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The intestinal barrier

The intestinal barrier stops unwanted molecules or bacteria entering the body

The whole of the intestine is lined by a single layer of cells called the intestinal epithelium. However, there are narrow gaps between neighboring cells in the epithelium. These gaps are normally sealed by complex protein networks called ‘tight junctions’ that help maintaining a barrier between the contents of the intestines and the rest of the body.1-4

However, the tight junctions may not always perfectly seal the gaps between epithelial cells. In this case, unwanted molecules, or bacteria that cause inflammation could pass through the gaps, therefore escaping from the gut and entering the rest of your body.5,6 This may be referred to as a ‘leaky gut’.7

Sometimes the intestinal barrier does not function as it should

If the intestinal barrier is not functioning properly, the result may be intestinal inflammation.8 This has been associated with conditions such as celiac disease, Crohn’s disease, and irritable bowel syndrome.9 However, because inflammatory molecules may reach other organs via the blood, long-term dysfunction of the intestinal barrier can play a role in other conditions around the body including autoimmune, metabolic, and cardiovascular diseases,6,10-13 and has recently also been associated with psychological and psychiatric disorders.14-17

What role do dietary and lifestyle factors play?

Dietary and lifestyle factors influence the function of tight junctions and how easily molecules can pass through. For example, the following can affect how well the tight junctions work:

  • A diet rich in fats impairs the tight junction structure6,13,18
  • A diet rich in fiber can protect the tight junctions by stimulating the production of beneficial molecules by the healthy bacteria in the gut6,13,18
  • Chronic alcohol intake can increase the passage of inflammatory molecules through the intestinal barrier and into the bloodstream6,19,20
  • Certain stressful stimuli may also lead to the tight junctions not working properly6,21
  • Some probiotics may help support healthy tight junctions and make them less vulnerable to damage from lifestyle and other factors22,23
Numerous laboratory studies have shown how the probiotic Lactobacillus rhamnosus, LGG® has positive effects on the intestinal barrier through stabilization of tight junctions.24-30 LGG® has been shown to provide benefits across many health areas in different age groups and the positive effects on tight junctions and the intestinal barrier may be a reason for some of these clinical effects.31-33

LGG® is a registered trademark of Chr. Hansen A/S.

The article is provided for informational purposes regarding probiotics and is not meant to suggest that any substance referenced in the article is intended to diagnose, cure, mitigate, treat, or prevent any disease.

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Reference list

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  2. Zihni C, et al. Tight junctions: From simple barriers to multifunctional molecular gates. Nat Rev Mol Cell Biol. 2016;17(9):564–580. (PubMed)
  3. Capaldo CT, et al. Layered defense: how mucus and tight junctions seal the intestinal barrier. J Mol Med. 2017;95(9):927–934. (PubMed)
  4. Rowart P, et al. Implications of AMPK in the formation of epithelial tight junctions. Int J Mol Sci. 2018; 19(7):2040. (PubMed)
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