Why gut health and the role of the gut microbiota should not be underestimated in the care of patients

By Rachel Redman - Registered Dietitian 

 Gut health is an integral component of overall human health and wellbeing, with the 100 trillion+ microbes that colonise our digestive tract and populate the microbiota playing a key role in protecting us against disease.¹ In fact, over 2400 years ago, Hippocrates, the legendary Green physician, reportedly stated: “All disease begins in the gut”.² Even today, the importance of gut health should not be underestimated in providing comprehensive care for patients.

The microbial population in the colon has been the focus of recent scientific and clinical developments. The colon has the highest concentration of gut microbes and is home to up to 100 billion microbes per gram.³ The significance of the colon is reflected in NICE's recent recommendation of Faecal Microbial Transplantation (FMT) for recurrent Clostridium difficile infection (CDI)⁴, offering a reported cure rate >90%.⁵

The role of the gut microbiome

The role of the gut microbiome in gastrointestinal health is mediated by:

• Fermentation in non-digestible carbohydrates to produce short chain fatty acids, which have both local and systemic effects.
• Nutrient synthesis by-products like B vitamins, Vitamin K and amino acids.
• Development and maturation of the gut’s own immune system.
• Modulation of inflammation via production of inflammatory mediators.
• Maintenance of gut barrier function and integrity, protecting the host from invading pathogens.

The gut microbiome plays a major role in keeping the gut barrier functioning properly, acting as a first line of defence against potentially dangerous pathogens and food antigens.⁶ For example, the gut can be protected from pathogenic microbes by forming a physical barrier, known as “colonisation resistance”. The gut barrier function is further enhanced through the production of antimicrobial substances that inhibit pathogen growth, bioactive metabolites that feed and maintain a healthy intestinal mucosa, and stimulation of mucous secretion from goblet cells to reduce bacterial translocation.

Evidence has demonstrated an association between increased intestinal permeability and systemic chronic inflammatory disorders.⁶ Dysbiosis and a dysfunctional gut barrier have been associated with many metabolic and auto-immune conditions such as obesity, type 2 diabetes, and inflammatory bowel disease.⁷

Practical tips to help improve your patients gut health

Numerous factors have been identified to affect the development, maturation, diversity and richness of our gut microbiome, including the manner of childbirth, method of infant feeding, age, intestinal infections and even the people and pets we live with. Despite these elements being difficult to alter retrospectively, lifestyle choices and environmental factors are more readily adjustable to optimize our gut health.

For instance:

• Diet: the foremost factor that influences our gut microbiome is diet; a typical Western-style diet that is high in processed foods, refined carbohydrates and saturated fats has been found to detrimentally modify the balance of bacteria in our guts. This may increase the likelihood of developing myriad inflammatory, metabolic and auto-immune disorders.⁸ In contrast, a nutrient-dense, high-fibre diet that contains whole plant foods as well as non-digestible fermentable carbohydrates can bolster bacterial diversity and richness – thus producing beneficial metabolites which ultimately boost overall health. Moreover, appropriate probiotic supplementation could provide further support for improving microbial composition in humans with an illness or disorder.⁹
• Medication: antibiotics and laxatives can decrease microbial species necessary for gut homeostasis, while proton pump inhibitors (PPIs), Metformin, and selective serotonin re-uptake inhibitors (SSRIs) can interact with the gut microbiome in a complex manner.¹⁰ Studies have even demonstrated that PPIs decrease colonisation resistance and increase risk of enteric infections – including Clostridium Difficile, but recent research has suggested that probiotic intervention can counteract some of these changes.¹¹
• Physical activity: Physical activity has also been correlated with alterations to the gut microbiota; studies demonstrate that exercise encourages growth of Lactobacillus and Bifidobacterium genera while augmenting production of short-chain fatty acids (SCFAs).^12-13
• Sleep: sleep quality and quantity may be associated with increased microbial diversity within the digestive tract; circadian rhythms appear to sync up with those of our gut microbes.¹⁴
• Stress: chronic stress can elevate risk for developing leaky gut due to its ability to raise intestinal permeability. This increases the risk of bacterial translocation and associated inflammation.¹⁵
• Alcohol: excessive alcohol consumption has been linked with decreased microbial colonies in the gut as well as nutritional deficiencies – including SCFAs - caused by alterations to the gut microbiome and impaired epithelial integrity.¹⁶

Overall, probiotics should not be underestimated when it comes to patient care. Probiotics provide numerous benefits which can impact health and disease and improve overall health and wellbeing. Furthermore, probiotic supplements are easy to access, making them a great addition to any healthcare professional's toolkit for promoting optimal gut health for their patients.

References: 

1. Lyon L. Brain 2018 141; 1–5 | e20. https://pubmed.ncbi.nlm.nih.gov/29444202/ 
2. Hills RD et al Nutrients. 2019 Jul; 11(7): 1613. https://www.mdpi.com/2072-6643/11/7/1613 
3. De Vos WM et al Gut 2022;71:1020–1032. https://pubmed.ncbi.nlm.nih.gov/35105664/
4. NICE Medical Technologies Guidance MTG71 2022 Evidence-based recommendations on faecal microbiota transplant for recurrent Clostridioides difficile infection. 
5. Quraishi NM. et al 2017. Aliment Pharmacol Ther 2017 Sep;46(5):479-493. https://onlinelibrary.wiley.com/doi/10.1111/apt.14201
6. Kocot AM et al. Int J Mol Sci 2022 Mar 7;23(5):2896. https://pubmed.ncbi.nlm.nih.gov/35270039/
7. Allam-Ndoul B et al Int J Mol Sci 2020 Sep 3;21(17):6402. https://pubmed.ncbi.nlm.nih.gov/32899147/

8.Malesza IJ et al Cells. 2021 Nov; 10(11): 3164. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8619527/ 

9. Cancello R et al. Nutrients 2019, 11, 3011; https://www.mdpi.com/2072-6643/11/12/3011 

10. Weersma RK et al. Gut 2020 Aug;69(8):1510-1519 https://pubmed.ncbi.nlm.nih.gov/32409589/
11. Singh G et al. Clinical Nutrition ESPEN 47 (2022) 70-77 https://clinicalnutritionespen.com/article/S2405-4577(21)01109-8/fulltext

12.Mailing LG et al. Exerc Sport Sci Rev 2019 Apr;47(2):75-85. https://pubmed.ncbi.nlm.nih.gov/30883471/  

13. Dalton A et al. Gut Microbes 2019;10(5):555-568 https://pubmed.ncbi.nlm.nih.gov/30704343/
14. Smith RP et al PLoS One 2019 Oct 7;14(10):e0222394 https://pubmed.ncbi.nlm.nih.gov/31589627/
15. Mörkl et al.  Curr Nutr Rep 2020 Sep;9(3):171-182 https://pubmed.ncbi.nlm.nih.gov/32406013/
16. Phol K. et al Nutrients 2021 Sep 11;13(9):3170. https://pubmed.ncbi.nlm.nih.gov/34579046/