Optimising Gut Health – A guide to empowering individuals

Gut health is increasingly becoming recognised as not only a wellness trend but the cornerstone of overall well-being, influencing digestion, immunity, mental health, and chronic disease risk. In this blog, we asked dietitian Catherine Rabess to provide a summary of key insights, practical recommendations, and resources from our CPD-endorsed webinar “Optimising Gut Health – Empowering Individuals“, equipping healthcare professionals with evidence-based knowledge and tools to support individuals effectively.

By Catherine Rabess RD BSc Hons

Key messages from the webinar

1. Defining Optimal Gut Health

To understand what is meant by optimal gut health, there needs to be a clear understanding of what is meant by a healthy gut. This definition varies depending on scientific or medical perspective and if a functional viewpoint is taken into consideration. The narrowest definitions focus purely on the absence of a diagnosed disease or disorder. A broader definition might be the absence of disease but also acknowledging a lack of any functional digestive complaints. Van Hul et al. gave an even broader definition of a healthy gut, identifying characteristics of an ideal gut structure and function, including an optimal microbial composition.¹ With a diverse and balanced gut microbiota, where beneficial bacteria thrive, supporting a number of key bodily functions. Put simply, to me a healthy gut is one that is free from disease or functional gut issues with a diverse gut microbiota. This promotes optimal health by its positive influence on other bodily functions.

2. The Role of the Gut Microbiota

The gut microbiota comprises of trillions of microorganisms, including bacteria, fungi, viruses, and archaea, that interact symbiotically with the host. This composition can be influenced by diet, genetics, environment, and antibiotic exposure. Antibiotics, while often necessary or even lifesaving, can significantly reduce microbial diversity.

A well-functioning gut helps in the breakdown and absorption of nutrients while ensuring detoxification and prevention of harmful pathogens taking dominance. Research has shown that individuals with a more diverse microbiome tend to have better metabolic and immune health outcomes, as well as a higher amount of short-chain fatty acids (SCFA)².

SCFA are types of metabolites that are by products of gut microbes fermenting dietary prebiotic fibres and other compounds. These SCFAs such as butyrate, propionate, and acetate are absorbed by human cells and play a crucial role in maintaining the health of the intestinal lining, strengthening the gut barrier, regulating inflammation³ and modulating immune responses⁴.

The gut microbiota plays a crucial role in training and regulating the immune system, this is known as immune modulation. 70% of the immune function resides in the gut. Evidence has shown decreased gut microbial diversity, such as having reduced numbers of Firmicutes (gut bacteria involved in immune regulation and SCFA production) and increased numbers of Proteobacteria, can increase risk of developing autoimmune diseases⁵. Ji et al. study identified an imbalanced microbial environment was associated with Crohn’s disease; immune response and pro-inflammatory activity⁶.

The gut communicates with the brain via the gut-brain axis. Gut microbes communicate with brain chemicals via messengers that affect our appetite, mood and even cognition. These messengers are gut metabolites produced by bacteria-SCFA, neurotransmitters, and their precursors, which can influence and regulate brain function and cognition by impacting nerve signalling and inflammation via the blood circulation^7,8. In addition, the gut microbiota can act on the local nervous system (via the enteric nervous system, the vagus nerve) to quickly transmit signals to the brain^9,10.

Other key functions of the microbiota include:

• Digestion and absorption of nutrients: Certain gut bacteria such as Bacteroidetes assist in breaking down complex carbohydrates, producing essential nutrients like vitamins B and K
• Metabolism: The gut microbes interact with cells that are involved in energy balance and fat storage. Some studies suggest that an imbalance in gut microbiota composition could be associated with conditions like obesity and metabolic syndrome¹¹

3. Gut Dysbiosis and Health Implications

Gut dysbiosis, or microbial imbalance, is associated with various chronic health conditions, including:

Gastrointestinal disorders: IBS, IBD, and functional dyspepsia are linked to alterations in gut microbiota composition. Wang et al. systematic review and meta-analysis identified gut dysbiosis in patients with IBS, identifying lower levels of beneficial strains Lactobacillus and Bifidobacterium¹².

Immune-related conditions: Autoimmune diseases such as rheumatoid arthritis and multiple sclerosis may be influenced by gut microbial imbalances¹³.

