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Functional intestinal disorders in adults

Functional Diahrrea

Functional diarrhea, characterized by very frequent bowel movements, often has no identified cause. Dysbiosis could be involved in the appearance of symptoms.  

Functional diarrhea is defined as the frequent or urgent evacuation of pasty or liquid stools, in an on-going or recurrent manner, with no identified cause. Isolated functional diarrhea should be distinguished from irritable bowel syndrome (IBS). The symptoms can be similar in both situations, but abdominal pain is predominant in IBS1,2. A French cohort study found that, in the general population, 1.1% to 1.5% of subjects had chronic diarrhea while 4.6% to 5.6% had irritable bowel syndrome3.

Knowing how to make a diagnosis

The most useful diagnostic exam is measuring the oro-anal transit time with carmine, which can confirm that transit is too fast. There can be hormonal causes (most often hyperthyroidism), neuropathic causes (diabetes)4 or even problems absorbing certain carbohydrates, but most often no cause is detected5. Some signs point to the role of dysbiosis and/or bacterial metabolism in the onset of symptoms.

Unbalanced microbiota

Significant differences in intestinal flora have been observed between patients and control subjects: a marked reduction in certain bacterial groups (Eubacterium rectale, Bacteroides, Faecalibacterium prausnitzii), elevated concentrations of mucotropic bacteria associated with deposits of mucus in feces, and an increase in the concentrations of occasional bacteria6 .

Probiotics and possible medication

Treatment with Saccharomyces boulardii corrected microbiota anomalies with partial (40%) or complete (30%) normalization of diarrhea6. There are various pharmacological treatments that are intended to slow intestinal transit.Diet needs to be controlled and products that accelerate transit, like alcohol7, must be eliminated. Reducing the intake of carbohydrates that are not properly absorbed in the intestine, like fructose and sorbitol, can improve patient health8, but no diet has been formally proven effective. 


1.    Thompson WG et al. Functional Bowel disorders and functional abdominal pain. In The Functional Gastrointestinal Disorders, Drossman DA ed, Degnon Ass., McLean VA, 2000, pp. 351-432.
2.    Tack J et al. Functional diarrhea. Gastroenterol Clin North Am. 2012 Sep;41(3):629-37. doi: 10.1016/j.gtc.2012.06.007. Epub 2012 Jun 28.
3.    D. Le Pluart et al. Functional gastrointestinal disorders in 35 447 adults and their association with body mass index. AP&T 2015 sep ; Vol. 41 (8) : 758–767 
4.    Azpiroz F et al. Diabetic neuropathy in the gut: pathogenesis and diagnosis. Diabetologia. 2016 Mar;59(3):404-8
5.    Diarrhée chronique par accéléraion du transit. SNFGE document publié en 1999
6.     Swidsinski A et al. Biostructure of fecal microbiota in healthy subjects and patients with chronic idiopathic diarrhea. Gastroen terology 2008 ; 135 : 568-79.
7.    Bouchoucha M et al.. Recovery from disturbed colonic transit time after alcohol withdrawal. Dis Colon Rectum 1991 ; 34 : 111-4
8.    Skoog SM, Bharucha AE. Dietary fructose and gastrointestinal symptoms : a review. Am J Gastroenterol 2004 ; 99 : 2046-50.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is characterized by painful disruptions in intestinal transit. In spite of its benign nature, it should not be neglected. 

IBS, or irritable colon, affects around 10% of the general population. It is characterized by a combination of chronic abdominal pain, bloating, transit disorders, and diarrhea or constipation, occurring at least one day per week over the last three months.1 The pathophysiology is still imperfectly understood and is based on a dysfunction in the communication between the central nervous system and the enteric nervous system, known as the gut-brain axis.2 This causes intestinal dysmotility and promotes the onset of visceral hypersensitivity. 

