Stool Color Changes: Causes from Diet to Disease

Stool color varies due to:

1. Bilirubin (brown pigment); reduced excretion → pale/clay stools (liver/jaundice).
2. Diet: Red meat darkens; greens → greenish/yellow.
3. Gut microbiome: Bacterial enzymes alter pigments; antibiotics change flora → color shifts.
4. Medications: Iron → black; antibiotics → green.
5. Pathology: Blood → red/black/tarry (GI bleed, IBD, colitis).

Persistent/unexplained changes, especially with other symptoms, need medical evaluation.