Human feces
Human feces (or faeces in British English) are 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.[1][2] 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.[1] It is discharged through the anus during a process called defecation.
Human feces has similarities to the feces of other animals and varies significantly in appearance (i.e. size, color, texture), according to the state of the
In the medical literature, the term "stool" is more commonly used than "feces".[3]
Human feces together with human urine are collectively referred to as human waste or human excreta. Containing human feces, and preventing spreading of pathogens from human feces via the fecal–oral route, are the main goals of sanitation.
Characteristics
Classification
The Bristol stool scale is a
The seven types of stool are:
- Separate hard lumps, like nuts (hard to pass)
- Sausage-shaped but lumpy
- Like a sausage but with cracks on the surface
- Like a sausage or snake, smooth and soft
- Soft blobs with clear-cut edges
- Fluffy pieces with ragged edges, a mushy stool
- 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.[5]
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,[6] 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 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 gastroesophageal reflux disease(GERD).
Pale or gray
- Stool that is pale or grey may be caused by insufficient bile output due to conditions such as give stool its brownish color. If there is decreased bile output, stool is much lighter in color.
Black or red
- 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
- 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
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.[9]
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 a sensitivity to anise oil may cause loose, green stools.[10] It can also result from consuming excessive amounts of blue or green dye.
Violet or purple
- Violet or purple feces is a symptom of porphyria or more likely the consumption of beetroot.
Odor
Feces possesses physiological odor, which can vary according to diet and health status. For example, meat protein is rich in the amino acid methionine, which is a precursor of the sulfur-containing odorous compounds listed below.[11][12][13][14][15] The odor of human feces is suggested to be made up from the following odorant volatiles:[12]
- Methyl sulfides
- methylmercaptan/methanethiol (MM)
- dimethyl sulfide (DMS)
- dimethyl disulfide (DMDS)
- dimethyl trisulfide (DMTS)
- Benzopyrrole volatiles
- Hydrogen sulfide (H2S)
(H2S) is the most common volatile sulfur compound in feces.[12] The odor of feces may be increased when various pathologies are present, including:[16]
- Celiac disease
- Crohn's disease
- Ulcerative colitis[17]
- Chronic pancreatitis
- Cystic fibrosis
- Intestinal infection, e.g. Clostridium difficile infection.[18]
- Malabsorption
- Short bowel syndrome
Attempts to reduce the odor of feces (and
- Activated charcoal[19](In this study it was found that activated charcoal at a dose of 0.52g four times a day did not appreciably influence the liberation of fecal gases.)
- Bismuth subsalicylate[20]
- Chloryphyllyn
- Herbs such as rosemary
- Yucca schidigera[21]
- Zinc acetate[21]
Average chemical characteristics
On average, healthy humans eliminate 128 g of fresh feces per person per day with a
These organic solids consist of: 25–54% bacterial biomass, 2–25% protein or nitrogenous matter, 25% carbohydrate or undigested plant matter and 2–15% fat. Protein and fat come from the colon due to secretion, epithelial shedding and gut bacterial action. These proportions vary considerably depending on many factors but mainly diet and body weight.[23] The remaining solids are composed of insoluble calcium and iron phosphate salts, intestinal secretions, small amounts of dried epithelial cells, and mucus.[23]
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.
Undigested objects such as seeds can pass through the human digestive system, and later
Analytical tools
Stool analysis (stool sample)
Clinical laboratory examination of feces, usually termed as stool examination or
The main pathogens that are commonly looked for in feces include:
- Bacteroides species
- Salmonella and Shigella
- Yersinia tends to be incubated at 30 °C (86 °F), which is cooler than usual
- Campylobacter incubated at 42 °C (108 °F), in a special environment
- Aeromonas
- Candidaif the person is immunosuppressed (e.g., undergoing cancer treatment)
- E. coli O157 if blood is visible in the stool sample
- Cryptosporidium
- Entamoeba histolytica
Fecal markers
Feces can be analyzed for various markers that are indicative of various diseases and conditions. For example,
Reference ranges for fecal markers | |||||
---|---|---|---|---|---|
Marker | Patient type | Upper limit | Unit | ||
Calprotectin | 2–9 years | 166[24] | µg/g of feces | ||
10–59 years | 51[24] | ||||
≥ 60 years | 112[24] | ||||
Lactoferrin | 2–9 years | 29[24] | |||
≥ 10 years | 4.6[24] |
Also, feces may be analyzed for any fecal occult blood, which is indicative of a gastrointestinal bleeding.
Analysis of E. coli bacteria in water sources
A quick test for fecal contamination of water sources or soil is a check for the presence of E. coli bacteria performed with the help of MacConkey agar plates or Petri dishes. E. coli bacteria uniquely develop red colonies at temperature of approximately 43 °C (109 °F) overnight. Although most strains of E. coli are harmless, their presence is indicative of fecal contamination, and hence an increased possibility of the presence of more dangerous organisms.
