Eating nori can cause black stools.

Black stool after eating nori may be caused by physiological factors, or it could result from pathological conditions such as chronic gastritis or gastric ulcers. Symptoms can be relieved through general management or medication. The details are as follows:

I. Physiological Factors

Since nori has a relatively dark color, black stools after consuming nori may occur when food pigments in nori are not fully digested and absorbed by the intestines and are excreted together with fecal matter. This is usually a normal physiological phenomenon that does not require special treatment. The condition of black stool typically resolves on its own after stopping nori consumption.

II. Pathological Factors

1. Chronic Gastritis

If gastric mucosal damage is severe, it may lead to erosive hemorrhagic gastritis, which can cause black stools during defecation—usually unrelated to eating nori. Under medical guidance, patients may take medications such as bismuth potassium citrate capsules, compound aluminum hydroxide tablets, or ilaprazole enteric-coated tablets for treatment.

2. Gastric Ulcer

When a gastric ulcer bleeds significantly, ferric ions (Fe³⁺) in the blood may be converted into ferrous ions (Fe²⁺) by gastric acid and pepsin in the gastrointestinal tract, potentially leading to black stools after eating nori. Patients should follow medical advice and use medications such as omeprazole magnesium enteric-coated tablets, aluminum phosphate gel, or isosorbide malate tablets as prescribed.

In addition, black stools may also be caused by other conditions such as duodenal ulcer, gastric bleeding, or intestinal ulcer bleeding. It is recommended to seek medical attention promptly, identify the underlying cause, and receive treatment as directed by a physician.