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Volume 9.13 24th Oct 2019

BACTERIA: THE GOOD, THE BAD AND THE UGLY More and more research is delving into the area of gut bacteria and its impact on health and disease, but what’s good bacteria and what’s bad and are probiotics the answer? As humans are born, their individual gut microbiota develops and is affected by the birthing process and early life. For example, whether an infant is breastfed or formula-fed, or whether the mother has taken antibiotics during pregnancy or lactation, it has been shown to result in a different balance of microbiota in the infant’s gut.3,4 Furthermore, differences in gut microbiota have been identified between those born via the vaginal canal or by caesarean section, though arguably other factors may be driving these differences, as critically discussed by Stinson et al.5 A multicentre European study by Fellani et al, found that breastfed infants had significantly higher proportions of Bifidobacteria (40.7% vs 29.2%, P<0.001) than formula-fed infants.6 Additionally, this study found that country of origin effected gut microbiota balance post weaning: infants from northern European countries had a higher proportion of Bifidobacteria, whereas infants from southern European countries had higher proportions of Bacteroides and Lactobacilli.6 It could be

considered that the types of foods an infant is weaned on and their overall dietary intake will help determine which bacteria dominate for life. It is the foods eaten long term, along with other factors, such as environmental temperature and individual physiology,2 that play key roles in gut microbiota development. Once developed, the microbiota of an individual is quite stable for life. However, there are some factors that can lead to gut flora changes, for example, antibiotic use, ageing, changes in diet such as drastic calorie changes, or altering macronutrient balance. Also, high-fibre diets are associated with increased diversity of microbiota.7 TYPES OF GUT BACTERIA

Numerous types have been identified in the human gut. However, the main two phyla are the Bacteroidetes and the Firmicutes.2 These two phyla differ in the efficiency of their metabolism. For example, a study by Turnbaugh et al showed that obese individuals and mice with a higher proportion of Firmicutes

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Priya Tew Freelance Dietitian, Dietitian UK Priya runs Dietitian UK, a freelance dietetic service that specialises in social media and media work, consultancy for food companies and private patient work.

Naomi Leppitt Dietitian Naomi is newly qualified, working as a Community Dietitian in Windsor.


NHD CPD eArticle

Volume 9.13 - 24th October 2019

Table 1. Types of intestinal microbiota found throughout the human gastrointestinal tract.10 Intestinal Microbiota Number Lactobacillus Streptococcus Staphylococcus Enterobacteriaceae Yeasts Clostridium Bifidobacterium Fusobacterium Bacteroides Eubacterium Peptostreptococcus

Stomach <103 CFU/ml ✓ ✓ ✓ ✓ ✓

Duodenum & Jejunum 102-105 CFU/ml ✓ ✓ ✓ ✓ ✓

bacteria had a higher capacity to harvest energy.8 The study also showed that when the microbiota was transplanted from obese mice to germ-free mice, they rapidly gained fat mass, despite a decrease in food consumption. In another study, the abundance of Bacteroidetes was shown to increase as obese individuals lost weight on different low-calorie diets with a correlation that was significant.9 With obesity being a challenging and multifaceted health concern, it is important to address gut microbiota, as it may be a contributing factor, together with genetics, diet and lifestyle. Throughout the human gastro-intestinal tract, the microbiota increases in both number and diversity, being affected by factors such as pH, transit time and nutrient availability.10 As the colon has the slowest transit time, a favourable pH and has plentiful available nutrients, the collection of microbiota is most varied and populated here. The intestinal microbiota has several beneficial roles: • Metabolism: – Synthesis of vitamin K*, some water-soluble vitamins and all essential and non-essential amino acids.2 – Absorption of nutrients:

Ileum & Caecum

Colon

103-109 CFU/ml ✓ ✓ ✓ ✓ ✓ ✓

1010-1012 CFU/ml ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓

- calcium, magnesium, iron; - lipid metabolism through bile acid metabolism.11 – Fermenting non-digestible carbohydrates, such as dietary fibre, resistant starches, cellulose, pectins, gums, unabsorbed sugars and alcohols:2 - Energy and other substrates can then be harvested and used. - Short-chain fatty acids are produced from the digestion of carbohydrate: butyrate has tumour suppressing activity,12 and this reduces levels of colonic cancer. *Escherichia coli and Salmonella enterica biosynthesise menaquinone-vitamin K2, which is an essential nutrient that humans and other mammals cannot synthesise themselves.13 • Immunomodulation: – Effects composition of the gut-associated lymphoid tissue (GALT): - Intestinal epithelial cells can avoid patho genic impact by signalling receptors of the innate immune system to bind to bacteria associated substances.2 In response, the body protects itself from pathogenic microbes.

