Issue 138 Probiotics prebiotics and the future of gut health

PUBLIC HEALTH

PROBIOTICS, PREBIOTICS AND THE FUTURE OF GUT HEALTH Rebecca Gasche Registered Dietitian, Countess of Chester Hospital NHS Trust Rebecca has a keen interest and specialises in gastroenterology dietetics. She currently works in the community setting in the Chester area, running clinics and group sessions to manage a wide range of gastroenterology conditions.

The use of probiotics and prebiotics in gut health has been a controversial topic. This article hopes to pick apart the latest evidence and what we really should be recommending when it comes to looking after our gut.

Gut health? Not the most inspiring of names, but definitely a topic that is at the forefront of both scientific research and media headlines. The ever-growing evidence of the importance of looking after our gastrointestinal (GI) system and how this can impact on our overall health is hitting the headlines more and more frequently, with emphasis on a high fibre, diverse plant-based diet, to help our ‘good bacteria’ flourish.

THE GUT

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Our gut - or more scientifically known as our GI tract - is a functional organ to allow us to digest and absorb food. It is also the most heavily populated area of the body by bacteria. It ranges from our oral cavity, where digestion begins with mastication, before moving to the stomach and small and large intestine before reaching the rectum.1 The gut microbiota (previously referred to as gut flora) refers to the microbe population that lives within our GI tract. Within this gut microbiota exists a complex ecosystem of approximately 300 to 500 bacterial species, comprising nearly two million genes - which make up the microbiome.2 The number of bacteria within the gut is immense to say the least, as it is approximately 10 times that of all of the cells in the human body, and the collective bacterial genome is vastly greater than the human genome.3 The gut microbiota is now considered an important partner of human health, as it interacts with virtually all human cells. For this reason, there have been multiple studies looking into this area. In fact, in 2017,

approximately 4000 papers focusing on the gut microbiota were published, and between the years 2013 and 2017, more than 12,900 publications were devoted to the study of the gut microbiota. This represents more than 80% of the overall publications of the last 40 years (since 1977) on this topic, highlighting the fact that this field of research is not only blossoming, but there is a necessity for it to continue.4 The functions of the GI microbiota include modulation of the immune system, as it can form a protective barrier which decreases the chances of pathogen invasion. It also plays a role in bacterial metabolism, as it is able to breakdown non-digestible food products (for example, non-starch polysaccharides, oligosaccharides proteins and amino acids) into short-chain fatty acids. In addition to this, the composition of GI microbiota has been linked to human brain development and the effects on anxiety/motor control issues.1 Therefore, keeping our levels healthy and balanced is essential.

PROBIOTICS

The WHO describes probiotics as ‘live organisms that when administered in adequate amounts, confer a health benefit to the host’,5 and the concept of using them to aid health dates back to 1907, where it was first thought to replace harmful microbes with beneficial ones

by Nobel Laureate Elie Metchnikoff.6 Probiotics can come in varying forms, most commonly found in our supermarkets as yoghurts or drinks.

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WHAT TO LOOK FOR IN A PROBIOTIC A guide for healthcare professionals CHECK THE LABEL AND QUALITY

Does the label state the full strain name of the microorganism(s) in the product?

Does the label state the number of live cells of the probiotic strain(s) in the product?

NOTE: This should comprise three components: genus, species and strain identifier.

Yakult contains 1010 Lactobacillus casei Shirota per 100 ml, when refrigerated.

Genus (e.g. Lactobacillus), species (e.g. casei) and strain (e.g. Shirota) is stated in full on Yakult’s packaging.

This is equivalent to 6.5 billion live cells per 65ml bottle.

Contact the company.

Are there quality control procedures in place?

NOTE: This is necessary to ensure the product contains the correct strains and number of live microbial cells as stated on the label.

Yakult is acknowledged by experts to be a quality probiotic.

CHECK THE SCIENTIFIC EVIDENCE

Contact the company or access their HCP website, to find the supporting research.

