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Foundations of health part one: probiotics

More than 2000 years ago, Hippocrates suggested that all disease begins in the gut, and modern medicine continues to demonstrate that, very often, this is indeed the case. The gut has many functions central to health including digestion, absorption, immunity, detoxification and elimination. However, many factors of modern living such as stress, poor diet, excess alcohol, illness and antibiotic use, can adversely affect gut health.

Probiotics are live microorganisms that help to keep the digestive system healthy by ameliorating the growth of harmful gut microbes and boosting the number and diversity of beneficial gut microbes. An imbalance of gut microflora may play a key role in the development of some gastrointestinal symptoms and disorders.

Replenishing gut microflora with a multi-strain probiotic supplement offers a simple and effective way to support the gut, and therefore overall health and wellbeing.

Despite the remarkable complexity of the gut, there is a growing awareness and understanding that the health of our gut is central to our overall health.

Irrespective of this, many of us have poor gut health and digestive disorders account for more than 10% of the work of GPs.1

As will be discussed further on, the gut is intrinsically linked to all aspects of health and so should become an important focus when addressing our well-being.

There are approximately 100 trillion microbes in the gut, which are often referred to as the gut flora, gut microflora, or the gut microbiome. The gut is a complex ecosystem where our gut flora, nutrients, and own cells should interact as a symbiotic partnership; we provide nutrients for the microbes that inhabit our gut and, in return, they help us maintain a healthy gut.

In many of us, however, this partnership has broken down and can become detrimental to our health. Gut flora can be categorised into different groups – beneficial or commensal; pathogenic; or benign. The microbiome is now best thought of as a virtual organ of the body.2 

Functions of the gut microflora

The functions of our gut flora include assisting digestion, vitamin production, providing structural integrity to the gut mucosal barrier, protection against pathogens, and serving as a communication centre.

The gut flora, hence, play a pivotal role in the regulation of metabolic, immune, and endocrine functions. Consequently, imbalances can have wide-reaching affects.

Skip to Key Takeaways

Dysbiosis and leaky gut

An imbalanced gut flora is often referred to as ‘dysbiosis’ and can lead to many gut-specific symptoms. It is also associated with a condition called ‘leaky gut’, and hence many symptoms beyond the gut.

When the contents of the gut “leak” into the body, the immune system is activated, creating inflammatory mediators that travel throughout the body and cause systemic inflammation, potentially affecting any body tissue. This is why research continues to find associations between the impairment of our gut flora, and many health conditions.

In fact, extensive studies have shown connections between the health of the gut and chronic disease, immune system function, mental health conditions, autoimmune diseases, skin conditions, and more. An unhealthy gut can also impair the body’s ability to absorb nutrients and regulate blood sugar. 

What factors can affect the development of our gut microflora?

There are many factors that can affect the development of our gut flora. These include prenatal factors such as the gut flora of the mother; neonatal factors such as the type of delivery (vaginal/c-section) and antibiotic administration; and postnatal factors, which may include type of feeding (bottle/breast), antibiotic use, maternal diet, environment, weaning, and so on.

Fast forward to childhood/adulthood and there are a host of other factors that can disturb the ratio of good-to-bad bacteria, including food choices, stress, poor sleep, pollution, disease, medications, antibiotics, the list goes on. 

Gut microflora, diet and lifestyle

Currently, approximately half of the adult population are taking prescription medications,3 with estimates from Age UK showing that nearly two million people over 65 are likely to be taking at least seven. Furthermore, 15 million of us in the UK are now living with a chronic disease.4 Factor in our heavy reliance on processed foods, high levels of chronic stress and an increasingly polluted environment, and we have an incredible number of us living with poor gut health.

Food Choices – a recent systematic review concluded that nutrition has profound effects on microbial composition, in turn affecting wide-ranging metabolic, hormonal, and neurological processes.6 Perhaps of most importance, therefore, is our shift in food choices over the last decades, which has seen a rise in the ‘Western’ style way of eating, typically defined as one that is nutrient poor and calorie dense.

The Westernised diet is also characterised by a low intake of fibre. Dietary fibre promotes beneficial bacteria, which ferment soluble fibre into short-chain fatty acids (SCFAs). SCFAs exert many important roles, including providing an energy source for human colonocytes, and having beneficial effects on glucose and energy homeostasis.2

SCFAs also have anti-inflammatory effects and help to heal the tight junctions between cells and thus protect the integrity of the gut barrier.

On average we are only eating around 12-18g of fibre per day, although the government recommends at least 30g.

