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(Anatomy) Digestive System: Bacteria Thrive in Human Bellies

 
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PostPosted: Thu Jan 05, 2006 1:28 pm    Post subject: (Anatomy) Digestive System: Bacteria Thrive in Human Bellies Reply with quote






Bacteria Thrive in Hostile Human Bellies
By Ker Than
LiveScience Staff Writer
posted: 05 January 2006
09:06 am ET

The harsh acidic environment of your stomach is home to many more bacteria types than previously thought, a new study indicates.

One newly identified creature in your belly is related to a species that's considered one of the hardiest organisms on the planet, a bacterium that eats radioactive wastes for lunch.

The human stomach is a pear-shaped chamber filled with a highly noxious cocktail of hydrochloric acid and protein-cleaving digestive enzymes called peptidases. This gastric soup can have a pH of 1 to 3; the pH scale goes from 1 to 14 with a lower number indicating more acidity.

The stomach protects itself from its own corrosive juices by coating its interior with a thick, continually secreted layer of mucous.

New gastric view

The medical community long believed that pretty much nothing from the outside could survive in the stomach's harsh environment. That view began to change in 1982, when two Australian scientists, Robin Warren and Barry Marshall, found spiral-shaped bacteria called Helicobacter pylori in human stomachs.

The two researchers hypothesized that h. pylori was responsible for stomach inflammation, also called gastritis, and ulcers. Doctors traditionally thought these ailments were caused by stress or spicy foods.

Later experiments—including one where Marshal actually gave himself gastritis by drinking an h. pylori broth—confirmed their suspicions, and both Warren and Marshall were awarded the 2005 Nobel Prize in Medicine for their discovery.

Since then, however, only a few other bacteria types have ever been found in the stomach.

In the new study, researchers extracted snippets of genetic material from the stomachs of 19 people and found the biological blueprints of 128 bacteria types. Many of them had never been observed in the stomach before and 10 percent were previously unknown to science.

Conan the bacterium

One of the newly discovered bacteria types is a relative of Deinococcus radiodurans, one of the hardiest organisms alive.

D. radiodurans is a so-called extremophile because it thrives in extreme environments that would kill most organisms, such as radioactive waste dumps and hot springs. While a radiation dose of 10 grays (Gy) would kill a human, D. radiodurans can take up to 5,000 Gy with no visible effect. It can survive heat, cold, vacuum, and acid. It is so resilient scientists nicknamed it "Conan the Bacterium," after the fictional barbarian warrior.

It's unclear, however, whether the new D. radiodurans relative is likewise resistant to radiation, said David Relman, a microbiologist and immunologist at Stanford University and principal investigator in the study.

"This thing could be a totally different and novel bacteria, but only because its closest relative is famous for being incredibly radioresistant would we even think this one might be as well," Relman told LiveScience.

Relman said the next step is to observe the stomachs of volunteers over time to determine whether the newly identified stomach bacteria actually live there or whether they're just passing through.

"It could be possible that we have a continuous flow of organisms through the stomach and that very few of these are staying put," Relman said.

The study, lead by Elisabeth Bik of Stanford University, was detailed in a January online version of the journal for the Proceedings of the National Academy of Sciences.

*************************************************************

Questions to explore further this topic:

An overview of the digestive system:

http://arbl.cvmbs.colostate.ed.....rview.html

What is the digestive system?

http://kidshealth.org/kid/body/digest_noSW.html
http://kidshealth.org/parent/g.....stive.html
http://yucky.kids.discovery.co.....00126.html
http://www.innerbody.com/image/digeov.html
http://biology.clc.uc.edu/cour.....gestiv.htm
http://www.umm.edu/digest/howworks.htm

How does the digestive system work?

http://digestive.niddk.nih.gov.....pubs/yrdd/

Parts of the digestive system:

http://arbl.cvmbs.colostate.ed.....atomy.html
http://www.harcourtschool.com/activity/digest/
http://www.tvdsb.on.ca/westmin.....igdiag.htm
http://vilenski.org/science/hu.....ystem.html
http://www.sirinet.net/~jgjohnso/digestsys.html

Microorganisms in the digestive system:

http://arbl.cvmbs.colostate.ed....._bugs.html

The digestion process:

Pregastric Digestion

http://library.thinkquest.org/5777/dig2.htm
http://arbl.cvmbs.colostate.ed.....index.html

The Stomach
http://library.thinkquest.org/5777/dig3.htm
http://arbl.cvmbs.colostate.ed.....index.html

