bone health and immune function.
**Option C:** This option is incorrect because cow's milk is not a significant source of iron, which is essential for the production of red blood cells.
**Clinical Pearl / High-Yield Fact**
It's essential to note that vitamin B12 deficiency can be prevented by consuming animal products, such as meat, fish, and poultry, or by taking supplements. If left untreated, vitamin B12 deficiency can lead to serious complications, including neurological damage and increased risk of infections.
**Correct Answer:** D. Vitamin B12 deficiency.