Home » The 3 D’s , Dermatitis, Diarrhea, Dementia are seen in the deficiency of Vitamins MCQs The 3 D’s , Dermatitis, Diarrhea, Dementia are seen in the deficiency of January 26, 2022 32 Views Q. The 3 D’s , Dermatitis, Diarrhea, Dementia are seen in the deficiency of A. Thiamine B. Riboflavin C. Niacin D. Pyridoxine Answer: Niacin