The Liver
http://arbl.cvmbs.colostate.ed.....index.html

The Pancreas
http://arbl.cvmbs.colostate.ed.....index.html

The Small Intestine
http://arbl.cvmbs.colostate.ed.....index.html

The Large Intestine
http://arbl.cvmbs.colostate.ed.....index.html

The End
http://www.kidshealth.org/kid/.....bowel.html

Diseases of the Digestive System:

http://www.healthsquare.com/fgpd/fg4ch05p2.htm
http://www.baptistonline.org/h.....estive.asp
http://www.mic.ki.se/Diseases/C06.html

The Digestive System of Plant-eaters

http://arbl.cvmbs.colostate.ed.....index.html

The Digestive System of Birds

http://arbl.cvmbs.colostate.ed.....index.html

GAMES

http://www.teachnutrition.org/ie/kids/voyage.html
http://www.vtaide.com/png/digest-mcq.htm
http://www.aliveis.com/main.html
http://www.exhibits.pacsci.org....._cafe.html


Last edited by adedios on Sat Jan 27, 2007 4:35 pm; edited 2 times in total
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PostPosted: Mon Sep 18, 2006 1:47 pm    Post subject: Road wends its way through stomach Reply with quote

Penn State
18 September 2006
Road wends its way through stomach

A computer model or "virtual stomach" revealed a central "road" in the human stomach, dubbed the Magenstrasse, that could explain why pharmaceuticals sometimes have a large variability in drug activation times, according to a team creating computer simulations of stomach contractions.

"We are predicting variables that we wish we could measure, but we cannot," says Dr. James G. Brasseur, professor of mechanical engineering, bioengineering and mathematics at Penn State. "Now that we know the Magenstrasse exists, we can look for it, but, it will not be easy to measure its existence and could require expensive technology."

Brasseur, working with Anupam Pal, research associate, Penn State and Bertil Abrahamsson, AstraZeneca, was interested in how the stomach empties its contents and how material passes from the stomach into the small intestines.

"The sphincter between the stomach and the small intestine is interactive," said Brasseur. "The sphincter opens and closes in a controlled way to regulate the flow of nutrient to the small intestines. Sensor cells in the intestines modulate the opening and closing."

Two types of muscle contractions control food movement in the stomach. One type of contraction, antral contractions, occur in the lower portion of the stomach and break down and mix stomach contents. The other type of contraction, fundic contractions, is over the upper surface of the stomach. It was thought that the fundic contractions move food from the top of the stomach where it enters from the esophagus, to the bottom of the stomach where the chyme leaves and enters the small intestine. The assumption was that particles left the stomach in the same order they entered the stomach.

The researchers modeled the stomach contents and discovered that a narrow path forms in the center of the stomach along which food exits the stomach more rapidly than the regions near the walls of the stomach. They used MRI data from human subjects to create the proper geometry of the muscle contractions.

"We looked at a ten-minute window of digestion and we tagged all the particles as they left the virtual stomach," said Brasseur. "We then reversed the flow on the computer and saw where the particles came from."

In essence they ran the simulation backwards and were surprised to see a central road appear. Those particles in the virtual stomach that were on the central road, exited the stomach in 10 minutes. The Magenstrasse extended all the way from the stomach's exit up to the top of the stomach's fundus. Material that entered the stomach off this Magenstrasse could remain in the stomach a long time, even hours in the real stomach.

"This discovery might explain observed high variability in drug initiation time, and may have important implications to both drug delivery and digestion," the researchers report online in the Journal of Biomechanics. The paper will appear in a print edition in 2007.

Because most drugs target the small intestines for absorption, a pill disintegrates in the stomach and activates in the small intestines. With this new understanding of how the stomach works, where in the stomach a pill or capsule disintegrates becomes very important. Drug delivery times may differ from 10 minutes to hours depending on location.

"Therefore, drugs released on the Magenstrasse will enter the duodenum rapidly and at a high concentration," the researchers report. "Drug released off the gastric emptying Magenstrasse, however, will mix well and enter the duodenum much later, at low concentration."

For some drugs, rapid release is important, for others, slow release over long periods of time is the desired outcome.

