Daily diarrhoea: what can help?

For ease of reference, figures in brackets refer to the reference numbers appended to this document.

Irritable bowel syndrome (IBS), often referred to as irritable bowel syndrome, can manifest itself in a number of ways. Diarrhea is one of them.

In fact, there are different categories of IBS depending on the symptoms reported (1, 2):

• IBS predominantly constipation (IBS-C): more than 25 % of hard stools and less than 25 % of soft stools
• IBS with predominant diarrhea (IBS-D): more than 25 % of soft stools and less than 25 % of hard stools
• Mixed IBS (IBS-M): more than 25 % of soft stools and more than 25 % of hard stools
• IBS unspecified (IBS-U): less than 25 % of soft stools and less than 25 % of hard stools

Visit SII-D is the most common, affecting around 30 to 40 % of patients (2,3). Since IBS is a disease of exclusion, it is important that the various medical tests (e.g. radiology or endoscopy) have been carried out to rule out other intestinal diseases (2). For example, it's essential that celiac disease, considered a «gluten allergy», has been ruled out. Talk to your doctor!

For more details on all types of IBS, see the blog Irritable bowel syndrome: Beyond FODMAPs, what are the different avenues of intervention?

Potential causes

All the causes of the development of IBS in an individual are still uncertain (2). Several hypotheses refer to alterations in gastrointestinal motility, visceral hypersensitivity, environmental factors, dietary habits and alterations in the microbiota (dysbiosis) (2). Science has yet to establish whether these elements are causes or consequences of the disease (2). The famous chicken-or-the-egg concept?

Potential genetic variations

Various studies have evaluated variation in the sucrase-isomaltase gene as a mechanism involved in IBS, particularly during diarrhea. Sucrase-isomaltase alteration is a condition in which this enzyme, which metabolizes sucrose (a sugar), is deficient. This causes undigested sugars to accumulate in the colon, leading to their fermentation and resulting in the gas formation that contributes to abdominal pain, bloating and osmotic diarrhoea (2). Interesting, isn't it?

The microbiota, its metabolites and diarrhea

As previously mentioned, alterations in the microbiota could be a cause or consequence in the context of IBS. Indeed, several observational studies report differences between certain families of bacteria in people with IBS-D compared to healthy individuals (2). The greatest differences reported involve the Actinobacteriathe Firmicutesthe Bacteroidetes and Proteobacteria (2). Furthermore, IBS is characterized by a disturbance of intestinal integrity (leaky gut) (2).

See the blog post Leaky gut: what you need to know! for more details.

There are thus a number of possible explanations for the link between alterations in certain bacteria and their metabolites, and intestinal symptoms (2).

For example, the bacteria Dorea (in the Firmicutes) has been associated with gas production, abdominal pain and increased intestinal permeability (2). Studies report higher levels of Dorea in subjects with IBS-D compared with healthy subjects (2). It is therefore possible to envisage a potential correlation between IBS-D symptoms and an increase in the abundance of Dorea (2).

Another example involves certain opportunistic bacteria, i.e. bacteria present in the intestine that can become pathogenic. These bacteria, such as Escherichia Coli (E. coli) and Clostridiales could produce a large quantity of toxins leading to the activation of intestinal inflammation responsible for abdominal pain and diarrhoea (2).

To continue, loose stools and diarrhea are also correlated with higher levels of bile acids in the colon (2). Bile acids, excreted into the small intestine via the bile ducts, play a central role in the absorption of dietary fats, and the microbiota is involved in bile acid metabolism (2). A state of dysbiosis (imbalance of the microbiota) alters the physiological functions of bile acids (2). Thus, some IBS-D patients are characterized by malabsorption of bile acids, and their accumulation in the colon causes diarrhea by several mechanisms (2):

• Stimulation of sodium and water secretion
• Induction of mucus secretion
• Increased colonic motility
• Stimulation of defecation and/or damage to the mucosa.

Although several mechanisms remain to be validated and confirmed, it is certain that the microbiota and its metabolites have a role to play in the symptoms of diarrhea.

Nutrition plays an important role in the treatment of these symptoms. In fact, 84% of people with IBS report that the manifestations seem to be related to the food consumed (2).

There are various nutritional recommendations to help manage diarrhea. Let's take a look at some of them.

Basic recommendations

Various recommendations are mentioned by organizations such as the National Institute for Health and Care Excellence (NICE) to help manage the symptoms of diarrhea. (2)

• Eat regular meals in moderate portions and avoid skipping meals.
• Eat slowly
  Aim for 2L of water a day
• Moderate fat intake (e.g. nuts, seeds, avocado, fatty fish, oils) and limiting consumption of foods rich in added fats (e.g. fried foods, breadcrumbs, fatty sauces, processed foods, fast food).
• Limit consumption of spicy foods, alcohol, caffeine, sweeteners («false sugars», e.g. saccharin and sucralose), sugar alcohols (e.g. sorbitol) and fructose.

These latter foods are considered transit «stimulants». For example, coffee can increase intestinal motility and reduce intestinal transit time, i.e. the time it takes for food to reach the rectum from the stomach.

→ Encourage consumption of foods rich in soluble fibers (e.g. oats, oat bran, psyllium, quinoa, sweet potato, chia seeds) and limit consumption of foods rich in insoluble fibre (e.g. whole wheat).

Soluble fibers should be favored in the context of diarrhea, as they have the ability to form a gel and make stools more «compact» and shaped (2).

Calculate your daily fibre intake: this tool is for you!

→ Validate lactose tolerance

L'lactose intolerance can be a cause of diarrhea. Undigested lactose reaches the colon intact and is fermented by the intestinal microbiota, causing abdominal distension and symptoms such as diarrhea, swelling and abdominal pain (2). The prevalence of lactose intolerance appears to be significantly higher in subjects with IBS-D than in healthy individuals, although it is not always associated with malabsorption (2).

FODMAPs

Yes, the low-FODMAP diet has been shown to reduce gastrointestinal symptoms, including diarrhea (2).

For more details on this diet, see the blog Irritable bowel syndrome: Beyond FODMAPs, what are the different avenues of intervention?

However, it is essential to remember that this food must be temporary since it is highly restrictive and limiting. The low FODMAP diet also has a potential negative impact on the microbiota by reducing intakes of prebiotic foods! A nutrition reference is essential to support this approach!

You want reliable information about FODMAP: here's the guide you need!

To remember

There is no one-size-fits-all nutritional recommendation for managing the symptoms of diarrhea. A personalized approach based on your symptoms, past experiences and health conditions is essential. It's essential to maintain optimal gut microbiota health!

Make an appointment with a dietitian-nutritionist from the Épithélia team!

You are more self-taught: this course may be of interest to you.