The color of stool: what should it be?

Have you ever wondered what the healthy color of human feces should be?

You may not know, the consistency and color of our stool can give us valuable information about our health as well as the state of our intestines.

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And sometimes even alert us to some diseases.

If you want to find out how human stools are formed and what consistency and color they should be to be 'healthy', keep reading this page, written for you by Dr. Luisella Troyer, Proctologist Surgeon.

Why DOES WE HAVE to feed ourselves?

Homo Sapiens, like all other mammals and animals in general, is a heterotrophic living organism.

In biology, heterotrophic organisms are defined as all those living things that are incapable of producing the biological nutrients essential to their subsistence from inorganic chemical elements, such as dissolved minerals in water or photonic energy coming from the sun.

All heterotrophic organisms, as opposed to those that are instead autotrophic (such as plants), therefore need to take the necessary energy and chemical compounds required for their subsistence from other life forms, which in turn have either synthesized them themselves or obtained them from other life forms still.

This is why we animals are unable to feed ourselves on raw minerals or energy from the sun alone, but must necessarily provide the necessary nourishment through periodic ingestion of food.

Human beings need, for their survival, a varied and balanced diet, including a little bit of everything: water, carbohydrates (the sugars), proteins, amino acids, and also all those chemical compounds that, although necessary for so many functions of our body, our body cannot produce on its own, and which we have called vitamins.

Like almost all the great apes, the genus Homo, to which we belong, evolved exquisitely omnivorous: our teeth and gastrodigestive system, in fact, are an excellent example of systems evolved precisely to adapt to almost any food, in that now well-known ductility proper to our species.

And from the very beginning of our long gastrodigestive system begins the long journey that allows nourishment to give us the energy we need to live, and thus complete our life cycle.

From food to feces: the long journey of our gastrodigestive system

The intake of nourishment, in the form of food, starts from the mouth.

The human oral cavity is a complex and well-integrated masticatory and phonetic organ, consisting essentially of the tongue, jaw and jaw bones, and two dental arches formed by 32 teeth, divided into 16 elements per palate (upper and lower).

The teeth, especially the molar teeth, grind up food, and the tongue kneads it with saliva, a liquid naturally produced by the salivary glands and consisting mainly of water (99 percent) with some minerals and, most importantly, enzymes.

Human digestion begins precisely with mastication: thanks to the grinding of the molars and mixing with saliva, food becomes a bolus, and is swallowed by swallowing to the pharynx and esophagus, i.e., the first tracts of the gastrodigestive tube.

The bolus is pushed downward not by simple gravity, but by an internal, contracting movement of the esophageal mucosa called peristalsis.

Peristalsis pushes the bolus toward a large pouch located roughly just below the sternum, called the stomach.

There the bolus is broken down and attacked by powerful acidic liquids (stomach acids), which turn it into a kind of thick liquid called chyme.

The chyme, through the duodenal valve, passes into the duodenum, which is the first part of the very long small intestine.

In the small intestine, a very long tube about 7 meters long, chyme nutrients are absorbed by intestinal villi: very thin filaments that dot the entire inner mucosa of the small intestine.

The intestinal villi then send the absorbed nutrients (sugars, amino acids, proteins, etc.) into the bloodstream, where they will then be broken down, refined and reassembled into other molecules by the liver.

At the end of the long small intestine, called the ileum, there is a one-way opening: it is the ileocecal valve, which connects the small intestine with the large intestine, called the colon.

The chyme, which at the end of absorption in the small intestine has now become nutrient-poor but still very fluid-laden, is therefore released into the colon, and is named chyle.

In the colon, a large tube that wraps around the entire abdomen, the chyle is stripped of fluids and electrolytes by lymphatic vessels throughout the intestinal mucosa.

The lymphatic vessels are a fundamental section of the lymphatic system, which is responsible for reabsorbing all the fluids in the chyle, turning the latter into the alvo, that is, the final waste ready to be excreted by defecation.

The transformation of chyme into alvo is helped by a symbiotic mechanism of our gut with certain bacteria that populate and colonize it: this is the gut microbiome.

This microbiome, made up of a large number of our friendly bacteria, attacks the glucose residue in the alvo, ferments it and thus allows it to form soft but compact, easy to be excreted.

The alvus, ready for expulsion, is collected in the rectal ampulla: a natural extasia of the intestine just before the rectum, whose job is precisely to collect fecal material ready for expulsion.

When the ampulla fills sufficiently, we have the signal of going bodily, and defecation can take place.

Through ponsation and the work of the sphincter muscles, the alvus is pushed throughout the rectum to the anal orifice, where it is finally expelled in the process we call defecation.

Thus, feces are the result of this very long journey, which began as early as chewing.

A truly complex pathway, which allows us mammals to appropriate resources produced by so-called 'producer' organisms (essentially, plants), or by consumer organisms (other animals) that, in turn, have fed on other consumers or other producers.

It is the famous circle of life, made possible, for us, by our very digestive system.

Stool formation in the intestine: how does it happen?

