GREEN STOOLS: MOST RELEVANT CAUSES AND TREATMENTS - MEDICINE - 2026

The green stools tend to be rare in adults and usually interpreted as a sign of alarm. However, although they can sometimes be synonymous with a serious problem, most of the time they are the result of benign and self-limited conditions.

In young babies, especially those who are exclusively breastfed, green or yellow-green stools with a somewhat liquid consistency are usually normal. Babies adopt the consistency and color of adult stools as new foods are introduced from 6 months of age.

In older children or adults, when stools decrease in consistency and turn green, it is necessary to determine whether this change is isolated or associated with other symptoms, such as abdominal pain or nausea.

Depending on the presentation of this change in stool color, it can be determined whether it is an irrelevant event or a serious health risk.

What is the normal color of stool due to?

The normal color of stools (dark brown) is a consequence of the oxidation and degradation of bile pigments throughout the digestive tract.

As it breaks down by digestive enzymes and bacteria, bile turns from bright green to dark yellow, then brown.

This process is slow and progressive, and occurs throughout the entire digestive tract, so that the green bile found in the duodenum - the first portion of the small intestine - ends up being dark brown once it reaches the rectum - the last portion. of the digestive tract - after an average transit of 6 to 8 hours.

When this process is altered in some way, the color of the stool changes, often turning dark green.

Causes of green stools

While the best known cause of green stools is diarrhea, this is not the only cause; in fact, there are different situations in which stool can change its color by turning green without this necessarily implying a problem.

Therefore, the association between green stools and specific symptoms is important. For example, in most cases diarrhea is accompanied by abdominal pain, nausea and a change in color of stools, but when green stools are the product of other causes, other symptoms do not usually appear.

Food can change the color of your stool

What we eat can change the color of the stool, making it dark green.

In this sense, diets rich in foods that contain chlorophyll - such as spinach, chard, and other green leaves - can cause stools to be somewhat less consistent than usual due to fiber, and turn dark green as a consequence. of the chlorophyll contained in the leaves.

On the other hand, the excessive consumption of foods rich in dyes can cause changes in the color of the stool. This is particularly common in children, who are more likely to eat candy with natural or artificial colors.

Vitamin supplements

Some vitamin supplements can change the color of your stools. For example, supplements that contain iron cause stools that are darker than normal, almost black.

Some plant-based supplements, as well as certain vitamins, may cause stools to turn green in some cases.

In neither of these situations should stool color be a concern, as there is no underlying health problem, and stools generally revert to a dark brown color once the pigment responsible for the change in stool is removed. color.

Main conditions that generate green stools

As already mentioned, the color of the stool is largely due to the presence of the breakdown products of the bile along its route through the digestive tract.

For this reason, when bile completes its transit through the large or small intestine faster than normal, it fails to fully degrade and does not reach its final dark brown color. Instead, it remains green or yellow-green, causing the stool to take that color.

In this way, any condition that increases the speed of intestinal transit has the ability to make the stool turn green.

Diarrhea

Both in its acute and chronic forms, diarrhea is associated with an increase in the speed of stool transit through the digestive tract, causing them to have a lower consistency, specifically more liquid because they contain more water.

The increase in traffic speed also produces a color change, due to the presence of bile pigments such as biliverdin, which are green instead of brown.

In general, the change in color of the stool towards the green in cases of diarrhea is associated with abdominal pain, nausea, decreased appetite (hyporexia) and, sometimes, vomiting.

It is a generally reversible situation except in cases of chronic diarrhea. Therefore, the stool will return to its normal color once the diarrhea resolves.

Inflammatory bowel diseases

Inflammatory bowel diseases - such as Crohn's disease, ulcerative colitis, and even irritable bowel syndrome - can be associated with increased speed of intestinal transit, chronic diarrhea and, therefore, a change in stool color. towards green.

As mentioned above, the increase in the speed of intestinal transit is responsible for the change in color of the stool when the complete degradation process does not have time to complete.

Surgeries

A colostomy or ileostomy is a procedure to open the intestine to the outside through the abdominal wall before it reaches the rectum. In those cases in which the patient requires these procedures, the stool will change color depending on the segment of intestine that was exteriorized.

In patients with an ileostomy (last portion of the small intestine) or an ascending colon colostomy (first portion of the large intestine), the stool will be more liquid and greenish in color.

On the other hand, when the segment where the colostomy is constructed is the descending colon or the sigmoid (last portion of the large intestine), the stool will tend to be more consistent and dark brown in color.

If it is a definitive colostomy, the body progressively slows down the transit speed to allow a more physiological digestive process, something that can be induced with certain medications. Eventually the stool will take on a darker color.

In cases where the colostomy is temporary, the situation is reversed once normal intestinal transit is restored, after bowel transit replacement surgery.

Treatment

Green stools do not require specific treatment. Instead one must seek to control the underlying cause.

Generated by food

In cases of green stools due to dyes, food or vitamin supplements, it is not necessary to take any special measures, since it is a normal process. If you want to avoid greenish stools, just remove the person responsible.

Generated by acute diarrhea

When green stools are due to acute diarrhea, it is only necessary to wait for it to resolve. It is a self-limited problem that resolves spontaneously within 3 to 5 days.

In the meantime, the patient can be treated with supportive measures, such as oral rehydration and antispasmodics.

Generated by chronic diarrhea

In the cases of inflammatory diseases and chronic diarrhea things get a bit complicated since the underlying disease must be treated; in cases like Crohn's disease or ulcerative colitis it is not an easy task.

However, once the base condition is stabilized, the color of the stool returns to normal.

References

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