Further to this, a recent analysis of the UK’s major dietary surveys show that fruit and vegetable intake is suboptimal in all groups of the population.

Fruit and vegetable intake is positively associated with gut microbiota diversity and composition. Moreover, many of us are now consuming processed and convenience foods every day and over two thirds of young adults consume takeaways once per week or more.6 Processed foods have become a major hallmark of the Western diet and are associated with “bad” gut microbes.

Medications – a range of medications can have a detrimental effect on the microbiome. Antibiotics have broad spectrum of action that impacts on healthy microbes, in addition to the harmful bacteria. This negatively affects the composition of the gut microbiota, disturbing metabolism, and the absorption of nutrients.

The overuse or misuse of antibiotics has led to widespread imbalances of native beneficial probiotic species in our intestines. The number of antibiotic prescriptions made in general practice between April and August in 2020, was over 10 million.7

Proton pump inhibitors (PPIs) are a group of medicines known by names such as lansoprazole and omeprazole and work by reducing the production of acid in the stomach. They are widely prescribed for gastric ulcers, gastro-oesophageal reflux disease (GERD) and for the treatment of Helicobacter pylori.

PPIs are some of the most commonly prescribed drugs, with nearly 60 million prescriptions dispensed annually in the UK alone.8 Long-term PPI administration has been shown to alter intestinal bacterial population by suppressing the gastric acid barrier9 and has been associated with small intestinal bacterial overgrowth (SIBO).

Stress – can reshape the gut bacteria’s composition through stress hormones, inflammation, and autonomic alterations.10 Diet also functions as a major pathway from stress to gut dysbiosis as mild stressors can encourage unhealthy eating. This is concerning as a recent UK-survey states that overwhelming majority (79%) of UK adults feel stressed at least one day a month.11

Sleep – stress can also contribute to poor sleep. Inadequate sleep (i.e., duration and/or quality) is becoming increasingly recognised as a global public health issue12 and there is considerable evidence showing that poor sleep can alter the gut microbiome equilibrium.

Studies show that circadian clock misalignment and sleep deprivation changes circadian clock gene expression and microbial community structure.13 A recent study has demonstrated that the average person living in the UK only sleeps between 5.78 and 6.83 hours per night, less than the recommended 7-8 hours.14

Environment – humans now have chronic exposure to a wide range of environmental assaults, including heavy metals, chemicals, and pollution etc. Pesticides have been shown to negatively alter the gut microbiota composition, gut barrier, and induce dysbiosis, resulting in multiple potential adverse effects. Further to this, evidence shows that heavy metals may contribute to the progression of various diseases and that the aetiology and progression of these diseases is partly due to heavy metal induced perturbations of the gut microbiota.15 

How can an unbalanced gut flora present itself?

There are many ways an unbalanced gut flora can present itself and some potential warning signs to look out for include:

Disturbances specific to the gut – gas, bloating, constipation, or diarrhoea may be a good indication that our balance is out. This is often because low levels of beneficial bacteria may result in difficulty processing food and eliminating waste.

Craving sugareating excessive sugar can starve out beneficial bacteria and cause pathogenic bacteria and yeasts to thrive. As these then require more sugar to feed on our cravings can increase.

Weight gainan imbalanced gut can weaken the body’s ability to control blood sugar and absorb nutrients. Weight gain may therefore be triggered by insulin resistance or the desire to eat in excess due to reduced nutrient absorption.

Food sensitivities – a leaky gut is associated with allergies and food sensitivities. Food sensitivities also create a vicious cycle in that they help maintain the reason for their development (leaky gut) while often being the direct cause of the various symptoms suffered.17

Yeast Overgrowth – A diet high in sugar, refined carbohydrates, and processed foods makes it easy for yeast to multiply and thrive. Too much yeast in relation to good bacteria can overpower the bacteria, leading to digestive issues and fungal infections.

Fatigue – a lack of diversity in the gut has been linked with low energy and chronic fatigue. Serotonin, a hormone that affects sleep and mood is produced in the gut.

Skin reactions – skin flare ups have been linked to inflammation in the gut caused by a lack of good bacteria.

Mood Problems – anxiety, depression, and mood swings are associated with the health of the gut. The presence of good bacteria in the gut supports the production and regulation of mood-related chemicals such as dopamine and serotonin.

How do probiotics help the gut?

As there are close links between our microbiome, health, and disease, there is a growing interest in supplementing with “probiotics.” Probiotics are live micro-organisms, commonly referred to as ‘friendly’ bacteria, and help to support a healthy balance of bacteria in the gut.