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Defence against harmful microbes by competing for binding sites on the intestinal wall, competing for available nutrients and by producing antimicrobial compounds.2

THE BAD AND THE UGLY

Sufferers of IBS will be well aware of the side effects of certain bacteria. Some fermentable carbohydrates are poorly absorbed by the intestinal system. Upon ingestion of these FODMAPS, there is osmotic action, where fluid is drawn into the lumen of the colon,14 and they are also fermented by bacteria in the colon, producing methane and or hydrogen gas.15 Together, these produce the commonly experienced symptoms of bloating, flatulence, abdominal pain and loose stools. Evidence shows that disturbances to the microbiota may contribute towards IBS developing, with faecal analysis of individuals with IBS showing significantly lower amounts of Lactobacilli and Bifidobacteria and increased proinflammatory Enterobacteriaceae.16 A meta-analysis found the Bifidobacteria, Lactobacillus, Escherichia coli and Enterobacter were significantly altered between IBS patients and healthy controls.17 When the gut microbiota is imbalanced, research is revealing links with disease states. Examples include inflammatory bowel disease and conditions related to systemic inflammation such as Type 2 diabetes and obesity, as well as a tendency towards allergy.2 Food that isn’t sanitary can severely disrupt the composition of the microbiota, or cause small intestine bacterial overgrowth (SIBO), leading to chronic malabsorption of nutrients, chronic inflammation and increased intestinal permeability. This can then lead to systemic inflammation, malnutrition, faltering growth and stunting.18 Allergies may be a result of altered microbiota composition in early life, through the hypothesis that this stimulates the immune system and ‘trains’ it to respond to antigens. But this happens disproportionately, leading to allergic reactions.2 Cardiovascular health is also related to microbiota, as described in a review by Tang et al: atherosclerotic plaques contain bacterial DNA the same as that found in the gut; metabolites generated by gut microbiota have been found to

Volume 9.13 - 24th October 2019

be a factor in the development of cardiovascular disease development. Microbiota may also have a role in blood pressure regulation; gut permeability results in bacterial translocation and systemic inflammation, which has been identified in patients with heart failure.19 WHAT ARE PROBIOTICS?

The term probiotic was first coined in the 60s and it was defined by the FAO/WHO and later updated as ‘live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.20,21 Probiotics are classified according to their strain, as the effects of a particular bacteria are strain-specific and not always the same across all bacteria of the same species. However, benefit can be attributed to a whole class, such as Bifidobacterium or Lactobacillus.21 In addition, a probiotic must be seen, in controlled studies, to have benefits to health. Identifying and quantifying the health benefit to the host is a challenging area to research, due to the effects of probiotics being numerous and multifactorial and often through multiple mechanisms and sites of action. Probiotics are differentiated from gut bacteria by the fact they’ve been isolated and have credible health effects. Fermented foods are not considered probiotics, as though they may have health promoting effects, each batch may have different bacteria and in different amounts. Also, though evidence is expanding into the area of the health benefits of faecal transplants, these are not classified as probiotics as the bacteria differs from donor to donor. HOW CAN THEY INFLUENCE THE GUT?

The mechanisms of probiotics are complex and depend on the strain and the site at which they act. For example, consensus research has shown that probiotics may compete with pathogens for essential nutrients, or for binding sites on the intestinal lining, they may produce antimicrobial substances, or short-chain fatty acids, improve transit, stabilise the intestinal barrier, or have roles in immunomodulation, or mucin production.10

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NHD CPD eArticle

Volume 9.13 - 24th October 2019

Sufferers of IBS will be well aware of the side effects of certain bacteria. Some fermentable carbohydrates are poorly absorbed by the intestinal system.

The unique balance of microbiota in any individual is relatively stable and resistant to change, generally returning to normal after disturbances such as antibiotics, immunosuppression and other factors.10 During antibiotic therapy, the benefit of probiotics may have greater influence.10 The World Gastroenterology Organisation reports the guidelines for clinical recommendations based on evidence for probiotic use in different diseases.22 For patients with IBS that choose to try probiotics, NICE guidelines advise trying them for a minimum of four weeks, while monitoring the effects, at the dose recommended by the manufacturer.23 This is to test whether that probiotic beneficially alters microbiota composition resulting in alleviated symptoms. The BDA advise that probiotics may be unlikely to provide substantial benefits.24 Probiotics using

lactic acid bacteria are considered safe as they have a long-term history of safe use in food.10 HOW CAN I PICK AN APPROPRIATE PROBIOTIC?

