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 Furthermore, according to research conducted by YouGov, there are many people in the UK that don’t think about their digestive system when it comes to overall health and are more likely to think about their weight, teeth, sleep, and heart.2 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, where we provide food for the microbes that inhabit our gut and, in return, they help us maintain the health of our gut. In many of us, however, this partnership has broken down and can become detrimental to our health. Gut flora can be categorised in to different groups – beneficial or commensal; pathogenic; or benign. The microbiome is now best thought of as a virtual organ of the body.3
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.
Dysbiosis and leaky gut
An imbalanced gut flora is often referred to as ‘dysbiosis’ and can lead to many gut-specific symptoms. It can also lead to 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 chemicals that travel throughout the body and cause system-wide inflammation, potentially affecting anywhere. 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 is 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.
Diet and lifestyle
Currently, approximately half of the adult population are taking prescription medications,4 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.5 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 Westernized diet is also characterised by a low intake of fibre. Dietary fibre promotes beneficial bacteria, which ferment soluble fibre into short-chain fatty acids (SCFA’s). SCFA’s exert many important roles, including providing an energy source for human colonocytes, and having beneficial effects on glucose and energy homeostasis.3 SCFA’s 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.7 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 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.8
Proton pump inhibitors (PPI’s) 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. In 2016, approximately 58 million prescriptions for PPIs were dispensed in primary care in England.9 Long-term PPI administration has been shown to alter intestinal bacterial population by suppressing the gastric acid barrier10 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.11 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-wide stress survey, commissioned by the Mental Health Foundation, found that 74% of adults have at some point over the past year felt so stressed they felt overwhelmed or unable to cope.12
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 issue13 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.14 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.15
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.16
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 sugar – eating 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 gain – an 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?
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 groups called Lactobacillus and Bifidobacterium. Yeasts may also be beneficial 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 positive evidence linking probiotic use with 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. 13-15
Mood – a systematic review of human studies found that supplementing with bifidobacterium and lactobacillus strains for 1-2 months improved anxiety, depression, and memory.18
Skin conditions – a recent systematic review demonstrated that oral probiotics modulate the intestinal microbiome and are efficacious in treating topical skin conditions, such as atopic dermatitis, acne, and rosacea.19
IBS – prevalence of IBS in the general population is estimated to be between 10% and 20%.18 Studies have shown that probiotics are both effective and safe at relieving IBS symptoms, including abdominal pain, through manipulation of the gut microbiota.20-23
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.24
Vaccine response – The immunomodulatory effects of probiotics may influence the response to vaccines and may improve vaccine efficacy and duration of protection.25
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.26
Viral infections – Probiotics have shown effectiveness for the treatment and prevention of viral infections, as well as a supportive role in enhancing immune response.27
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 with it, it is likely that most of us will identify with one, or even many of these. Including a probiotic may therefore offer great benefit to many of us.
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.
- The strains of bacteria contained should be backed by research showing a beneficial effect.
- The gut is a complex ecosystem where gut flora, nutrients, and own cells should interact as a symbiotic partnership – but often does not.
- The functions of the gut flora include assisting digestion, vitamin production, protection against pathogens, and serving as a communication centre.
- Pre-natal, neo-natal, and post-natal factors can impact on the development of the gut flora.
- A 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 beyond the gut.
- Nutrition has profound effects on microbial composition, in turn affecting wide-ranging metabolic, hormonal, and neurological processes.
- The 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.
- It is important to make sure that the probiotic supplement can reach its site of action and the strains contained are backed by research showing a beneficial effect.
If you have questions regarding the topics that have been raised, or any other health matters, please do contact me by phone or email at any time.
Amanda Williams and the Cytoplan Editorial Team
- 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.
- Digesting the facts. [online] Available at: http://gutscharity.org.uk/wp-content/uploads/2016/08/DigestingTheFactsReport.pdf [Accessed 4th october 2021]
- 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.
- New Prescription Medication Statistics | The Smart Clinics (no date). Available at: https://www.thesmartclinics.co.uk/new-uk-prescription-medication-statistics/ (Accessed: September 30, 2021).
- 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 (Accessed: September 30, 2021).
- 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. doi:10.1093/NUTRIT/NUZ106.
- 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 (Accessed: June 7, 2021).
- Armitage, R. and Nellums, L.B. (2021) “Antibiotic prescribing in general practice during COVID-19,” The Lancet Infectious Diseases, 21(6), p. e144. doi:10.1016/S1473-3099(20)30917-8.
- Forgacs, I. (2008) “Overprescribing proton pump inhibitors,” BMJ, 336(7634), pp. 2–3. doi:10.1136/bmj.39406.449456.be.
- 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 (Accessed: September 30, 2021).
- 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. doi:10.1016/J.COBEHA.2019.01.011.
- Stressed nation: 74% of UK “overwhelmed or unable to cope” at some point in the past year | Mental Health Foundation (no date). Available at: https://www.mentalhealth.org.uk/news/stressed-nation-74-uk-overwhelmed-or-unable-cope-some-point-past-year (Accessed: September 30, 2021).
- 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. doi:10.1038/S41430-020-0656-X.
- Li, Y. et al. (2018) “The Role of Microbiome in Insomnia, Circadian Disturbance and Depression,” Frontiers in Psychiatry, 9, p. 669. doi:10.3389/FPSYT.2018.00669.
- Sleep Survey & Statistics | Chemist4u (no date). Available at: https://www.chemist-4-u.com/sleep-study/ (Accessed: September 30, 2021).
- 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. doi:10.1016/J.SCITOTENV.2020.140429.
- Leaky Gut and Food Sensitivity – Oxford Biomedical Technologies, Inc. (no date). Available at: https://www.nowleap.com/what-is-meant-by-leaky-gut/ (Accessed: September 28, 2021).
- 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. doi:10.5056/JNM16018.
- 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. doi:10.1111/EXD.14032.
- Introduction | Irritable bowel syndrome in adults: diagnosis and management | Guidance | NICE” (2015).
- 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). doi:10.1371/JOURNAL.PONE.0255160.
- B, L. et al. (2020) “Efficacy and Safety of Probiotics in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis,” Frontiers in pharmacology, 11. doi:10.3389/FPHAR.2020.00332.
- 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. doi:10.1016/J.IJSU.2020.01.142.
- 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. doi:10.4317/MEDORAL.21494.
- P, Z. and N, C. (2018) “The influence of probiotics on vaccine responses – A systematic review,” Vaccine, 36(2), pp. 207–213. doi:10.1016/J.VACCINE.2017.08.069.
- 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. doi:10.18632/AGING.102810.
- 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. doi:10.1016/J.DSX.2020.04.015.