"If you do not know a Magenstrasse exists, you will not factor it into the designs," says Brasseur. "Now that we know, perhaps researchers can design pills with higher densities to sit around at the bottom of the stomach, outside the Magenstrasse, and let the drug out slowly."
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PostPosted: Tue May 22, 2007 9:51 am    Post subject: GI screening: Racing time or wasting time? Reply with quote

American Gastroenterological Association
22 May 2007

GI screening: Racing time or wasting time?
What doctors should consider in detection and prevention measures

WASHINGTON, D.C. (May 22, 2007) — Preventative medicine and technology are some of the great benefits in this ever-changing age of health care technology. Operations that once required major surgery and in-patient stays are being replaced with minimally invasive procedures with quick recovery times. Among these preventative technologies include CT scans, colonoscopies and X-rays. But with all of these available options in detecting abnormalities in patients, how does one choose which test to perform and whether it is worth the time to test on fast-acting ailments" Research presented today at Digestive Disease Week® 2007 (DDW®) provides guidance as to which tests are best for which patients. DDW is the largest international gathering of physicians and researchers in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

"The findings from these studies direct doctors as to what measures are most effective in treating their patients," said Gregory Ginsberg, M.D., AGAF, University of Pennsylvania Health System. "Whether the patient's condition is acute or chronic, detection and time are crucial factors in patient outcome."

Computed Tomography in Diagnosis of Acute Appendicitis: Definite or Detrimental" (Abstract #625)

It can be difficult to assess whether a patient is experiencing acute appendicitis or has an intestinal upset. CT, or computed tomography, scans can help determine if the patient needs to have his or her appendix removed. However, while having a clear picture showing the appendix confirms patient and physician suspicions, the time required to conduct the scan delays time to a potential operation, with the risk that the appendix could perforate while the patient awaits the test results. Researchers at the University of Wisconsin in Madison, Wis. evaluated the differences between patients who received a CT scan before removal of their appendix and those who went directly to surgery without the test.

In this study, investigators reviewed the hospital records for 412 adult patients admitted to University of Wisconsin Hospital during a three-year period. The researchers compared the white blood cell counts taken from patients both upon arrival to the emergency room and at the operating room. Of the 410 patients showing signs of acute appendicitis, more than half (62%) had a CT scan before the removal of their appendix.

Patients who were ordered a CT scan were older, more likely to be female and had experienced a longer waiting period between admittance and surgery than those who were not ordered a scan (8.2 vs. 5.1 hours). Additionally, perforation was seen in 17 percent of those who had a CT scan, while only eight percent of those who did not get a CT scan experienced perforation.

"These findings suggest that pre-operative CT scanning in patients experiencing acute appendicitis symptoms should be used selectively," said Herbert Chen, M.D., of University of Wisconsin and lead author of the study. "CT imaging may delay surgery, increasing the likelihood of the appendix rupturing and causing potentially dangerous complications for the patient."

Dr. Sandeepa Musunuru will present this study on Tuesday, May 22, at 10:30 a.m. in Room 202A.

The Utilization of Colonoscopy as a Screening Method For Colorectal Cancer: The Experience of Two U.S. Metropolitan Teaching Hospitals with Significant Documented Racial Differences in The Prevalence and Distribution of Advanced Neoplastic Lesions (Abstract #595)

When screening for colorectal cancer, there are many different test options; however, there has been no consensus on the most appropriate screening method for specific subsets of patients. In this study, researchers evaluated tests to detect advanced neoplastic lesions (lesions with high risk of progression to cancer or actual cancer), seeking to identify possible racial disparities between Caucasian and African American patients in detecting and diagnosing colorectal cancer, as well as the usefulness of colonoscopies in detecting colorectal cancer in patients without cancerous symptoms.

Investigators reviewed 16,737 colonoscopies performed at Emory University Hospital and Grady Memorial Hospital between January 2000 and December 2005. Colonoscopies give clearer pictures of bends in the colon than another screening tool called flexible sigmoidoscopy, which uses a slender hallow lighted tube to detect cancer. Researchers studied procedure results for abnormally sized and shaped polyps and adenomas (benign tumors) larger than 10 millimeters.

One-third (n=5,597) of the patients screened had an average risk for colorectal cancer and eight percent (n=462) were confirmed to have advanced neoplastic lesions. For more than half of the patients with advanced neoplastic lesions (57%, n=262), the lesions were confined to the proximal colon, making it very difficult for the flexible sigmoidoscopy to detect. Notably, Caucasian patients had a higher risk for proximal tubular adenoma while African American patients had a higher risk for proximal adenocarcinoma and proximal tubulovillous adenoma. Tubulovillous adenomas have a higher rate of progression to cancer. There was a trend towards females having more advanced neoplastic lesions. However, this was not statistically significant.