Fecal contamination of water sources is highly prevalent worldwide, accounting for the majority of unsafe
), for example.Diseases and conditions
Diarrhea
Diarrhea (or diarrhoea in
It occurs when insufficient fluid is absorbed by the colon. As part of the digestion process, or due to fluid intake, food is mixed with large amounts of water. Thus, digested food is essentially liquid prior to reaching the colon. The colon absorbs water, leaving the remaining material as a semisolid stool. If the colon is damaged or inflamed, however, absorption is inhibited, and watery stools result.
Diarrhea is most commonly caused by a myriad of
Constipation
Constipation refers to
Others
Bile overload is very rare, and not a health threat. Problems as simple as serious diarrhea may cause blood in one's stool. Black stools caused by the presence of blood usually indicate a problem in the intestines (the black color is a sign of digested blood), whereas red streaks of blood in stool usually are caused by bleeding in the rectum or anus.
Uses
Use as fertilizer
Human feces has historically been used as
There are methods available to safely reuse human feces in
Fecal transplants
In humans, fecal transplants (or
Biogas production
The biogas produced from feces when it is contained in sewage and treated in an anaerobic digestion process could be worth as much as US$9.5 billion.[30]
Washington DC plans to produce biogas from
Paleofeces
Society and culture
Disgust and shame
In most human cultures, feces elicits varying degrees of disgust. Disgust is experienced primarily in relation to the sense of taste (either perceived or imagined) and, secondarily to anything that causes a similar feeling by sense of smell, touch, or vision. As such, human feces are regarded as something to be avoided diligently: expelled in private and disposed of immediately and without a trace. It often is considered an unacceptable topic in polite conversation and its mere mention may cause offence in certain contexts.
An example of repulsion by feces from the ancient world is found in the writings called Deuteronomy used by Jews and Christians:
Designate a place outside the camp where you can go to relieve yourself. As part of your equipment have something to dig with, and when you relieve yourself, dig a hole and cover up your excrement. For the LORD your God moves about in your camp to protect you and to deliver your enemies to you. Your camp must be holy, so that he will not see among you anything indecent and turn away from you.[34]
Evolution can explain this disgust since feces are a significant disease vector, carrying many kinds of microorganisms that can sicken humans, including E. coli.
Anal cleansing
People from different cultures employ a variety of personal cleansing practices after defecation. The
Terminology and other terms used
There are many synonyms in informal registers for human feces. Many are euphemistic, colloquial, or both; some are profane (such as shit), whereas most belong chiefly to child-directed speech (such as poo or poop) or to crude humor (such as turd).
Human feces together with human urine are collectively referred to as human waste or human excreta.
See also
References
- ^ ISBN 978-0-06-350729-6.
- ^ Diem K, Lentner C (1970). "Faeces". in: Scientific Tables (Seventh ed.). Basle, Switzerland: CIBA-GEIGY Ltd. pp. 657–60.
- ^ "Stool".
- PMID 9299672.
- ^ a b "Constipation Management and Nurse Prescribing: The importance of developing a concordant approach" (PDF). Archived from the original (PDF) on 5 July 2006. Retrieved 6 November 2006.
- ISBN 978-1-4160-4574-8.
- ^ Dugdale, David (1 November 2009). "Bloody or tarry stools". National Institutes of Health. Retrieved 30 November 2009.
- ^ "Fact Sheet: Prussian Blue". Centers for Disease Control and Prevention. 10 May 2006. Archived from the original on 20 October 2013. Retrieved 30 November 2009.
- ^ OpenStax CNX
- ^ Can Licorice Cause Discolored Stools? | livestrong.com
- PMID 2019366.
- ^ PMID 19505855.
- PMID 15206616.
- PMID 9274475.
- PMID 12854812.
- ^ Dugdale, David C. ""Stools – foul smelling" on Medline Plus". U.S. National Library of Medicine. Retrieved 21 October 2012.
- S2CID 3141574.
- PMID 18177217.
- S2CID 20729051.
- PMID 9558280.
- ^ PMID 11294313.
- PMID 22776285.
- ^ PMID 26246784.
- ^ S2CID 5396341.
- ^ "Diarrhoea". World Health Organization. Archived from the original on 23 August 2004.
- PMID 19647687.
- ^ WHO (2006). WHO Guidelines for the Safe Use of Wastewater, Excreta, and Greywater - Volume IV: Excreta and greywater use in agriculture. World Health Organization (WHO), Geneva, Switzerland
- ^ Rowan, Karen (20 October 2012). "'Poop Transplants' May Combat Bacterial Infections". Live Science. Retrieved 20 October 2012.
- PMID 21871249.
- ^ "Will the Future Be Powered by Feces? : DNews". DNews. Archived from the original on 4 March 2016. Retrieved 27 February 2016.
- ISSN 0190-8286. Retrieved 27 February 2016.
- ^ Khan, Izhan. "Project Report: The EvapoDryer". academia.edu. Retrieved 26 December 2019.
- PMID 11296282.
- The Bible, New International Version(NIV)
External links
- Media related to Human feces at Wikimedia Commons