One mg. of Niacin is produced by…………………….. mg. of Tryptophan-

**Core Concept**
Niacin, also known as Vitamin B3, is an essential nutrient that plays a crucial role in energy metabolism. It is a precursor to NAD+ and NADP+, which are vital for various cellular processes, including glycolysis, fatty acid oxidation, and DNA repair. Tryptophan, an essential amino acid, can be converted into niacin through a series of enzyme-catalyzed reactions.

**Why the Correct Answer is Right**
The conversion of tryptophan to niacin occurs through the kynurenine pathway, which involves multiple enzymes, including tryptophan 2,3-dioxygenase and kynureninase. One mole of tryptophan can produce approximately 60 moles of niacin. This conversion is essential for individuals with limited dietary niacin intake, such as those with pellagra, a disease characterized by dermatitis, diarrhea, dementia, and death.

**Why Each Wrong Option is Incorrect**
* **Option A:** There is no established conversion rate for tryptophan to niacin that matches this value.
* **Option B:** This value is incorrect, as tryptophan is not directly converted to niacin in a 1:1 ratio.
* **Option D:** This value is also incorrect, as it does not accurately reflect the conversion rate of tryptophan to niacin.

**Clinical Pearl / High-Yield Fact**
The niacin deficiency disorder pellagra is often referred to as the "four D's": dermatitis, diarrhea, dementia, and death. This mnemonic can help students remember the characteristic symptoms of this disease.

**Correct Answer: C. 60**