Altered microbiota

Arguments that indirectly connect these disruptions with qualitative, quantitative, or functional anomalies of the microbiota are becoming much more solid. Cases of IBS appear after an acute infection disrupts the microbiota.3 Diseases presenting with more significant and rapid production of hydrogen and/or methane after a normal meal suggest the presence of functionally different intestinal flora. Compared with healthy subjects, a less microbiota diverse was observed, with an excess of certain Clostridia and Firmicutes (Veillonella) and a reduction in bifidobacteria or bacterial proliferation in the proximal small intestine.4 Dysbiosis promotes alterations in the intestinal barrier and the onset of low-grade inflammation. This is followed by visceral hypersensitivity.

Setting therapeutic goals

Goals are based on largely symptomatic treatment: antispasmodics for bloating, laxatives for constipation, and antidiarrheals for diarrhea. If those fail, antidepressants may be indicated, particularly in painful cases1

Probiotics and a healthy diet

Some probiotics could present benefits1,5,6. Their effectiveness depends on which strain is administered, the dose, and the form used, and it cannot be extrapolated to other circumstances1Bifidobacterium infantis has been shown to be effective in patients with IBS5,6. This strain acts on the gastrointestinal microbiota, has an anti-inflammatory activity, and reduces visceral hypersensitivity7,8,9. Physical activity can also be beneficial, as well as a diet low in FODMAP. Standard healthy eating is largely recommended.

Pro - Anomalies physiopathologiques - EN
Pro - liens physiopathologiques - EN

1.    Jean-Marc Sabaté JM, Pauline Jouët. Prise en charge du Syndrome de l’Intestin Irritable (SII), septembre 2016. Société Nationale Française de Gastro-Entérologie. (
2.    Camilleri M. Peripheral mechanisms in irritable bowel syndrome. N Engl J Med 2012 ; 367 : 1626-35.
3.    Spiller R, Garsed K. Postinfectious irritable bowel syndrome. Gastroenterology 2009 ; 136 : 1979-88
4.    Parkes GC  et al. Distinct microbial populations exist in the mucosa associated microbiota of subgroups of irritable bowel syndrome. Neurogastroenterol Motil 2012 ; 24 : 31-39.
5.    Quigley EM. et al. World Gastroenterology Organisation Global Guidelines Irritable Bowel Syndrome: A Global Perspective Update September 2015. J Clin Gastroenterol. 2016;50:704-13.
6.    Brenner DM, Chey WD. Bifidobacterium infantis 35624: a novel probiotic for the treatment of irritable bowel syndrome. Rev Gastroenterol Disord 2009 ; 9 : 7-15.

Functional bloating

Functional bloating can be isolated. Excessive gas production can be linked to modifications of the intestinal microbiota.

Intestinal bloating is one of the most frequent functional digestive symptoms and is often the underlying reason for consulting a doctor. In 1998, a SOFRES inquiry including 4,817 adults revealed that 47% of the participants complained of abdominal bloating1 and that 59% of the participants reported that they were regularly bothered by passing gas (flatulence). Bloating is a feeling of distension in the abdominal wall, sometimes associated with the development of abdominal obesity for overweight subjects, but more often with abdominal discomfort associated with regular flatulence2.

Multiple causes

Several causes may be responsible for bloating: intestinal obstruction, like a tumor or abdominal adhesion, intestinal malabsorption (particularly celiac disease), a diet rich in legumes (white kidney beans, peas, lentils, etc.), sedentary lifestyle, etc. Bloating is sometimes associated with abdominal pain, making it one of the symptoms of irritable bowel syndrome (IBS), and its management is that of IBS2

Bacteria in the small intestine

Even though the colon is most often affected, bloating can also be caused by proliferation of intestinal bacteria in the small intestine4 or by dysbiosis, that promotes gas production5. Methanogenesis is ensured by the activity of methanogenic Archaea (Methanobrevibacter smithii) or other bacteria, like Blautia hydrogenotrophica6.

Several therapeutic approaches

In addition to excluding potentially methanogenic foods (legumes, artichokes, red meat, etc.) from the patient’s diet, activated carbon can absorb the gas in the small intestine. Or, the microbiota can be rebalanced by daily intake of pre- or probiotics7 as a way to prevent gas formation. Lastly, regular physical exercise (30 minutes of walking every day, for example) can also channel this gas production and more progressively eliminate it.


