Feces or Stool

 Feces or Stool

Introduction

Human feces or faeces is the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has been further broken down by bacteria in the large intestine. It also contains bacteria and a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and the dead epithelial cells from the lining of the gut. It is discharged through the anus during a process called defecation. In the medical literature, the term stool is more commonly used than feces.

The feces normally are about three-fourths water and one-fourth solid matter that is composed of about 30 percent dead bacteria, 10 to 20 percent fat, 10 to 20 percent inorganic matter, 2 to 3 percent protein, and 30 percent undigested roughage from the food and dried constituents of digestive juices, such as bile pigment and sloughed epithelial cells.

The brown color of feces is caused by stercobilin and urobilin, derivatives of bilirubin. The odor is caused principally by products of bacterial action; these products vary from one person to another, depending on each person’s colonic bacterial flora and on the type of food eaten. The actual odoriferous products include indole, skatole, mercaptans, and hydrogen sulfide.

Types

The Bristol stool scale is a medical aid designed to classify the form of human feces into seven categories. Sometimes referred to in the UK as the Meyers Scale, it was developed by K.W. Heaton at the University of Bristol and was first published in the Scandinavian Journal of Gastroenterology in 1997. It is based on the fact that the form of the stool depends on the time it spends in the colon.

The seven types of stool are:

1.     Separate hard lumps, like nuts (hard to pass)

2.     Sausage-shaped but lumpy

3.     Like a sausage but with cracks on the surface

4.     Like a sausage or snake, smooth and soft

5.     Soft blobs with clear-cut edges

6.     Fluffy pieces with ragged edges, a mushy stool

7.     Watery, no solid pieces. Entirely liquid

Types 1 and 2 indicate constipation.

Types 3 and 4 are optimal, especially the latter, as these are the easiest to pass.

Types 5–7 are associated with increasing tendency to diarrhea or urgency.

Meconium is a newborn baby's first feces.

Color

Human fecal matter varies significantly in appearance, depending on diet and health.

Brown

Human feces ordinarily has a light to dark brown coloration, which results from a combination of bile, and bilirubin derivatives of stercobilin and urobilin, from dead red blood cells. Normally it is semisolid, with a mucus coating.

 Yellow

Yellowing of feces can be caused by an infection known as giardiasis, which derives its name from Giardia, an anaerobic flagellated protozoan parasite that can cause severe and communicable yellow diarrhea. Another cause of yellowing is a condition known as Gilbert's Syndrome. Yellow stool can also indicate that food is passing through the digestive tract relatively quickly. Yellow stool can be found in people with gastro esophageal reflux disease (GERD).

Pale or gray

Stool that is pale or grey may be caused by insufficient bile output due to conditions such as cholecystitis, gallstones, Giardia parasitic infection, hepatitis, chronic pancreatitis, or cirrhosis. Bile pigments from the liver give stool its brownish color. If there is decreased bile output, stool is much lighter in color.

Black

Melena- Feces can be black due to the presence of red blood cells that have been in the intestines long enough to be broken down by digestive enzymes. This is known as melena, and is typically due to bleeding in the upper digestive tract, such as from a bleeding peptic ulcer.

Conditions that can also cause blood in the stool include hemorrhoids, anal fissures, diverticulitis, colon cancer, and ulcerative colitis.

The same color change can be observed after consuming foods that contain a substantial proportion of animal blood.

Black feces can also be caused by a number of medications, such as bismuth subsalicylate and dietary iron supplements, or foods such as beetroot, black liquorice, or blueberries.

 Red

Hematochezia- is similarly the passage of feces that is bright red due to the presence of undigested blood, either from lower in the digestive tract, or from a more active source in the upper digestive tract. Alcoholism can also provoke abnormalities in the path of blood throughout the body, including the passing of red-black stool. Hemorrhoids can also cause surface staining of red on stools, because as they leave the body the process can compress and burst hemorrhoids near the anus.

Blue

Prussian blue, or blue, a coloring used in the treatment of radiation, cesium, and thallium poisoning, can turn the feces blue. Substantial consumption of products containing blue food dye, such as blue Curacao or grape soda, can have the same effect.

Silver

A tarnished-silver or aluminum paint-like feces color characteristically results when biliary obstruction of any type (white stool) combines with gastrointestinal bleeding from any source (black stool). It can also suggest a carcinoma of the ampulla of Vater, which will result in gastrointestinal bleeding and biliary obstruction, resulting in silver stool.

Green

Feces can be green due to having large amounts of unprocessed bile in the digestive tract and strong-smelling diarrhea. This can occasionally be the result from eating liquorice candy, as it is typically made with anise oil rather than liquorice herb and is predominantly sugar. Excessive sugar consumption or sensitivity to anise oil may cause loose, green stools. It can also result from consuming excessive amounts of blue or green dye.

Violet or purple

The violet or purple feces is a symptom of porphyria or more likely the consumption of beetroot.

Odor

Human feces possess a typical odor which can vary according to diet and health status. The odor of human feces is made up from the following odorant volatiles-

1.     Methyl sulfides

·        methylmercaptan/methanethiol (MM)

·        dimethyl sulfide (DMS)

·        dimethyl disulfide (DMDS)

·        dimethyl trisulfide (DMTS)

2.     Benzopyrrole compounds

·        indole

·        skatole

3.     Hydrogen sulfide (H₂S)

H₂S is the most common gaseous sulfur compound in feces. The odor of feces may be increased when various pathologies are present, including

·         Celiac disease

·         Crohn's disease

·         Ulcerative colitis

·         Chronic pancreatitis

·         Cystic fibrosis

·         Intestinal infection, e.g. Clostridium difficile infection

·         Malabsorption

·         Short bowel syndrome

Average chemical composition

On average humans eliminate 128 g of fresh feces per person per day with a pH value of around 6.6.

Fresh feces contains the following-

·        Water approximately	75%
·        Total solids approximately	25%

These solids consist of following matter-

Organic solids- 84–93%

·        Bacterial biomass	25-54%
·        Protein or nitrogenous matter	2-25%
·        Carbohydrate or undigested plant matter	25%
·        Fat	2-15%

Protein and fat come from the colon due to secretion, epithelial shedding and gut bacterial action. These proportions vary considerably depending on many factors mainly diet and body weight.

Inorganic solids- are composed of calcium and iron phosphates etc.

 

Undigested food remnants

Sometimes undigested food may make an appearance in feces. Common undigested foods found in human feces are seeds, nuts and corn, mainly because of their high fiber content. Beets may turn feces different hues of red. Artificial food coloring in some processed foods, such as highly colorful packaged breakfast cereals can cause an unusual coloring of feces if eaten in sufficient quantities.

Fecal bacteriotherapy/ fecal transplant

In humans, fecal transplants or stool transplant is the process of transplantation of fecal bacteria from a healthy individual into a recipient who has a certain disease, such as irritable bowel syndrome. The resulting inoculation of healthy gut flora can sometimes improve the physiology of the recipient gut.

Fecal bacteriotherapy also known as a fecal transplant is a medical procedure wherein fecal bacteria are transplanted from a healthy individual into a patient. 

Recent research indicates that this may be a valuable method to re-establish normal gut cultures that have been destroyed through the use of antibiotics or some other medical treatments.