They act as a barrier against harmful bacteria that pass through the gut, helping to ensure they don’t take up residence.

In reality, our diet and lifestyles have now become so detrimental to our gut flora that most of us would benefit from giving it some extra support by introducing probiotic foods, or by supplementing with a good quality probiotic.

Probiotics can contain a range of microorganisms – the most common belonging to the groups Lactobacillus and Bifidobacterium. Yeasts may also be used such as Saccharomyces boulardii.

The key probiotic mechanisms of action include:

  • Enhancement of the epithelial barrier
  • Increased adhesion to intestinal mucosa
  • Concomitant inhibition of pathogen adhesion
  • Competitive exclusion of pathogenic microorganisms
  • Production of anti-microorganism substances
  • Modulation of the immune system

There is an abundance of evidence linking probiotic use with helping a wide range of conditions and complaints.

Sleep – interaction via the gut-brain axis suggests that modification of the gut microbial environment via supplementation with probiotics may improve sleep health. A systematic review and meta-analysis carried out last year showed that probiotics significantly increased sleep quality. 12-14

Mood – a systematic review of human studies found that supplementing with bifidobacterium and lactobacillus strains for 1-2 months improved anxiety, depression, and memory.17 A recent literature review stated that probiotics or prebiotics may decrease the severity of these mental disorders (depression and anxiety) by altering the gut microbiota.18

Skin conditions – the skin possess its own microbiome which is heavily influenced by the gut flora. Studies have demonstrated that probiotics can exert beneficial effects on atopic dermatitis, would healing, acne and rosacea. There is now also emerging evidence for the benefits of topic probiotics on these conditions.19-22

IBS – prevalence of IBS in the general population is estimated to be between 10% and 20%.17 Studies have shown that probiotics are both effective and safe at relieving IBS symptoms, including abdominal pain, through manipulation of the gut microbiota.23-27

A recent meta-analysis review showed that Lactobacillus acidophilus ranked first as a single strain to alleviate IBS symptoms. A mixture containing five probiotics (including L. plantarum, L. casei, Bifidobacterium longum, streptococcus thermophilus and L. acidophilus) ranked first in improving the IBS-Quality of life.

Bacillus coagulans was among the most effective probiotics for improving abdominal pain.28

Diarrhoea – Probiotics have shown promise for the prevention of antibiotic-associated diarrhoea.

Oral health – probiotics usage could be beneficial for the maintenance of oral health, due to its ability to decrease the colony forming unit counts of oral pathogens.29

Vaccine response – The immunomodulatory effects of probiotics may influence the response to vaccines and may improve vaccine efficacy and duration of protection.30

Inflammation and oxidative stress – probiotics improved cognitive performance in Alzheimer’s disease or patients with mild cognitive impairment through decreasing levels of inflammatory and oxidative biomarkers.31

Viral infections – Probiotics have shown effectiveness for the treatment and prevention of viral infections, as well as a supportive role in enhancing immune response.32

Insulin Resistance – a recent study suggests administration of the probiotic Lactobacillus Rhamnosus GG33 can attenuate diet induced insulin resistance, also Saccharomyces Boulardii has therapeutic benefits to metabolic syndrome.34

Further studies support the use of probiotics in respiratory conditions, urinary tract infections, metabolic syndrome, the list is endless.

Given the extensive list of factors that can contribute to an unbalanced gut flora and the numerous conditions and symptoms that are associated, it is likely that most of us will be able to identify with one or many of these, and so including a probiotic may be beneficial.

What to look for in a probiotic?

Probiotics are some of the safest natural supplements available and have very few contraindications. It is worth making sure however, that:

  • The probiotic supplement can reach its site of action, usually the gut, and thus survive the stress of the stomach acid, pancreatic juices, and bile salts. Consider a probiotic which contains technology to further protect it from degradation by stomach and bile acids, such as Cytoplan’s GUARD technology which also allows time release of probiotics in the intestine.
  • The strains of bacteria contained should be backed by research showing a beneficial effect.
  • It can be useful to include a probiotic that contains additional prebiotics such as FOS or inulin, these provide a source of fuel for the gut flora and can help support its growth and diversity.
Further information on the probiotics we use

Cytoplan is currently developing a large probiotic dossier, highlighting the properties, technical information, wealth of clinical research and trials which support the use of the strains in our probiotic supplements.  Please contact us for further information.

