Our excretions can actually take on a wide variety of colors. When your poop turns black, there could be a few harmless reasons for it, but it could also be due to certain diseases. We tell you which five causes for the pitch-black tar stool come into question.
The color of your stool can tell you a surprising amount about your current health. Often there are only harmless causes, such as the consumption of certain foods, behind the discolouration. However, diseases or damage to health can also change the color of the excrement. If your stool should be very dark or even pitch black, the following causes could be the cause of the phenomenon.
Table of Contents
Tarry stool: causes of black stool
1. Food
A harmless and completely harmless cause of dark stools is the consumption of certain foods. If you eat a large amount of blueberries , beetroot, dark chocolate or red wine, your bowel movements may turn black the next day. This is due to the strong, naturally occurring colorings found in such foods and is nothing to worry about. Red, green, and blue food coloring, which is used in baking, for example, can also trigger dark stools.
However, if you have not eaten any of the foods mentioned, the following causes could be responsible for the phenomenon known as tarry stool or melena .
2. Eisentabletten
Another reason for tarry stools can be the use of iron supplements. Especially with higher doses, the stool can turn black, but this is harmless. So if your stool changes color because you are taking iron tablets for iron deficiency anemia, do not worry and continue to take the tablets as directed by your doctor. However, if additional unpleasant symptoms such as abdominal pain, constipation or other problems in the digestive tract occur, you should contact your doctor and discuss how to proceed.
3. Bleeding in the upper gastrointestinal tract
In addition to these harmless causes, tarry stool can also be due to a serious condition that requires medical treatment. Dark stools, especially pitch-black stool discoloration, can be the direct result of bleeding in the stomach or esophagus . Because when blood comes into contact with stomach acid, the bright red iron molecule hemoglobin, which is responsible for transporting oxygen in the blood, is converted into dark red to black hematin. Hematin in the stool then causes the dark to black discoloration. Bleeding in your upper digestive tract can be caused, for example, by varicose veins in the esophagus, ruptured blood vessels in the stomach, stomach ulcers or tumor diseasesoccurrence. Bleeding in the esophagus can also result from constant irritation, for example when stomach acid rises up into the esophagus. Reflux disease often causes painful heartburn due to an overproduction of stomach acid.
Good to know: Bright red traces in the stool or on the anus, on the other hand, are more of a sign of damage to the anus – for example enlarged hemorrhoids or anal fissures . If bleeding occurs in the intestine or at the anus, the hemoglobin remains in the blood and is not broken down into hematin.
4. Bleeding in the intestines
If, on the other hand, bleeding occurs in the small or large intestine, the blood that can be seen in the stool is rather light red. However, pitch-black tarry stool can still occur under certain circumstances if the intestine is affected. For example, when the intestinal passage is severely slowed down – in the case of constipation or a sluggish intestine, for example caused by being bedridden or immobility. Then certain intestinal bacteria convert the hemoglobin in the blood into hematin – this leads to tarry stool.
Important: If you have black stools that last for several days and are not due to any of the more harmless causes, you should definitely contact your doctor .
5. Colon Cancer
In addition to prostate cancer and breast cancer, colorectal cancer is one of the three most common types of cancer in Germany. The carcinoma usually occurs in the lower section of the large intestine – then there can be bright red traces of blood in the faeces. In about 25 percent of cases, however, colon cancer is located in the uppermost section of the large intestine – which can lead to dark red to blackish stool discoloration. Cancer of the small intestine is rather rare. Other symptoms of colon cancer (colon carcinoma) include bloating with blood or mucus, cramping abdominal pain, alternating constipation and diarrhea, and pencil stool .
What does tar stool look like?
Exactly how tarry stool looks depends, of course, on the particular cause. If black stool is triggered by food and plant pigments, tarry stool does not differ in consistency and texture from healthy stool. Only the color is then noticeably changed and sometimes pitch black.
However, if bleeding in the digestive tract, diseases of the intestine, bleeding stomach ulcers or bleeding in the esophagus are the causes of black stool, the appearance of the excretions can also change. If there is a lot of blood from a bleeding source in the upper digestive tract, i.e. the esophagus and stomach, tarry stool can also be very liquid. If the stool is black and liquid , it is actually strongly reminiscent of tar.
Tarry stool , which occurs due to bleeding in the intestine and a very long intestinal passage, also smells very strong and unpleasant. If there is constipation in the intestine, the food pulp remains in the digestive tract for a particularly long time. If the source of the bleeding is in the intestines, this is where bacteria begin to break down the hemoglobin in the blood into hematin. Basically, the longer the stool remains in the intestine, the stronger the odor.
Tarry stool in the baby
Black stools and particularly dark stools also occur in newborns. Newborn babies often have black stools if they swallowed their mother’s blood during childbirth . In the stomach of the newborn, the already described decomposition of hemoglobin to hematin takes place through the gastric acid. The tarry stool in babies often returns to normal after a few days.
Babies may have black stools if they suck blood from small lacerations in the nipples while breastfeeding. This form of melena also returns to normal on its own.