"These results direct doctors to perform colonoscopies rather than other methods, such as the flexible sigmoidoscopy, as they detect more colon tumors that may have been missed with flexible sigmoidoscopy," said Mohammed A. Wehbi, M.D., of Emory University in Atlanta, Ga., and lead author of this study. "Additionally, the study shows racial differences in detecting and diagnosing advanced neoplastic lesions/cancer, suggesting a possible need for earlier and more aggressive screening of African American patients."

Dr. Wehbi will present this study on Tuesday, May 22, at 9:30 a.m. in Room 206.


###
Digestive Disease Week® (DDW®) is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. Jointly sponsored by the American Association for the Study of Liver Diseases (AASLD), the American Gastroenterological Association (AGA) Institute, the American Society for Gastrointestinal Endoscopy (ASGE) and the Society for Surgery of the Alimentary Tract (SSAT), DDW takes place May 19-24, 2007 in Washington, D.C. The meeting showcases more than 5,000 abstracts and hundreds of lectures on the latest advances in GI research, medicine and technology.
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PostPosted: Fri Aug 10, 2007 2:14 pm    Post subject: Investigators uncover intriguing clues to why persistent aci Reply with quote

UT Southwestern Medical Center

Investigators uncover intriguing clues to why persistent acid reflux sometimes turns into cancer

DALLAS – Aug. 10, 2007 – New research from scientists at UT Southwestern Medical Center and the Dallas Veterans Affairs Medical Center underscores the importance of preventing recurring acid reflux while also uncovering tantalizing clues on how typical acid reflux can turn potentially cancerous.

In research published in July and August, scientists discovered that people with acid reflux disease, particularly those with a complication of acid reflux called Barrett’s esophagus, have altered cells in their esophagus containing shortened telomeres, the ending sequences in DNA strands. Combined with related research to be published this month, the findings indicate that the shortened sequences might allow other cells more prone to cancer to take over.

“The research supports why it is important to prevent reflux, because the more reflux you have and the longer you have it, the more it might predispose you to getting Barrett’s esophagus. So you want to suppress that reflux,” said Dr. Rhonda Souza, associate professor of internal medicine at UT Southwestern and lead author of the paper which appears in the July issue of the American Journal of Physiology – Gastrointestinal and Liver Physiology.

Heartburn occurs when acid splashes back up from the stomach into the esophagus, the long feeding tube that connects the stomach and throat, causing a burning sensation.

Over time, the persistent acid bath can cause normal skin-like cells in the esophagus to change into tougher, more acid-resistant cells of the type found in the stomach and intestine, a condition called Barrett’s esophagus, explained Dr. Stuart Spechler, professor of internal medicine and senior author of the paper. “Unfortunately, those acid-resistant cells are also more prone to cancer,” Dr. Spechler said.

Adenocarcinoma of the esophagus, the cancer that is especially associated with Barrett’s esophagus, is currently the most rapidly rising cancer in the U.S., with a sixfold increase in cases during the past 30 years, according to the National Cancer Institute.

Understanding how and why the cells change in some cases and not others has been a major challenge for investigators.

Researchers compared telomere length and telomerase activity in biopsy specimens from 38 patients with GERD and 16 control patients. This new line of research suggests that the continuous acid bath affecting esophageal cells causes them to divide more frequently in order to regenerate the damaged lining. However, each time the cells divide, the telomeres at the end of DNA become shorter. When they become too short, the aging cell can no longer divide, Dr. Souza said.

Scientists suspect that when cells can no longer divide, other cells might infiltrate the area to make up for the loss. And those cells may be more likely to generate the acid-resistance that makes them more likely to turn cancerous.

“If the telomeres get short enough, maybe the cells can’t regenerate any more and maybe that’s why you start to see this change,” said Dr. Spechler. “Perhaps the esophagus can’t regenerate the normal skin-like squamous cells, and instead, it has to recruit cells from somewhere else and that’s why you start getting these changes to intestinal-like cells.”

Other studies by this group of UT Southwestern digestive disease specialists suggest the alternate cells that eventually take over might be bone-marrow cells.

“There could be cells circulating from the bone marrow that wouldn’t ordinarily end up in the esophagus. But if you shorten the telomeres enough and the esophagus can’t regenerate anymore, perhaps these bone-marrow cells might have to replace that tissue, and bone-marrow cells can turn into intestinal tissue,” Dr. Spechler said. “This hasn’t been proven, but we have some data that supports that.”