Key Takeaways

  • Gut is a complex ecosystem where gut flora, nutrients, and own cells should interact as a symbiotic partnership – but often does not.
  • Functions of gut flora include assisting digestion, vitamin production, protection against pathogens, and serving as a communication centre.
  • Pre-natal, neo-natal, post-natal factors can impact on the development of the gut flora
  • Host of other factors can disturb the ratio of good-to-bad bacteria – food choices, stress, poor sleep, pollution, disease, medications, antibiotics.
  • An imbalanced gut flora is referred to as ‘dysbiosis’ and can lead to many gut-specific symptoms many symptoms beyond the gut.
  • Nutrition has profound effects on microbial composition, in turn affecting wide-ranging metabolic, hormonal, and neurological processes
  • Westernised diet is characterised by a low intake of fibre. Dietary fibre promotes beneficial bacteria.
  • An unbalanced gut flora can present itself through disturbances specific to the gut, craving sugar, weight gain, food sensitivities, fatigue, yeast infections, skin reactions and mood problems.
  • Probiotics are live micro-organisms and help to support a healthy balance of bacteria in the gut.
  • There is an abundance of evidence linking probiotic use to a wide range of conditions and complaints including IBS, viral infections, mood disorders, skin conditions, oral health, immune disorders.
  • Important to make sure the probiotic supplement can reach its site of action and the strains contained are backed by research showing a beneficial effect. 


