MELAKA, July 13 -- A black stool can mean nothing at all, or it can be the body's first warning sign of life-threatening internal bleeding from the upper gastrointestinal (GI) tract.

The difference, according to Dr Quek Yeow Ling, Consultant General Surgeon at Oriental Melaka Straits Medical Centre, comes down to colour, texture, smell and what else is happening to the body.

"Certain foods such as seaweed, black sesame and blueberries, as well as iron tablets, can make stools look darker. But bleeding is more likely if stools are jet black, sticky and tar like, extremely foul smelling, and accompanied by dizziness, weakness or vomiting blood," he said.

Upper GI bleeding, from the oesophagus, stomach or duodenum, is a medical emergency....