Is Leaky Gut Real?

The term ‘leaky gut’ in recent years has gained immense popularity and become a buzzword. Although there was some doubt of whether something like this existed in the past, more and more research is finding that it is real phenomenon that is present in several chronic diseases. It has even been proposed as the underlying cause for many medical conditions including IBS. But, whether or not leaky gut plays a key role in causing these medical conditions is still unknown and scientific research does not yet have a clear answer in support of this idea.

Before you start thinking you have a giant hole in your gut lining, leaky gut is just a scary term used to describe that you have increased intestinal permeability.

What is ‘leaky gut’?

In scientific terms, ‘leaky gut’ refers to intestinal barrier dysfunction. It is an inflammatory state of the gut where there is an increased intestinal permeability in which the gut lining is compromised and becomes “leaky”, allowing inflammatory substances like harmful toxins, microbes and any other nasties that can make us sick out of the gut into the bloodstream. In a healthy gut, the intestines are resistant to the entry of harmful substances into blood circulation.

Understanding the Intestinal Barrier Dysfunction

Our gut (small and large intestines) is lined by a chain of epithelial cells held together by what is called as tight junctions. This cell lining also sometimes referred to as the gut lining along with its tight junctions forms a protective barrier that is tightly regulated to separate the contents of the gut from the bloodstream.

Under normal, healthy circumstances, the cells lining the gut are held together by these tiny tight junction gaps selectively allowing nutrients into to the bloodstream and secreting waste while keeping potentially harmful substances out. The intestinal barrier is selectively permeable that tightly controls what gets absorbed in the bloodstream. Think of it like a tea bag – where the gaps in the fabric of the tea bag locks the tea leaves inside of the bag while only releasing the flavour.

When our intestines become irritated or inflamed, these tight junctions loosen. This increases the permeability of the intestinal lining resulting in the dysfunction of intestinal barrier.

Intestinal Barrier Dysfunction refers to the disruption of the intestinal barrier, where this gate-keeping mechanism is faulty thereby allowing undesirable, nasty and toxic substances including partially digested food, toxins, and microbes to penetrate the tissues beneath it and enter the bloodstream thus, the term leaky. This can lead to an inflammatory response from the immune system that gets alarmed with unwarranted substances entering the tissues and circulatory system. Hence, the negative effects of this barrier dysfunction can sometimes

extend beyond the gut. Intestinal barrier dysfunction is also known to accompany microbial dysbiosis in the gut adding more fuel to the fire…. more inflammation.

Leaky Gut and IBS

You might have often heard a mention of “Leaky gut” in association with IBS but, whether alterations in the gut barrier function are a part of the cause of IBS is still debated (1, 2). There are only small number of studies that investigated intestinal barrier dysfunction in IBS patients with most focussing on those with IBS-D (i.e. IBS with diarrhoea predominant symptoms). While some studies reported no significant differences in intestinal permeability of IBS patients compared to healthy people, others have found relatively increased permeability in small and large intestines of IBS patients. Moreover, the current methods of measuring or diagnosing intestinal barrier dysfunction are unsatisfactory and not very reliable adding more complexity in interpreting the results.

Thus, currently there is no clear-cut evidence that support that defect in gut barrier is an underlying cause of IBS and more research is needed to understand this better.

What causes Intestinal Barrier Dysfunction?

There are range of factors that can injure the gut lining thus increasing the intestinal permeability and cause intestinal barrier dysfunction.

Inflammatory diet: A diet high in refined sugar, saturated fats, animal proteins and processed foods that is low in plant foods and dietary fibre/prebiotics can all add to inflammation of the gut lining (5).

Alcohol: Alcohol also induces inflammation throughout the gut, altering the composition and function of the microbiome and increasing gut permeability. Increased gut permeability is also linked to increased risk of liver disease (3).

Medication: While antibiotics can kill bacteria that makes us sick, they also kill good ones causing dysbiosis (disturbance of balance between good and bad microbiota). Microbial dysbiosis is associated with barrier dysfunction. Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen can also really irritate the intestinal lining and damage protective mucus layers (4).

Stress: Acute and chronic psychological stress can increase gut permeability in humans. Stress leads to spike in our cortisol levels that makes gut junctions larger. This negatively impacts the immune system, triggering inflammation and disturbing the microbiome.

Acute and Chronic conditions: Diseases and Infections (e.g. coeliac disease, inflammatory bowel diseases, cancer etc) can trigger inflammation and disturbances in microbiome in the gut. Also, low-grade chronic inflammation is also linked to increased permeability and microbial dysbiosis in the gut.

Restoring a healthy gut lining

Restoring and maintaining a healthy gut lining involves keeping your gut microbiota balanced and this balance could be achieved by a combination of lifestyle, dietary and supplement interventions.

  • Increase intake of fibre-rich plant foods e.g. fruit, vegetables, wholegrains, nuts, seeds and legumes
  • Include prebiotic dietary fibre and probiotics in your diet
  • Limit consumption of highly processed foods that are high in fats and sugar
  • Avoid alcohol
  • Get enough sleep & rest
  • Increase exercise and physical activity
  • Connect socially and include strategies to manage stress levels

The Bottom line:

Leaky gut is nothing but intestinal barrier dysfunction where increased gut permeability allows bacteria and toxins to pass through the intestinal wall into the bloodstream leading to inflammation. While there is plenty of evidence to prove that increased intestinal permeability is present in number of chronic diseases and it is involved in the pathogenesis of several chronic conditions, overall, there is not yet conclusive evidence that increased gut permeability is the underlying cause of chronic diseases.

By Dr Tanvi Shinde, PhD

References:

  1. Martínez, C.; González-Castro, A.; Vicario, M.; Santos, J. Cellular and Molecular Basis of Intestinal Barrier Dysfunction in the Irritable Bowel Syndrome. Gut Liver 2012, 6, 305–315, doi:10.5009/gnl.2012.6.3.305
  2. Matricon, J.; Meleine, M.; Gelot, A.; Piche, T.; Dapoigny, M.; Muller, E.; Ardid, D. Review Article: Associations between Immune Activation, Intestinal Permeability and the Irritable Bowel Syndrome.
  3. Alimentary Pharmacology & Therapeutics 2012, 36, 1009–1031, doi:10.1111/apt.12080
  4. Bishehsari, F.; Magno, E.; Swanson, G.; Desai, V.; Voigt, R.M.; Forsyth, C.B.; Keshavarzian, A. Alcohol and Gut-Derived Inflammation. Alcohol Res 2017, 38, 163–171.
  5. Sigthorsson, G.; Tibble, J.; Hayllar, J.; Menzies, I.; Macpherson, A.; Moots, R.; Scott, D.; Gumpel, M.; Bjarnason, I. Intestinal Permeability and Inflammation in Patients on NSAIDs. Gut 1998, 43, 506–511, doi:10.1136/gut.43.4.506
  6. Makki K, Deehan EC, Walter J, Bäckhed F. The Impact of Dietary Fiber on Gut Microbiota in Host Health and Disease. Cell Host Microbe. 2018 Jun 13;23(6):705-715. doi: 10.1016/j.chom.2018.05.012. PMID: 29902436