  1. Jones R, et al. Management of common gastrointestinal disorders: quality criteria based on patients’ views and practice guidelines. Br J Gen Pract. 2009;59(563):e199-208.
  2. Valdes, A.M. et al. (2018) “Role of the gut microbiota in nutrition and health,” BMJ, 361, pp. 36–44. doi:10.1136/BMJ.K2179.
  3. New Prescription Medication Statistics | The Smart Clinics (no date). Available at: https://www.thesmartclinics.co.uk/new-uk-prescription-medication-statistics/
  4. Long-term conditions and multi-morbidity | The King’s Fund (no date). Available at: https://www.kingsfund.org.uk/projects/time-think-differently/trends-disease-and-disability-long-term-conditions-multi-morbidity
  5. LA, F., E, C. and SA, J. (2020) “Current explorations of nutrition and the gut microbiome: a comprehensive evaluation of the review literature,” Nutrition reviews, 78(10), pp. 798–812.
  6. Dietary Status Of Teens And Young Adults In Micronutrient Crisis (2020). Available at: https://www.hsis.org/wp-content/uploads/2020/12/HSIS_Dietary-Status-of-Teens_report_web.pdf
  7. ​​Armitage, R. and Nellums, L.B. (2021) “Antibiotic prescribing in general practice during COVID-19,” The Lancet Infectious Diseases, 21(6), p. e144.
  8. https://www.nbmedical.com/blog/overprescribing-functional-dyspepsia-and-ppwhys
  9. Is It Useful to Administer Probiotics Together With Proton Pump Inhibitors in Children With Gastroesophageal Reflux? (no date). Available at: https://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm17059
  10. Madison, A. and Kiecolt-Glaser, J.K. (2019) “Stress, depression, diet, and the gut microbiota: human–bacteria interactions at the core of psychoneuroimmunology and nutrition,” Current opinion in behavioral sciences, 28, p. 105.
  11. https://www.priorygroup.com/mental-health/stress-treatment/stress-statistics
  12. C, I. et al. (2020) “Effects of probiotics and paraprobiotics on subjective and objective sleep metrics: a systematic review and meta-analysis,” European journal of clinical nutrition, 74(11), pp. 1536–1549.
  13. Li, Y. et al. (2018) “The Role of Microbiome in Insomnia, Circadian Disturbance and Depression,” Frontiers in Psychiatry, 9, p. 669.
  14. Irwin C, McCartney D, Desbrow B, Khalesi S. Effects of probiotics and paraprobiotics on subjective and objective sleep metrics: a systematic review and meta-analysis. Eur J Clin Nutr. 2020 Nov;74(11):1536-1549.
  15. H, D. et al. (2020) “Gut microbiota: A target for heavy metal toxicity and a probiotic protective strategy,” The Science of the total environment, 742.
  16. Leaky Gut and Food Sensitivity – Oxford Biomedical Technologies, Inc. (no date). Available at: https://www.nowleap.com/what-is-meant-by-leaky-gut/
  17. H, W. et al. (2016) “Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review,” Journal of neurogastroenterology and motility, 22(4), pp. 589–605.
  18. Bistas KG, Tabet JP. The Benefits of Prebiotics and Probiotics on Mental Health. Cureus. 2023 Aug 9;15(8):e43217.
  19. Fijan S, Kolč N, Hrašovec M, Jamtvedt G, Pogačar MŠ, Mičetić Turk D, Maver U. Single-Strain Probiotic Lactobacilli for the Treatment of Atopic Dermatitis in Children: A Systematic Review and Meta-Analysis. Pharmaceutics. 2023 Apr 17;15(4):1256.
  20. Sánchez-Pellicer P, Navarro-Moratalla L, Núñez-Delegido E, Ruzafa-Costas B, Agüera-Santos J, Navarro-López V. Acne, Microbiome, and Probiotics: The Gut-Skin Axis. Microorganisms. 2022 Jun 27;10(7):1303.
  21. Menni A, Moysidis M, Tzikos G, Stavrou G, Tsetis JK, Shrewsbury AD, Filidou E, Kotzampassi K. Looking for the Ideal Probiotic Healing Regime. Nutrients. 2023 Jul 6;15(13):3055.
  22. Zhu W, Hamblin MR, Wen X. Role of the skin microbiota and intestinal microbiome in rosacea. Front Microbiol. 2023 Feb 10;14:1108661.
  23. R, K., T, K. and J, G. (2020) “The role of topical probiotics in skin conditions: A systematic review of animal and human studies and implications for future therapies,” Experimental dermatology, 29(1), pp. 15–21.
  24. Introduction  | Irritable bowel syndrome in adults: diagnosis and management  | Guidance | NICE” (2015).
  25. HL, X. et al. (2021) “Efficacy of probiotic adjuvant therapy for irritable bowel syndrome in children: A systematic review and meta-analysis,” PloS one, 16(8).
  26. B, L. et al. (2020) “Efficacy and Safety of Probiotics in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis,” Frontiers in pharmacology, 11.
  27. HL, N. and JY, X. (2020) “The efficacy and safety of probiotics in patients with irritable bowel syndrome: Evidence based on 35 randomized controlled trials,” International journal of surgery (London, England), 75, pp. 116–127.
  28. Xie P, Luo M, Deng X, Fan J, Xiong L. Outcome-Specific Efficacy of Different Probiotic Strains and Mixtures in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. Nutrients. 2023 Sep 4;15(17):3856.
  29. M, S.-A. et al. (2017) “Probiotics and oral health: A systematic review,” Medicina oral, patologia oral y cirugia bucal, 22(3), pp. e282–e288.
  30. P, Z. and N, C. (2018) “The influence of probiotics on vaccine responses – A systematic review,” Vaccine, 36(2), pp. 207–213.
  31. H, D. et al. (2020) “Efficacy of probiotics on cognition, and biomarkers of inflammation and oxidative stress in adults with Alzheimer’s disease or mild cognitive impairment – a meta-analysis of randomized controlled trials,” Aging, 12(4), pp. 4010–4039.
  32. Jayawardena, R. et al. (2020) “Enhancing immunity in viral infections, with special emphasis on COVID-19: A review,” Diabetes & Metabolic Syndrome, 14(4), p. 367.
  33. Arellano-García L, Macarulla MT, Cuevas-Sierra A, Martínez JA, Portillo MP, Milton-Laskibar I. Lactobacillus rhamnosusGG administration partially prevents diet-induced insulin resistance in rats: a comparison with its heat-inactivated parabiotic. Food Funct. 2023 Sep 12.
  34. Egea MB, Oliveira Filho JG, Lemes AC. Investigating the Efficacy of Saccharomyces boulardiiin Metabolic Syndrome Treatment: A Narrative Review of What Is Known So Far. Int J Mol Sci. 2023 Jul 27;24(15):12015

If you have questions regarding the topics that have been raised, or any other health matters, please do contact our team of Nutritional Therapists.

01684 310099

Last updated on 3rd January 2024 by cytoffice


6 thoughts on “Foundations of health part one: probiotics

  1. Thank you for this wonderful article. Much appreciated! I make kefir at home but I also will buy some of your probiotics .

  2. Feel so empowered by reading articles. Have become so sceptical of some doctors, how they communicate with me. I ask questions pertaining to my health, and why prescriptions that should not have been prescribed for me, I’m more inclined to read your articles and bolster my health, without being ignored by some professionals. At a recent consultation I was told not to Google information, and more disturbing – “I should not read the leaflet enclosed in prescriptions”! All because my knowledge of how prescribed medications were impacting negatively, on my health. Thank you so much for all your informative advice in all your articles. It helps me monitor my health and wellbeing, way more effectively.

    1. Thank you so much for your feedback – we are so pleased to hear that you feel empowered to make the best decisions for your own health and wellbeing.

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