NOTE: (i) Regulatory restrictions mean companies can share research information with HCPs but not the general public; (ii) Not all probiotic research papers can be found on medical literature databases.

The research evidence for Lactobacillus casei Shirota can be found at www.yakult.co.uk/hcp or by contacting science@yakult.co.uk

CHECK FOR GI TRACT SURVIVAL

CHECK FOR EFFICACY OF THE STRAIN

For oral probiotics, are there human intervention trials showing survival of the probiotic strain(s) through the gut?

Check for trials and studies for the probiotic and the particular patient problem

NOTE : In vitro or model studies are not proof of gut survival in vivo.

(important for assessment of safety).

There are several research papers describing human studies showing the gut survival of Lactobacillus casei Shirota.

See expert advice in ‘LcS Insight: HCP Study Day 2014’ and ‘Your Guide to Probiotics’.

For further support on what to look for in a probiotic or to access the research behind Yakult, then please visit www.yakult.co.uk/hcp contact science@yakult.co.uk or call 020 8842 7600 This resource is intended for healthcare professionals. Not to be distributed to patients.

PUBLIC HEALTH added to them, as most of the natural probiotics found in yoghurt products die during processing.

Commercial probiotic supplements are also available in the form of powders, tablets and liquids. Some fermented foods are natural sources of probiotics too, such as kefir (a fermented milk).

So, where to start? Currently, there is no form of probiotic that has been proven to work better than others. What is important in commercial products, however, is that the particular strains have the correct encapsulation to survive transit through our gut. This is strain specific.1 Most probiotics are bacterial, however, other microbes (e.g. yeast, fungi and viruses) also make up the human microbiota.7 Probiotics are named by their genus, then species and finally their strain. The most commonly proposed organisms are Lactobacillus and Bifidobacterium strains.

PREBIOTICS

What about prebiotics? Confused? Prebiotics are described as non-digestible, fermentable food components that result in the selective stimulation of growth and activity of one or a limited number of microbial genera/species in the GI microbiota that provide health benefits to the host.8 Prebiotics are resistant to digestion in the upper GI tract and are fermented by the gut microbiota. This in turn impacts on the growth and activity of specific bacteria. For those familiar with the low FODMAP diet, the term prebiotics may be ringing bells. This is because the most common classes of prebiotics are also FODMAPs – fructans (oligofructose, fructo-oligosaccharides) and galactans (galactooligosaccharides). Therefore, those following a low FODMAP diet for the management of IBS are in fact restricting prebiotics during the elimination phase of the diet.

THE EVIDENCE

There are many conditions to which probiotics are thought to have a benefit, from a wide range of GI disorders and diarrhoea to conditions such as allergies, dental caries and vaginosis.1 However, proven evidence for the use of probiotics remains lacking. There are only a few conditions to which the use of probiotics has been proven to be beneficial, including the following: 9-12

• • • •

Acute onset of infectious diarrhoea Antibiotic-associated diarrhoea The prevention of traveller’s diarrhoea The prevention of clostridium difficile (C. diff) associated diarrhoea • Helicobacter pylori eradication (as an additional therapy) • The prevention of pouchitis Despite the studies supporting the use of probiotics for these conditions, varying studies provide different outcomes, with results differing depending, for example, on the specific strain or the duration they are taken.

For IBS-D specifically, it is thought that a multistrain probiotic is best associated with significant improvement in symptoms in IBS-D patients and is well-tolerated.13 Results from this particular study indicate that probiotic supplementation confers a benefit in IBS-D and deserves further investigation.

Currently, probiotics are not recommended when following a low FODMAP diet. However, a study by Staudacher et al14 concluded that probiotics in combination with a low FODMAP diet improve the effects of Bifidobacteria abundance and stool acetate. The study also notes that more research is needed on the effect of the reintroduction of FODMAPs on the gut microbiota before a low FODMAP diet and probiotic therapy can be advised conjunctively.