4. The Role of Prebiotics, Probiotics, Postbiotics and Synbiotics

Prebiotics:
Prebiotics are non-digestible food ingredients (mainly fibres) that selectively stimulate the growth or activity of beneficial microorganisms, particularly bacteria like Bifidobacterium and Lactobacillus, in the gut. Almonds, okra, dates, prunes, garlic. onions, artichokes, are rich in prebiotics. Here’s how they work:

1. Fermentation by gut bacteria: Prebiotics, such as inulin, fructo-oligosaccharides (FOS), and galacto-oligosaccharides (GOS), reach the colon intact, where beneficial bacteria ferment them.
2. Production of SCFAs: This fermentation produces short-chain fatty acids (SCFAs) like acetate, butyrate, and propionate, which:
   • Improve gut barrier integrity (e.g., butyrate strengthens gut lining)
   • Provide energy for colonocytes, the cells of the colon
   • Regulate local immune responses and anti-inflammatory effects
3. Modulation of the gut microbiota: Prebiotics create a favourable environment for beneficial bacteria, outcompeting harmful pathogens by enhancing beneficial bacterial growth.

Probiotics:

Probiotics are live microorganisms, primarily bacteria and yeast, that when consumed in adequate amounts, confer a health benefit to the host. Their mechanisms include:

1. Colonisation and competition: probiotics adhere to the gut mucosa, competing with harmful pathogens for space and nutrients, reducing the chances of pathogenic bacteria establishing themselves.
2. Strengthening gut barrier function: some probiotic strains (e.g., Lactobacillus, Bifidobacterium) enhance the production of mucins and tight junction proteins, reinforcing the gut’s barrier function.
3. Immune modulation: probiotics interact with gut-associated lymphoid tissue (GALT), stimulating anti-inflammatory cytokines and inhibiting pro-inflammatory responses, balancing the immune system.
4. Production of antimicrobial compounds: probiotics produce substances like lactic acid and bacteriocins that inhibit the growth of pathogenic bacteria.
5. Metabolic benefits: probiotics can improve digestion and absorption of nutrients, promote the production of SCFAs, and reduce gut inflammation.

Together, prebiotics and probiotics work synergistically to promote gut health by balancing the gut microbiota, improving its functionality and contributing to overall digestive health.

• Postbiotics are beneficial compounds known as metabolites that are by products of bacterial fermentation, including SCFAs and peptides.
• Synbiotics are a combination of probiotics and prebiotics that enhance gut microbial function and resilience.

Some strains will have unique properties that may account for certain neurological, immunological, and antimicrobial activities. However, an emerging concept in the field of probiotics is to recognise that some mechanisms of probiotic activity are likely shared among different strains, species, or even genera. Many probiotics may function in a similar e.g., the ability to enhance SCFA production or reduce luminal pH in the colon may be a core benefit expressed by many different probiotic strains. Therefore, some probiotic benefits may be delivered by different strains of certain well-studied species of probiotic strains.

5. The Importance of Fibre and Plant Diversity

Dietary fibre plays a fundamental role in gut health by feeding beneficial microbes and increasing microbial diversity. Gut microbes love plants as they are the only source of dietary fibre. But what are the different types of fibres?

• Cellulose, hemicellulose, pectins, beta-glucans, gums and mucilages, resistant starches and microcomponents.
• Soluble, high fermentable fibre: soak up excess water in the gut. Adding bulk to stools, making it heavier and solid, which can help to slow down transit time. These can be very helpful if suffering with diarrhoea.
• Insoluble, less fermentable fibres: form and soften poo as it does not absorb water/dissolve. It supports regular gut motility and getting things moving. Great if IBS-C or functional constipation.

Fermentable Fibres: absorb water, form gel-like substances.
Gums & Mucilage
📌 Examples: psyllium, chia seeds, xanthan gum
Beta-glucans
📌 Examples: oats, barley, mushrooms
Pectins
📌 Examples: apples, beans, lentils, potatoes

Less Fermentable Fibres: act as bulking agents, do not dissolve
Cellulose
📌 Examples: vegetables, fruits, whole grains, nuts
Hemicellulose
📌 Examples: wheat, bran
Lignans
📌 Examples: seeds, wholegrain cereals

Resistant starches are similar to fibre in that they move through the gut undigested. They are a great prebiotic fibre as the friendly gut bacteria feed off them and ferment producing butyrate – SCFA. It can also help reduce insulin resistance.

