This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Niacin deficiency causes ? 
Select and explain. 
A. Pigmentation, B. Diarrhea, C. Rash, D. Lactic acidosis
B: Diarrhea
Answer: B: Diarrhea 
Explanation: Ans. is 'b' i.e., Diarrhea Deficiency of niacin (and tryptophan) causes pellagra which is characterized by 3 Ds, i.e. dermatitis, diarrhea and dementia. Pellagra is common in people consuming maize and sorghum (jowar) as their staple foods. These two are poor in niacin and tryptophan, and rich in leucin. Excess of leucine inhibits the conversion of tryptophan into niacin.