The International Scientific Association for Pre and Probiotics (ISAPP) recommends asking the following questions: Does it correlate to the dose used in studies? Does it provide an effective dose? Is it safe? What are the known health benefits associated with that strain? Does it provide the benefit being sought? Also, check the label. Does it give the full name of the strain; the number of live organisms in each dose (Colony forming units, CFU); the suggested dose; storage information and best before date; company information. Note: If an individual has acute pancreatitis of multiorgan failure, lactic acid is not advised. Probiotics and live yoghurts are also not advised for those on neutropenic diets

dieteticJOBS.co.uk To place an ad or discuss your requirements please call

01342 824 073

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NHD CPD eArticle Volume 9.13 - 24th October 2019

Questions relating to: Bacteria: the good, the bad and the ugly Type your answers below, download and save or print for your records, or print and complete by hand. Q.1

What can affect the makeup of a newborn’s gut microbiota?

A

Q.2

What are the two main phyla in the human gut and how do they differ in the efficiency of their metabolism?

A

Q.3

Summarise the beneficial roles of intestinal microbiota for: (a) metabolism; (b) immunomodulation

A

Q.4

Why are IBS sufferers well aware of the side effects of certain bacteria?

A

Q.5

How does food that isn’t sanitary affect microbiota?

A

Q.6

What are probiotics?

A

Q.7

Why is it noted that an individual’s unique balance of microbiota is relatively stable?

A

Q.8

What advice is given for patients with IBS who choose to try probiotics?

A

Q.9

When are probiotics and live yoghurts not advised?

A

Please type additional notes here . . .

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NHD CPD eArticle Volume 9.13 24th Oct 2019