As we have seen, the colon is the final organ of our complex gastrodigestive system.

It is a long, thick tube, conventionally divided into five seamless parts: ascending colon, transverse colon, descending colon, sigma and rectum.

The ascending colon is the first sector of the colon, positioned parallel to the sagittal plane of the body: it begins with the cecum and the ileo-cecal valve, which allows the one-way passage of chyme, i.e., food already deprived of nutrients by the villi of the small intestine.

The chyme, a whitish and very liquid substance, is pushed through the entire colon by the movement of peristalsis, and slowly as it travels through the entire organ it is progressively emptied of fluids and electrolytes by the chyliferous vessels located throughout the intestinal mucosa.

The chyme then becomes increasingly solid, but there are still small residues of digestion in it that, for physiological reasons, have not been absorbed by the villi.

These are essentially polysaccharides (sugars) and fiber, that is, material that our body does not eat, and is therefore excreted.

Sugars not assimilated by the villi are harmful to the delicate intestinal mucosa, as well as dangerous because they can raise blood sugar levels in the body.

Fortunately, more than 400 species of bacteria, which make up the so-called 'intestinal bacterial flora' ,live along the entire colon in symbiosis with the mucosa.

These bacteria are our friends as they attack unassimilated sugars and ferment them, producing as waste material acids that are essential for our bodies such as acetic acid, protonic acid and butyric acid.

These acids are extremely important precisely for the mucosa of the intestine, as they protect and nourish it, while also giving it some of the energy it needs to renew its own cells.

Still, in addition to the acids essential to the well-being of the intestinal mucosa, bacterial fermentation in the colon also produces fundamental victims such as vitamin B12 and vitamin K.

The intestinal bacterial flora increases the chyle in volume, keeps it soft, and turns it into alvo, that is, fecal material ready to be excreted.

All the alvus is collected in the very last part of the colon, that is, in the rectal ampulla just above the rectum.

When the ampulla swells sufficiently and thus becomes ready for expulsion, we feel the urge to relieve ourselves (the defecatory urge), and thus activate the voluntary process that, through the action of the external sphincter muscle, allows us to flush the feces out of the rectum and the anal orifice, by defecation.

Gut bacterial flora and its fundamental importance for soft, well-formed stools

The entire interior of the colon is populated, at every moment of our lives, by a very large amount of bacteria, called intestinal bacterial flora.

They are essentially bifidobacteria and lactobacilli, and there are more than 400 species of them.

These microorganisms, as mentioned just above, are indispensable to complete our digestion process, as they live in symbiosis with our intestinal mucosa.

Feeding on undigested polysaccharides (sugars), the fermentation of their metabolism produces fatty acids that are essential to our bodies, some very important vitamins, and, last but not least, protects the intestinal mucosa from malevolent attack by other bacteria or viruses.

This process of perfect symbiosis between us and our friendly bacteria is called eubiosis, and it is a condition that gives well-being and regularity to our gut, which we should all maintain or try to aim for.

The intestinal bacterial flora then provides, not secondarily, for the metabolism and disposal of bilirubin, i.e., a pigment found in (waste) bile that is the result of the breakdown of 'aged' red blood cells and thus replaced by the body.

It is precisely the fermentation of naturally yellow-orange bilirubin by bacteria in the intestines that causes the typical color of formed stool to be brown.

Already knowing this, it's understood how a healthy bacterial flora in perfect symbiosis with the body can exert proper bilirubin fermentation action, resulting in stools that are 'just right' in color (neither too dark nor too light), not particularly foul-smelling, soft and well-formed, with a typical cylindrical shape.

All of this happens precisely because of the presence of gut-friendly bacterial flora-a precious asset that we must always protect and pamper, as it is essential for our gut to function well.

The color of stool: brown yes, but what gradation?

As we initiate seen just above, bacterial fermentation in the gut attacks both the glucose residue in the stool and bilirubin, i.e., the biliary waste from the 'digestion' of red blood cells that are no longer functional, too old or damaged.

Bilirubin is a pigment varying in color between yellow and orange, and when it is attacked by the symbiotic bacteria in our intestines this pigment lingers in the alvo, that is, in the forming stool.

Added to this is also the natural color of fiber, that is, food that is not used by our bodies as nutrition, and is therefore excreted as is.

Depending on the level of quality of bacterial fermentation, given in turn by the level of 'well-being' ,so to speak, of our friendly bacteria, the color of the stool may therefore vary.

Along with color, given that feces is composed of about 70-80% bacteria and fermentation material of the same, depending on the well-being of our colon, their smell will also change.

The analysis of stool color as well as stool smell is an extremely important examination in colonproctology, as it is a primary index of the well-being of our intestines.

In a healthy subject in perfect eubiosis, the emission of feces occurs daily, with the expulsion of soft, well-formed, voluminous fecal material that is brown in color, neither too dark nor too light, and not particularly malodorous.

The color of the brown can change, as mentioned in relation to the quality of the bacterial fermentation and the fiber intake of the diet, but it still should not be too dark or too light.