Research on both live and bio yoghurts has also been unclear. For example, two different studies looking at probiotics and the prevention of antibiotic-associated diarrhoea have provided conflicting results. Conway et al demonstrated no benefit from taking standard or bio yoghurts, whereas Beniwal et al showed a reduction in the incidence of antibiotic-associated diarrhoea when yoghurts were introduced.15,16 A number of studies have looked at the effects of prebiotics on GI disorders. Randomised control trials looking at the effect of prebiotics on various diarrhoea-associated conditions concluded that prebiotics had no impact on the duration of antibiotic-associated diarrhoea, however, they may reduce the relapse rate of C. diff patients or reduce the incidence of traveller’s diarrhoea. These studies typically used placebo groups and an addition of a certain number of prebiotics to the diet per day.17-19 www.NHDmag.com October 2018 - Issue 138

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Although not ALL diseases begin in the gut a vast amount do, and with advances in medical research we are learning that the connection between a healthy gut and a healthy body is both profound and undeniable. Imbalance of the gut bacteria (dysbiosis) has been linked to a number of conditions including IBS, acute gastroenteritis and nosocomial infections. With over 6 scientific publications a day, this area of research is rapidly growing and changing our understanding of the roles of gut bacteria in a wide range of conditions.

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PUBLIC HEALTH It has been concluded that there is no effect on gut microbiota or disease activity in patients with Crohn’s disease and, therefore, specific prebiotic treatment is not advised in this patient group.20 Interestingly, two randomised controlled trials looking at prebiotics and functional bowel disorder/IBS concluded that the addition of some prebiotics at varying doses may reduce symptoms of abdominal pain, bloating and flatulence.21,22 This is obviously contradictory to other studies linking worsening symptoms of prebiotics and IBS and the basis of the low FODMAP diet, which reduces prebiotics in the diet to improve symptoms. It’s one example of how, even though prebiotics have been linked to worsening symptoms in IBS patients, considering the dose of prebiotics used, they may be worthwhile and ongoing research in this area is required.

When looking at the use of probiotics in the general healthy population, there currently lacks robust evidence to suggest that probiotics may be of any benefit. A recent systematic review concluded that there was no overall benefit of probiotics on bacterial diversity when trialled in healthy people.23 GUT-BRAIN AXIS

While on the subject of gut health, I wanted to touch on the gut-brain axis (GBA) which consists of communication between the central and the enteric nervous system, linking emotional and cognitive centres of the brain with peripheral intestinal functions. There is strong evidence to suggest that gut microbiota has an important role in these interactions between the gut and the nervous system, by interacting with the central

nervous system (CNS), by regulating brain chemistry and influencing neuro-endocrine systems associated with stress response, anxiety and memory function.

One study describes how many of these effects appear to be strain-specific, suggesting a potential role of certain probiotic strains as a novel adjuvant strategy for neurologic disorders.24 In addition to this, the effects of CNS on microbiota composition are likely mediated by a change of the normal luminal/mucosal habitat that can also be restored by the use of probiotics and possibly by diet. In clinical practice, an example of this interaction is constituted by conditions such as IBS, which is now considered to be a microbiome-GBA disorder.24 Further studies have also noted how probiotics can reduce the stress-induced release of cortisol, anxiety- and depression-related behaviour,25 and can reduce exam-induced stress in medical students.26 Also, studies have shown that probiotics significantly affect the areas of the brain that deal with emotions and sensation, when compared to a placebo.27 CONCLUSION

I’m sure the advice for the use of probiotics, prebiotics and how to manage our general gut health will continue to change. However, the current evidence suggests that the use of probiotics and/or prebiotics may be advised for patients suffering from certain GI conditions such as IBS, traveller’s diarrhoea and C. diff.

Evidence for the use of probiotics in other medical conditions, or in the healthy population remains limited; but ongoing research may change this, particularly with the focus of our gut microbiota and mood.

OptiBac Probiotics specialise in live culture supplements and uses some of the most researched strains in the world.

Find out more at www.optibacprobiotics.co.uk or contact our healthcare professionals support team at hcp@wrenlabs.com

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