What is the gut barrier?

The gut barrier is a mucosal surface that functions as a physical and immunological defence barrier. A healthy gut barrier allows essential nutrients to be absorbed while keeping pathogenic microorganisms and food antigens out. In contrast, intestinal barrier dysfunction is associated with various gastrointestinal disorders.

The intestinal mucosa is composed of several elements. The mucus layer of the gut barrier overlays the intestinal epithelium. The commensal gut microbiota occupies this layer, and antimicrobial proteins and secretory immunoglobulin A (SIgA) molecules are secreted into it as immune-sensing and regulatory proteins. The intestinal epithelial cells form a continuous layer that are tightly attached to one another by junctional complexes (e.g. tight junctions, adherens junctions and desmosomes). Beneath this layer is the lamina propria that contains immune cells (e.g. T cells, B cells, macrophages, and dendritic cells) from the innate and adaptive immune system¹ (see Figure 1).

Figure 1. Components of the gut barrier¹

Abbreviations: adherens junction (AJ), antimicrobial proteins (AMPs), intestinal epithelial cells (IECs), secretory immunoglobulin A (SIgA), tight junction (TJ)

What symptoms are associated with compromised gut barrier function?

- Acid reflux/heartburn

- Indigestion/dyspepsia

- Nausea and vomiting

- Belching and regurgitation

- Upper abdominal fullness and pain

- Abdominal bloating

- Abdominal cramps and spasms

- Flatulence

- Changes in bowel habits, diarrhoea or constipation

- Food sensitivities

How can nutrients and herbs improve gut barrier function?

Glutamine is an important fuel source for enterocytes and immune cells, and supports intestinal mucosal integrity.²

Vitamin A and its derivatives regulate the growth and differentiation of intestinal cells.³

Zinc maintains the epithelial barrier. It has been shown to selectively modify tight junctions and therefore alter gut barrier function.⁴

Vitamin D plays a significant role in the maintenance of gut barrier integrity, surveillance of the gut microbiota and inflammatory immune responses.⁵ It is involved in preserving the integrity of junctional complexes and the healing capacity of colonic epithelial tissue.⁶

Curcuma longa (Turmeric) contains curcumin – a potent anti-inflammatory agent.⁷ The major site of action of curcumin is thought to be the intestinal barrier.⁸ Accordingly, curcumin can help improve intestinal barrier function, and potentially clinical outcomes, in intestinal inflammatory diseases.⁹

Brassica oleracea var. italica (Broccoli) contains a phytochemical called sulforaphane which,¹⁰ like curcumin in Turmeric,⁹ induces phase II liver detoxification enzymes. Both nutrients have also been shown to modulate the composition and diversity of the gastrointestinal microbiota,^11,12 and have been reported to protect the gastric mucosa against oxidative injury.^13,14

Glycyrrhiza glabra (Licorice) is traditionally used as a demulcent to soothe irritated tissues. It promotes the healing of ulcers by acting on the gastric mucosa.¹⁵

Actinidia deliciosa (Kiwifruit)¹⁶ and Larch^17,18 are both sources of dietary fibre that exert a prebiotic effect, supporting the growth of beneficial gut bacteria.

Aloe vera (Aloe Vera) has anti-inflammatory and wound healing properties.¹⁹

Apple provides a natural source of prebiotic pectin. Pectin can support the intestinal immune barrier as it interacts with both the intestinal microbiota and intestinal immune cells.²⁰

Taken together, these nutrients help to maintain the structure, function and integrity of the gut barrier.

What is ResistAid®?

ResistAid® is a sustainable Larch polysaccharide (arabinogalactan) supplement that provides immune support to both innate and adaptive immune responses.²¹

What is GutGard®?

Licorice supplements are commonly deglycyrrhized to avoid adverse side effects such as reduced potassium and high blood pressure, which occur when ingested in high amounts. GutGard® is a flavonoid-rich bioactive extract that goes beyond degycyrrhizination. Conventional deglycyrrhizinated Licorice (DGL) extracts lack the flavonoids found in the root, whereas GutGard® uses a unique extraction process that removes glycyrrhizin but retrieves the bioactive flavonoid profile. It is standardised to contain 10% total flavonoids with <0.5% glycyrrhizin.²²

Double-blind, randomised, placebo-controlled studies shown that GutGard® is beneficial in functional dyspepsia²³ and Helicobacter pylori infection.²⁴

What is Digesten®?

Digesten® Kiwifruit complex is a freeze-dried powder containing high levels of Kiwifruit’s protease enzyme (actinidin) which can work at stomach acid pH to support protein digestion. It is also enriched with Kiwifruit polyphenols and soluble fibre (prebiotics) that promote a healthy gut microbiota.²⁵

What is BroccoPhane®?

BroccoPhane® is a Broccoli sprout powder rich in sulforaphane – a powerful antioxidant phytochemical and inducer of phase II liver detoxification enzymes. These enzymes help to neutralise free radicals and reinforce the body’s natural protective responses to oxidative stress. It is standardised to >4000 ppm sulforaphane.²⁶

When might gut healing herbs and nutrients be prescribed?

- Functional dyspepsia^23,27

- H. pylori infection and gastric mucosal damage^24,28,29

- IBD:³⁰ ulcerative colitis^31-35 and Crohn’s disease³⁶

- Non-steroidal anti-inflammatory drugs (NSAIDs)-induced intestinal
  permeability³⁷

- Coeliac disease^38-40

- Irritable bowel syndrome (IBS),⁴¹ including post-infectious, diarrhoea-   
  predominant IBS (IBS-D)⁴²

- Functional constipation⁴³

- For microbiota modulation where a prebiotic effect is desirable to improve
  composition^16,44,45

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21. Lonza. ResistAid® arabinogalactan [Internet]. Norwest: Lonza; 2023 [cited 2023 Sep 13]. Available from: https://www.capsugel.com/consumer-health-nutrition-products/resistaid-arabinogalactan

22. Natural Remedies. GutGard® [Internet]. Bangalore: Natural Remedies; 2023 [cited 2023 Sep 13]. Available from: https://naturalremedieshumanhealth.com/gutgard/

23. Raveendra KR, Jayachandra, Srinivasa V, Sushma KR, Allan JJ, Goudar KS, et al. An extract of glycyrrhiza glabra (GutGard) alleviates symptoms of functional dyspepsia: a randomized, double-blind, placebo-controlled study. Evid Based Complement Alternat Med. 2012;2012:216970. DOI: 10.1155/2012/216970

24. Puram S, Suh HC, Kim SU, Bethapudi B, Joseph JA, Agarwal A, et al. Effect of GutGard in the management of Helicobacter pylori: a randomized double blind placebo controlled study. Evid Based Complement Alternat Med. 2013;2013:263805. DOI: 10.1155/2013/263805

25. NZ Extracts. Digesten® kiwifruit digestive complex - the New Zealand difference [Internet]. Riverlands: NZ Extracts; 2013 [cited 2023 Sep 13]. Available from: https://www.nutraingredients.com/Product-innovations/Digesten-R-Kiwifruit-Complex-The-New-Zealand-Difference

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 [SW1]Please change the title as this implies a direct link to a product, especially as you are calling out the trademarked ingredients