Major alterations in the shade of brown, either toward black or faded yellow, may indicate major problems in the colon or another part of the body that do not allow food to be properly digested.

Variations to the normal brown of stool may be:

Very dark brown, almost black stool

Stools that are too dark brown in color, tending toward black, may indicate the presence of digested blood, and thus a lesion in the upper colon or in another part of the digestive tract;

Reddish stool

Stools that indicate the presence of food dyes in the stool, or heavy intake of particular foods, such as tomatoes, beets, red fruits, peppers, etc.

Very often this color puts the patient in anxiety and alarm, who thinks he or she has a bad bowel injury, but the symptoms of a colon or rectal injury are quite different (more on this list later);

Greenish stool

Bilirubin is actually a waste pigment that itself comes from the breakdown of biliverdin.

When there are pathological conditions whereby the colon is forced to discharge before it has completed the cycle of natural bacterial fermentation, biliverdin is unable to transform into bilirubin and therefore colors the stool, which turns greenish (sometimes, even very green).

These are often conditions of diarrhea, caused by bacterial or viral infections of the colon or by laxative abuse.

Sometimes, however, particularly greenish stools are not due to a pathological condition but are the result of a diet very rich in foods that are themselves rich in chlorophyll, such as leafy greens (spinach, chard, broccoli, etc.), parsley, chicory, and green leafy vegetables in general;

Orange stool

Particularly orange stools may indicate a diet very rich in carotenoid pigments, including beta-carotene found naturally in carrots, pumpkin, mango, some types of potatoes, apricots, etc.

Sometimes this color is given by taking certain antifungal drugs such as rifampin, or by ingesting food dyes;

Yellow or very pale stools

Yellow and particularly foul-smelling stools may indicate a problem with intestinal malabsorption, with reduced bacterial fermentation and acidification of the alvus itself.

This is almost always an ongoing bacterial or viral infection in the intestinal mucosa, which in turn causes frequent bouts of acute diarrhea and the emission of unformed, acidic stools with a pungent and sometimes nauseous odor.

When the color is very light yellow, almost faded, the stool may indicate serious liver problems, which has caused bilirubin not to reach the intestines.

This can occur, for example, in the case of gallstones, a serious pancreatic problem (e.g., pancreatic carcinoma) or cirrhosis, hepatitis or liver cancer.

The feces of celiac patients who have accidentally ingested gluten and thus triggered the violent autoimmune reaction of the intestine are very pale, greasy, and nauseous smelling.

It should be reiterated that this list is only an outline, for informational purposes only: stool color can change for a wide range of causes and concurrences, and is not always indicative of a pathological condition.

Small changes in stool color that occur on a daily basis should not worry or alarm: it is normal, and as mentioned it depends on both the activity of the gut microbiome and the type of diet.

Instead, the patient should become active when there is a radical and lasting change in stool output, especially if it is associated with other symptoms or physical conditions.

Take care of your gut microbiome-your well-being depends on it!

As you may have realized from reading this article, the color of your stool and, in general, your state of well-being not only of your intestines but of your entire body is dependent on the proper balance of your intestinal flora with your gut.

The intestinal bacterial flora is an integral part of the colon and, generally speaking, of our entire gut: its presence is imperative to stay well, and to successfully complete our digestion.

The symbiont bacteria living in our intestines should be considered a true auxiliary organ, indispensable not only for proper evacuation, but also for the synthesis of chemical elements essential for our survival.

That is why we should all strive to maintain a varied and balanced diet, avoiding foods that can damage the intestinal flora and inflame the mucosa, since the condition of well-being involves perfect harmony between bacteria and the colon.

Likewise, we should all keep in check the level of stress, anxiety and anger, which we can unfortunately experience on a daily basis: increased stress and tension forces our brains to produce large amounts of cortisol.

Cortisol is a hormone that calms and relaxes all non-vital or essential functions of our body, allowing us to self-heal, but it has a deleterious effect on the colon, particularly on our intestinal flora.

In fact, cortisol inflames the mucosa of the intestine and severely damages friendly bacteria, which is one reason why many people 'somatize' anxiety and stress situations with sudden discharges of diarrhea, cramps and intestinal spasms, or sudden periods of constipation.

This effect of cortisol on the gut is one of the plausible explanations for irritable bowel syndrome, for example.

Controlling periods of stress, attempting to live pleasantly, taking good care of both work but also social relationships, and generally taking care of oneself helps to lower cortisol levels, and thus feel better from a gut perspective.

Do you need a Proctologist Surgeon in Dubai? Dr. TROYER is here to help you

Dr. Luisella Troyer is a Proctology Surgeon who has been caring for your intestines and your daily well-being for more than 30 years.

If you experience major changes in your bowel, you can reach Dr. Troyer for a specialized proctological examination.

Dr. Troyer can help you heal your gut and stay well, thanks to advanced Colonproctology and phytotherapy-based natural cures, which often prove incredibly effective in rebalancing unhealthy gut situations without the use of invasive drugs.