In research available online prior to printing this month in Diseases of the Esophagus, Drs. Souza, Spechler and colleagues demonstrate that bone-marrow cells come into play to regenerate the esophageal lining in rats that have heavy reflux.

“So the first paper shows that the telomeres are short, suggesting that the normal squamous cells might not be able to divide anymore, so they die out,” Dr. Spechler said. “The second paper suggests that the bone-marrow cells may then come and take their place, giving rise to the intestinal cells instead of the normal, skin-like cells.”

Further research will be needed to confirm that hypothesis, Dr. Souza said.

“It’s an interesting series of experiments,” she said. “None of them absolutely prove that this is what’s going on, but it’s an interesting concept, and it certainly supports the theory that your normal cells poop out and eventually they can’t replace the damaged ones, and maybe that’s why you get Barrett’s esophagus.”

If confirmed, the research might also help scientists find a way to prevent the bone-marrow cells from invading or to identify markers that would allow an earlier diagnosis for Barrett’s esophagus, which doesn’t usually have symptoms.


###
Other UT Southwestern researchers involved in the studies are Dr. Jerry Shay, vice chairman of cell biology, and Dr. Geri Brown, associate professor of internal medicine. In addition, researchers from the University of Florida, Texas Tech University Health Science Center in El Paso and the Mayo Clinic also participated.

The research was funded by the Department of Veteran’s Affairs, National Institutes of Health, the Harris Methodist Health Foundation, the Dr. Clark R. Gregg Fund and AstraZeneca.

This news release is available on our World Wide Web home page at http://www.utsouthwestern.edu/.....99253.html

To automatically receive news releases from UT Southwestern via e-mail, subscribe at www.utsouthwestern.edu/receivenews

Dr. Rhonda Souza - http://www.utsouthwestern.edu/.....45,00.html

Dr. Stuart Spechler - http://www.utsouthwestern.edu/.....56,00.html
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PostPosted: Thu Aug 23, 2007 9:19 am    Post subject: Gut Sense: Your Belly Has Taste Reply with quote

Gut Sense: Your Belly Has Taste
By Jeanna Bryner, LiveScience Staff Writer

posted: 23 August 2007 08:32 am ET

Savory snacks are not only a treat for the mouth, but now scientists find the tummy can also say "yummy."

A new study shows that the same sweet-detecting proteins in your tongue also reside in the gut where they can likewise "taste" sugars.

"Cells of the gut taste glucose through the same mechanisms used by taste cells of the tongue," said study author Robert Margolskee, a neuroscientist at Mount Sinai School of Medicine in New York.

For the full article:

http://www.livescience.com/hea.....belly.html
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PostPosted: Mon Oct 08, 2007 2:53 pm    Post subject: Appendix isn't useless at all: It's a safe house for bacteri Reply with quote

Duke University Medical Center
8 October 2007

Appendix isn't useless at all: It's a safe house for bacteria

DURHAM, N.C. – Long denigrated as vestigial or useless, the appendix now appears to have a reason to be – as a “safe house” for the beneficial bacteria living in the human gut.

Drawing upon a series of observations and experiments, Duke University Medical Center investigators postulate that the beneficial bacteria in the appendix that aid digestion can ride out a bout of diarrhea that completely evacuates the intestines and emerge afterwards to repopulate the gut. Their theory appears online in the Journal of Theoretical Biology.

“While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed,” said William Parker, Ph.D., assistant professor of experimental surgery, who conducted the analysis in collaboration with R. Randal Bollinger, M.D., Ph.D., Duke professor emeritus in general surgery.

The appendix is a slender two- to four-inch pouch located near the juncture of the large and small intestines. While its exact function in humans has been debated by physicians, it is known that there is immune system tissue in the appendix.

The gut is populated with different microbes that help the digestive system break down the foods we eat. In return, the gut provides nourishment and safety to the bacteria. Parker now believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria.

For the past ten years, Parker has been studying the interplay of these bacteria in the bowels, and in the process has documented the existence in the bowel of what is known as a biofilm. This thin and delicate layer is an amalgamation of microbes, mucous and immune system molecules living together atop of the lining the intestines.

“Our studies have indicated that the immune system protects and nourishes the colonies of microbes living in the biofilm,” Parkers explained. “By protecting these good microbes, the harmful microbes have no place to locate. We have also shown that biofilms are most pronounced in the appendix and their prevalence decreases moving away from it.”

This new function of the appendix might be envisioned if conditions in the absence of modern health care and sanitation are considered, Parker said.