6. Fermented Foods and their Role in Gut Health

Fermented foods have been consumed for centuries for their health benefits. However, not all fermented foods contain live cultures. Some of the best sources include:

• Live yoghurt and kefir: these are the most widely consumed, containing beneficial bacteria such as Lactobacillus strains and are supported by the greatest volume of research regarding health outcomes¹⁴. Some yogurts contain additional, specific probiotic strains which have clinical evidence behind them and are proven to survive to the gut.
• Kimchi and sauerkraut: rich in beneficial bacteria but must be unpasteurised to retain live cultures.
• Miso and tempeh: provide beneficial fermentation products, although they may not always contain live microbes.

For more information on fermented foods take a read of the blog – ‘fermented foods – an evidence update’.

7. Addressing Common Myths About Gut Health

“Fibre causes bloating and discomfort”: Gradually increasing fibre intake allows the gut microbiota to adjust and produce adequate amounts of enzymes to support digestion and prevents excessive gas production.

“All probiotics are the same”: probiotic effects are strain-specific and dose dependent. Therefore, selecting evidence-based strains is crucial for targeted health benefits.

“Diet alone determines gut health”: stress, sleep, and physical activity are also critical to maintaining a healthy gut.

Practical recommendations:

1. Increase fibre intake gradually

• UK guidelines from SACN recommend 30g of fibre per day
• Introduce one high-fibre foods every few days to allow the gut to adapt. High fibre foods: flaxseeds (7g/serving), chia seeds (5g/serving), whole grains, pulses, fruits, and vegetables

2. Encourage plant diversity

• Aim for 30+ different plants per week². Focusing on different colours and varieties as these all provide different antioxidant and polyphenol properties
• Include fruits, vegetables, nuts, seeds, wholegrains, legumes, herbs, and spices
• Variety enhances microbial diversity and nutrient synergy (e.g., vitamin C boosts iron absorption)

Find out what counts as plant-points here.

3. Incorporate prebiotic-rich foods daily

• Sources: garlic, onions, leeks, asparagus, bananas, oats, and legumes
• These promote the growth of beneficial gut bacteria, supporting gut health

4. Choose evidence-based probiotics

• Choose products which contain probiotics with strain-specific benefits at clinically effective doses
• Examples:
  • Lactobacillius acidophilus CL1285 and L. casei LBC80R– Supports IBS and reduces prevalence of antibiotic-associated diarrhoea¹⁵
  • Bifidobacterium (animalis) lactis CNCM I-2494– improves constipation and symptoms of minor digestive discomfort¹⁶

5. Encourage regular consumption of fermented foods

• Ensure the product contains live cultures at the time of consumption
• Advise gradually increasing, dependent on tolerance as it could cause bloating

6. Lifestyle strategies for gut health

• Reduce stress: chronic stress alters gut microbial composition
• Exercise regularly: increases microbial diversity and SCFAs
• Improve sleep hygiene: sleep deprivation negatively affects the gut microbiome

7. Addressing cost and accessibility

• Budget-friendly tips:
  • Buy seasonal, frozen, or tinned fruit and vegetables
  • Use legumes and wholegrains to bulk out meals
  • Plan meals and minimise food waste

Resources for Healthcare Professionals

Books:

• The 30 Plan, Catherine Rabess

• Genius Gut, Dr Emily Leeming

• Eat Yourself Healthy, Dr Megan Rossi

• Advanced Nutrition and Dietetics in Gastroenterology, Edited by Dr Miranda Lomer

• Food For Life – Dr Tim Spector

Websites and Tools:

• British Dietetic Association (BDA) – Gut health factsheets

• British Society of Gastroenterology

• World Gastroenterology Organisation (WGO) – Probiotic and Prebiotic guidelines

Conclusion

Supporting gut health requires a holistic, evidence-based approach, integrating diet, lifestyle, and patient education. Promoting plant diversity, fibre intake, and strain-specific targeted probiotics while considering stress, sleep, and physical activity can significantly improve gut health outcomes. By equipping healthcare professionals with up-to-date research and practical strategies, individuals can be empowered to take control of their gut health and overall well-being.

Watch the webinar on demand here.

Disclaimer: This blog has been developed in association with the healthcare professional support team at Activia UK. Approval of each sponsor and activity is carefully assessed for suitability on a case by case basis. Sponsorship does not imply any endorsement of the brand by MyNutriWeb, its organisers, its moderators or any participating healthcare professional, or their association. Sponsorship funds are reinvested into the creation and promotion of professional development opportunities on MyNutriWeb.

References