References 1 Valdes AM, Walter J, Segal E, Spector TD. Role of the gut microbiota in nutrition and health. BMJ [Internet]. 2018. Jun 13 [cited 2019 Jul 27]; 361: k2179. Available from: www.ncbi.nlm.nih.gov/pubmed/29899036 2 Bull MJ, Plummer NT. Part 1: The Human Gut Microbiome in Health and Disease. Integr Med (Encinitas) [Internet]. 2014. Dec [cited 2019 Jul 27]; 13(6): 17-22. Available from: www.ncbi.nlm.nih.gov/pubmed/26770121 3 Soto A, Martín V, Jiménez E, Mader I, Rodríguez JM, Fernández L. Lactobacilli and bifidobacteria in human breast milk: influence of antibiotherapy and other host and clinical factors. J Pediatr Gastroenterol Nutr [Internet]. 2014. Jul [cited 2019 Jul 27]; 59 (1): 78-88. Available from: www.ncbi.nlm.nih.gov/pubmed/24590211 4 Baumann-Dudenhoeffer AM, D’Souza AW, Tarr PI, Warner BB, Dantas G. Infant diet and maternal gestational weight gain predict early metabolic maturation of gut microbiomes. Nat Med [Internet]. 2018. Dec 29 [cited 2019 Jul 27];.24(12): 1822-9. Available from: www.nature.com/articles/s41591-018-0216-2 5 Stinson LF, Payne MS, Keelan JA. A Critical Review of the Bacterial Baptism Hypothesis and the Impact of Cesarean Delivery on the Infant Microbiome. Front Med [Internet]. 2018 [cited 2019 Jul 27]; 5: 135. Available from: www.ncbi.nlm.nih.gov/ pubmed/29780807 6 Fallani M, Amarri S, Uusijarvi A, diger Adam R, Khanna S, Aguilera M et al. Determinants of the human infant intestinal microbiota after the introduction of first complementary foods in infant samples from five European centres. Microbiology [Internet]. 2011 [cited 2019 Jul 27]; 157: 1385-92. Available from: www.gla.ac.uk/departments/ 7 Krajmalnik-Brown R, Ilhan Z-E, Kang D-W, DiBaise JK. Effects of gut microbes on nutrient absorption and energy regulation. Nutr Clin Pract [Internet]. 2012. Apr [cited 2019 Jul 28]; 27(2): 201-14. Available from: www.ncbi.nlm.nih.gov/ pubmed/22367888 8 Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature [Internet]. 2006 Dec [cited 2019 Jul 28]; 444(7122): 1027-31. Available from: www.nature.com/articles/nature05414 9 Ley RE, Turnbaugh PJ, Klein S, Gordon JI. Human gut microbes associated with obesity. Nature [Internet]. 2006 Dec 21 [cited 2019 Jul 28]; 444(7122): 1022-3. Available from: www.nature.com/articles/4441022a 10 Council for Agricultural Science and Technology (CAST). Probiotics: Their Potential to Impact Human Health. [Internet]. Ames, Iowa; 2007 [cited 2019 Jul 27]. Report No: Issue Paper 36. Available from: www.castscience.org/download.cfm?PublicationID=2930&File=f030d2d5777f5676ed033b112a7e65524518 11 Long SL, Gahan CGM, Joyce SA. Interactions between gut bacteria and bile in health and disease. Mol Aspects Med [Internet]. 2017. Aug 1 [cited 2019 Jul 28]; 56:54-65. Available from: www.sciencedirect.com/science/article/pii/S0098299716301200 12 Gupta N, Martin PM, Prasad PD, Ganapathy V. SLC5A8 (SMCT1)-mediated transport of butyrate forms the basis for the tumor suppressive function of the transporter. Life Sci [Internet]. 2006. Apr 18 [cited 2019 Jul 28]; 78(21): 2419-25. Available from: www.sciencedirect.com/science/article/abs/pii/S0024320505011276 13 Meganathan R, Kwon O. Biosynthesis of Menaquinone (Vitamin K2) and Ubiquinone (Coenzyme Q). EcoSal Plus [Internet]. 2009. Aug [cited 2019 Jul 27]; 3(2). Available from: www.ncbi.nlm.nih.gov/pubmed/26443765 14 Barrett JS, Gearry RB, Muir JG, Irving PM, Rose R, Rosella O et al. Dietary poorly absorbed, short-chain carbohydrates increase delivery of water and fermentable substrates to the proximal colon. Aliment Pharmacol Ther. 2010; 31(8): 874-82 15 Ong DK, Mitchell SB, Barrett JS, Shepherd SJ, Irving PM, Biesiekierski JR et al. Manipulation of dietary short-chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome. J Gastroenterol Hepatol. 2010; 25(8): 1366-73 16 Rodiño-Janeiro BK, Vicario M, Alonso-Cotoner C, Pascua-García R, Santos J. A Review of Microbiota and Irritable Bowel Syndrome: Future in Therapies. Adv Ther [Internet]. 2018. Mar 1 [cited 2019 Jul 28]; 35(3): 289-310. Available from: http:// link.springer.com/10.1007/s12325-018-0673-5 17 Zhuang X, Xiong L, Li L, Li M, Chen M. Alterations of gut microbiota in patients with irritable bowel syndrome: A systematic review and meta-analysis. J Gastroenterol Hepatol [Internet]. 2017. Jan 1 [cited 2019 Jul 28]; 32(1): 28-38. Available from: http:// doi.wiley.com/10.1111/jgh.13471 18 Watanabe K, Petri WA. Environmental Enteropathy: Elusive but Significant Subclinical Abnormalities in Developing Countries. 2016 [cited 2019 Jul 28]; Available from: http://creativecommons.org/licenses/by/4.0/ 19 Tang WHW, Kitai T, Hazen SL. Gut Microbiota in Cardiovascular Health and Disease. Circ Res [Internet]. 2017. Mar 31 [cited 2019 Jul 28]; 120(7): 1183-96. Available from: www.ncbi.nlm.nih.gov/pubmed/28360349 20 Food and Agriculture Organisation of the United Nations, World Health Organisation. Guidelines for the Evaluation of Probiotics in Food: Report of a Joint FAO/WHO Working Group on Drafting Guidelines for the Evaluation of Probiotics in Food [Internet]. London Ontario, Canada; 2002 [cited 2019 Jul 27]. Available from: www.fao.org/es/ESN/Probio/probio.htm 21 Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B et al. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic [Internet]. Vol 11, Nat Rev. Gastroenterol. Hepatol. 2014 [cited 2019 Jul 27]. Available from: www.nature.com/nrgastro 22 Guarner F, Sanders ME, Eliakim R, Fedorak R et al. World Gastroenterology Organisation Global Guidelines Probiotics and prebiotics [Internet]. 2017 [cited 2019 Jul 30]. Available from: www.worldgastroenterology.org/UserFiles/file/guidelines/probiotics-andprebiotics-english-2017.pdf 23 NICE. Irritable bowel syndrome in adults: diagnosis and management. Clinical Guideline [CG61] [Internet]. NICE; 2008 [cited 2019 Jul 30]. Available from: www.nice.org.uk/guidance/cg61/chapter/1-Recommendations 24 McKenzie YA, Bowyer RK, Leach H, Gulia P, Horobin J, O’Sullivan NA et al. British Dietetic Association systematic review and evidence-based practice guidelines for the dietary management of irritable bowel syndrome in adults (2016 update). J Hum Nutr Diet. 2016; 29(5): 549-75.

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NHD CPD eArticle Vol 9.13  

BACTERIA: THE GOOD, THE BAD AND THE UGLY By Priya Tew and Naomi Leppitt

NHD CPD eArticle Vol 9.13  

BACTERIA: THE GOOD, THE BAD AND THE UGLY By Priya Tew and Naomi Leppitt

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