“Diseases causing severe diarrhea are endemic in countries without modern health and sanitation practices, which often results in the entire contents of the bowels, including the biofilms, being flushed from the body,” Parker said. He added that the appendix’s location and position is such that it is expected to be relatively difficult for anything to enter it as the contents of the bowels are emptied.

“Once the bowel contents have left the body, the good bacteria hidden away in the appendix can emerge and repopulate the lining of the intestine before more harmful bacteria can take up residence,” Parker continued. “In industrialized societies with modern medical care and sanitation practices, the maintenance of a reserve of beneficial bacteria may not be necessary. This is consistent with the observation that removing the appendix in modern societies has no discernable negative effects.”

Several decades ago, scientists suggested that people in industrialized societies might have such a high rate of appendicitis because of the so-called “hygiene hypothesis,” Parker said. This hypothesis posits that people in "hygienic" societies have higher rates of allergy and perhaps autoimmune disease because they -- and hence their immune systems -- have not been as challenged during everyday life by the host of parasites or other disease-causing organisms commonly found in the environment. So when these immune systems are challenged, they can over-react.

“This over-reactive immune system may lead to the inflammation associated with appendicitis and could lead to the obstruction of the intestines that causes acute appendicitis,” Parker said. “Thus, our modern health care and sanitation practices may account not only for the lack of a need for an appendix in our society, but also for much of the problems caused by the appendix in our society.”

Parker conducted a deductive study because direct examination the appendix’s function would be difficult. Other than humans, the only mammals known to have appendices are rabbits, opossums and wombats, and their appendices are markedly different than the human appendix.

Parker’s overall research into the existence and function of biofilms is supported by the National Institutes of Health. Other Duke members of the team were Andrew Barbas, Errol Bush, and Shu Lin.
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PostPosted: Wed Jan 09, 2008 12:03 pm    Post subject: Down to earth remedies for chimps Reply with quote

Heidelberg, 8 January 2008
Springer

Down to earth remedies for chimps

Study suggests chimpanzees ingest soil to enhance anti-malarial properties of plants

The deliberate ingestion of soil, or ‘geophagy’, has important health benefits for chimpanzees, according to Sabrina Krief and her colleagues from the Muséum National d’Histoire Naturelle in Paris, France. Far from being a dysfunctional behavior, geophagy has evolved as a practice for maintaining health amongst chimpanzees. In this particular study (1), to be published online this week in Springer’s journal Naturwissenschaften, geophagy increases the potency of ingested plants with anti-malarial properties.

Although geophagy is widespread throughout the animal kingdom, in humans it is perceived as a curious behavior, even linked by some to mental health issues. The paper looks at the consequences of soil ingestion on the health status of chimpanzees in the Kibale National Park in Uganda. These chimpanzees have been observed to ingest soil shortly before or after consuming plant parts, such as the leaves of Trichilia rubescens, which have anti-malarial properties in the laboratory.

The research team collected fourteen samples of soil eaten by chimpanzees as well as T. rubescens leaves from young trees in the same area. They designed a digestion model to replicate the digestive process of mastication, gastric and intestinal digestion in the laboratory. The samples were then analyzed for bioactive properties. The soil and leaves were examined both individually and as a mixture.

Before being mixed with the soil, the digested leaves showed no significant anti-malarial activity. However, when the leaves and soil were digested together, the mixture had clear anti-malarial properties.

The researchers also compared the composition of the soil eaten by chimpanzees with the content of soil used by the local healer to treat diarrhea amongst his patients. All the soil samples were rich in the clay mineral kaolinite, the principal component of some anti-diarrheal medicines. Furthermore, samples used by chimps and humans had exactly the same external aspects, were collected in a similar place and show a comparable physical and chemical profile, indicating similar content.

On the basis of these observations, Krief commented, “This overlapping use by humans and apes is interesting from both evolutionary and conservation perspectives - saving apes and their forests is also important for human health.”

Krief and her colleagues discount mineral supplementation, stress-induced behavior and the search for anti-diarrheal effects of clay as the reasons behind the chimpanzees’ geophagy observed at the field site during this study period. They propose geophagy’s ability to enhance the pharmacological properties of plants as a novel argument to explain motivation for chimpanzees to ingest soil. They conclude that geophagy is a practice for maintaining health which may explain why it has persisted through evolution.

Reference
1. Krief S, Klein N & Fröhlich F (2008). Geophagy: soil consumption enhances the bioactivities of plants eaten by chimpanzees. Naturwissenschaften (DOI 10.1007/s00114-007-0333-0)
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