Pellagra is a systemic disease which results from severe vitamin B3 (Niacin) deficiency. Mild deficiency may go unnoticed, but a diet chronically low or without Niacin may result in the 4 D's: diarrhea, dermatitis, dementia, and possibly even death. By: content://com.android.chrome.FileProvider/images/screenshot/16346621956511161789231.jpg