10/04/2026
🧬 Niacin Deficiency (Pellagra)
Pellagra is a disease caused by deficiency of niacin (vitamin B3) or its precursor tryptophan. It mainly affects the skin, gastrointestinal system, and nervous system.
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⚠️ Classic Triad — “3 D’s”
1. Dermatitis
• Symmetrical, photosensitive rash (sun-exposed areas)
• Thickened, scaly, hyperpigmented skin
• Casal necklace (rash around neck)
• “Glove-and-stocking” distribution on hands/feet
2. Diarrhea
• Inflammation of GI tract
• Abdominal pain, watery stools
3. Dementia
• Confusion, memory loss
• Irritability → depression → severe cognitive decline
👉 If untreated → Death (4th D)
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👅 Oral & Mucosal Changes
• Glossitis → red, swollen “magenta tongue”
• Cheilosis → cracked lips
• Angular stomatitis → fissures at mouth corners
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🔍 Causes
• Poor diet (low protein, maize-based diet without proper processing)
• Chronic alcoholism
• Malabsorption (e.g., Crohn disease)
• Certain conditions:
• Hartnup disease (↓ tryptophan absorption)
• Carcinoid syndrome (tryptophan → serotonin instead of niacin)
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🧪 Pathophysiology (Simple)
Niacin is needed to make NAD & NADP, which are essential for:
• Energy production
• DNA repair
• Cell metabolism
➡️ Deficiency → tissues with high turnover (skin, gut, brain) are most affected.
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💊 Treatment
• Niacin (nicotinamide) supplementation
• High-protein diet (rich in tryptophan)
• Treat underlying cause
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🥗 Prevention
• Eat foods rich in niacin:
• Meat, fish, eggs
• Peanuts, legumes
• Whole grains
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🧠 Quick Memory Tip
👉 “3 D’s of Pellagra”
Dermatitis + Diarrhea + Dementia
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