1. Frexinos J et al.1. Etude descriptive des symptômes fonctionnels digestifs dans la population générale française. Gastroenterol Clin Biol 1998;22:785-91.
2. Association Française de FMC en hépato gastroentérologie, ballonnement abdominal quoi de neuf,
3. SFNGE,, les troubles fonctionnels intestinaux,
4. Ford AC, Spiegel BM, Talley NJ, et al. Small intestinal bacterial overgrowth in irritable bowel syndrome. Clin Gastroenterol Hepatol 2009;7:1279-86
5. Ph Ducrotté. Tirés à part: Philippe Ducrotté, ADEN EA 3234
6. Bernalier A, Rochet V, Leclerc M, Dore J, Pochart P. Diversity of H2/CO2-utilizing acetogenic bacteria from feces of nonmethane-producing humans. Curr Microbiol 1996;33:94-9
7. Bergonzelli GE, Blum S, Brüssow H, Corthésy-Theulaz I. Probiotics as a treatment strategy for gastrointestinal diseases? Digestion 2005;72:57-68.

Functional constipation

Functional constipation, a very common digestive disease, particularly among the elderly, is multifactorial. 

Functional constipation is a frequent symptom that can be isolated or part of a functional gastrointestinal disorder (FGD). It affects 5% to 20% of the general population1,2. It can sometimes be very severe and impact the quality of life of those patients3,4.

Multiple factors

Numerous factors can lead to functional constipation: lack of physical exercise, insufficient hydration, inappropriate diet, advanced age, etc. The amount of intestinal methanogenesis (gas production) seems to be associated with slowed transit and, thus, functional constipation5

An unclear pathophysiology

The pathophysiology of functional constipation is multifactorial. More-and-more studies are highlighting intestinal microbiota abnormalities in constipated patients: lower percentages of certain normal bacteria (Lactobacillus, Bifidobacterium and Bacteroides) and higher representation of certain pathogenic bacteria (Pseudomonas aeruginosa, Campylobacter jejuni). This dysbiosis can change intestinal motricity via three mechanisms: release of bacterial endotoxins or molecules during the fermentation process, release of neuroendocrine factors, and modification of the intestinal immune response6.

Multiple therapeutic approaches

In addition to lifestyle and dietary recommendations (sufficient physical exercise, high-fiber diet, etc.), prescribing laxatives is sometimes necessary, avoiding those that further irritate the intestinal mucosa7. Another option is currently developing around probiotics, especially Lactobacillus and Bifidobacterium. Study results showed potentially beneficial effects on intestinal transit and the frequency of bowel movements2,6. The use of synbiotics was also evaluated, and symptoms were attenuated, with patients taking probiotics- and prebiotics- based therapy requiring fewer laxatives8 . However, those results need to be more widely confirmed. 


1. Suares, NC, and Ford, AC (2011). Prevalence of, and risk factors for, chronic idiopathic constipation in the community: systematic review and meta-analysis. Am J Gastroenterol. Année;106;1582-1591.
2. Choi C and Chang S. Alteration of Gut Microbiota and Efficacy of Probiotics in Functional Constipation. J Neurogastroenterol Motil. 2015;21:4-7.
3. Belsey J et al. Systematic review: impact of constipation on quality of life in adults and children. Aliment Pharmacol Ther. 2010;31:938-949.
4. Lacy et al. Bowel disorders. Gastroenterology. 2016;150:1393–1407
5. Attaluri A, Jackson M, Valestin J, Rao SS. Methanogenic flora is associated with altered transit but not stool characteristics in constipation without IBS. Am J Gastroenterol. 2010;105:1407-11. 
6. Zhao Y, Yu YB. Intestinal microbiota and chronic constipation. Springerplus. 2016;5:1130.
7. Prise en charge de la constipation, Société Nationale Française de Gastroentérologie (SNFGE) 2007.
8. Cudmore S, Doolan A, Lacey S, Shanahan F. A randomised, double-blind, placebo-controlled clinical study: the effects of a synbiotic, Lepicol, in adults with chronic, functional constipation. Int J Food Sci Nutr. 2016 Oct 24;volume:1-12. [Epub ahead of print]


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