Diarrhea after eating is initially a very unspecific symptom that can indicate various diseases. Often spoiled food or food intolerances are the trigger of the symptoms. However, the diarrhea can also begin by chance after eating, without there having to be a connection between the food and the diarrhea. In order to find out these differences, the course of the diarrhoea disease is of particular importance, as it can provide information about the origin of the complaints.
Causes of diarrhea after eating
The causes of diarrhea after eating are many and varied. However, they can be divided into different categories. On the one hand, there are the infectious causes, where the diarrhea is caused by spoiled food.
Bacteria are often found in the spoiled food. If these bacteria cannot be effectively combated in the digestive process of the stomach and intestines, strong abdominal cramps occur shortly after eating, followed by nausea, vomiting and diarrhoea. Other causes of diarrhoea after eating are problems with the digestion of certain food components.
For example, a malfunction of important salivary glands (e.g. the pancreas) as well as other organs that produce digestive enzymes (e.g. the bile) can result in large portions of the ingested food not being digested. In the case of biliary disorders, for example, fatty components cannot be broken down and accumulate in the intestine, which typically leads to fat-shining diarrhea.
Food intolerances are also based on the body’s inability to digest certain food components. Often, however, not all sugar molecules or all proteins are affected, but rather an intolerance of a certain protein or sugar. In the case of lactose intolerance, for example, only lactose cannot be digested; in the case of gluten intolerance, the body cannot digest a certain protein from many types of grain.
As a result, water is infiltrated into the food pulp in the intestine and the intestinal wall becomes inflamed, which can lead to diarrhea, which often occurs immediately after eating the affected food. Do you suffer from diarrhoea after drinking milk? Find out whether lactose intolerance is behind it.
The pancreas is an organ located in the upper abdomen. The pancreas has various functions, but most importantly, it secretes various substances that are important for digesting food in the intestines. These so-called pancreatic enzymes are produced in the pancreas and enter the duodenum through the pancreatic duct.
There they meet the chyme, which has been transported from the mouth through the stomach to the duodenum. The pancreatic enzymes in the duodenum have the task of splitting the proteins and fats from the food so that they can be absorbed into the blood in the following intestinal sections. If the pancreas becomes diseased, this digestive step is no longer fully guaranteed, so the composition of the food pulp in the intestine changes.
This brings the entire digestive system out of balance, so that stool irregularities such as diarrhoea can develop. Bile acids are those substances in the bile that play an important role in the digestion of food fats in particular. Bile is produced in the liver cells, from where it is transported to the gall bladder.
During and shortly after eating – especially if you eat a lot of fatty foods – the gallbladder empties. The bile acids enter the duodenum through the bile duct. There, they mix with the chyme that is already pre-digested in the stomach.
Enzymes from the pancreas are also added to the digestive tract at this point. The bile now has two different functions: it neutralizes the acidic contents of the stomach and at the same time forms small globules in which the fat from the food can collect so that it can be absorbed into the body from the intestine. The bile then passes into other parts of the intestine, where it is responsible for excreting non-water-soluble (and thus fat-binding) products.
In the case of bile diseases, the bile can no longer reach the digestive tract. As a result, the fatty food components are no longer digested well, resulting in so-called acholic bowel movements. These are often yellowish or even greyish and shiny.
However, they can also manifest themselves in the form of diarrhoea.Typically, biliary diseases such as the blockage of the small bile ducts in the liver or the large bile duct outside the liver by gallstones lead to such diarrhea. Food intolerances are very diverse and manifest themselves in very different ways. However, in contrast to the real food allergy, there is no sudden allergic reaction with a burning sensation in the mouth or even swelling of the airways.
Instead, intolerances often first become noticeable in the intestines. Since the mechanisms are triggered by special food components, diarrhea usually occurs after eating. The cause is usually a lack of enzymes, so that certain foods cannot be processed in the intestine.
With lactose intolerance, for example, the milk sugar lactose remains in the intestine because the body cannot break it down into small digestible pieces. The lactose then draws a lot of water into the intestine and can lead to diarrhoea as well as stomach ache. Gluten intolerance, on the other hand, leads to inflammation of the intestinal mucosa, which damages it.
This also leads to a larger accumulation of water in the intestinal tract, which also causes particularly fluid stool and thus diarrhea. Colorectal cancer is a disease that typically only occurs at an advanced age. This causes cancer cells to develop, which grow in the intestinal mucosa.
Over time, their growth causes the lumen (the inner space) of the intestine to become increasingly narrow. If the colorectal cancer lies in relatively high proportions of the intestine, this usually does not cause any changes in the bowel movement, but small tumor bleeding can occur, so that blood deposits or even occult (hidden blood not visible to the naked eye) blood is present in the bowel movement. Do you have blood in your stool?
These could be other possible causes of bloody stool. In the case of colorectal cancer that is located very distally (at the end of the bowel), the relatively hard bowel movement can often no longer easily pass through the narrowed area. This leads to so-called paradoxical diarrhea. The normal bowel movement accumulates from the constriction, this draws more water into the intestine, the liquid stool can pass through the constriction and can make itself felt in the form of diarrhoea.
