Question 1

Why do beets turn your stool or urine red?

Accepted Answer

Beets contain betacyanin, a red pigment that about 1 in 7 people cannot fully break down. It passes through the digestive tract intact, causing pink or red discoloration in stool and urine within 4–24 hours. It clears within 24–36 hours of your last serving and is completely harmless.

Question 2

Why do blueberries change stool color?

Accepted Answer

Blueberries contain anthocyanin pigments that the body doesn't fully absorb. Some of the pigment travels through the gut intact and can cause blue, green, or dark-tinged stools. This is normal and clears within 24–48 hours.

Question 3

Why do iron supplements cause black or dark stool?

Accepted Answer

Iron supplements cause dark, sometimes nearly black stools because unabsorbed iron reacts with sulfur compounds in the gut, forming black iron sulfide. This is expected, listed on supplement labels, and persists as long as you take the supplement.

Question 4

Does activated charcoal cause black stool?

Accepted Answer

Yes. Activated charcoal passes through the digestive tract without being absorbed and causes dramatically black stools. This is completely expected and clears after 1–3 bowel movements.

Question 5

Why does Pepto-Bismol turn stool black?

Accepted Answer

Pepto-Bismol contains bismuth subsalicylate, which reacts with trace sulfur in the gut to form bismuth sulfide — a black compound. This is mentioned on the Pepto box and resolves once you stop taking it.