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As humans, we live symbiotically with our gut microbiome which utilises our food to produces important molecules that we are unable to do so by ourselves. This includes the breakdown of complex carbohydrates so we can use them as an energy source, produces vitamins, minerals and short chain fatty acids, protect against pathogens and support immune system messenging amongst others. In this way, our own health has been shown to be dependent on the health of our gut microbiome.

Our gut is first populated with beneficial bacteria through vaginal childbirth and then through breast feeding. Breastfeeding ensures that the infant’s gut microbiome is continually developing and is high in beneficial Bifidobacterium which can digest the sugars in breast milk(i). Whilst it is not always possible to breast feed or give birth naturally, there are plenty of things that we can do to ensure that our gut is populated with as many beneficial bacteria as possible. Studies have demonstrated that a diverse range of gut bacteria has been shown to be beneficial to health but many of us have a depleted range due to a poor diet and lifestyle. Eating a healthy diet and exercising can help promote the growth of the beneficial bacteria which protect against potentially pathogenic bacteria. The beneficial bacteria also help to digest and absorb nutrients, synthesise nutrients, messenger molecules and boost our immune system and protect against carcinogens and other disease causing organisms. There are hundreds of different species of gut bacteria and a healthy individual usually has a diverse range of gut bacteria like all healthy ecosystems(ii). The more diverse the diet, the more diverse the gut microbiome and more it can adapt to changes(iii). Sadly, the average Western diet is high in sugar and fat and not very diverse. The best way to promote the beneficial bacteria is eat a wide range of fruit and vegetables, wholegrains(iv), legumes, fermented foods and gut promoting foods as possible(v). These foods are often high in fibre which our body cannot digest, but the gut microbiome can and this can promote their growth.

Bifidobacteria and lactobacilli are beneficial bacteria which can reduce inflammation and improve gut health. Fermented foods are altered by bacteria or yeast to convert the sugar to alcohol or organic acids. Yoghurt, kefir, kimchi, kombucha, sauerkraut and tempeh are all fermented foods. Many of these foods are high in beneficial lactobacilli and can prevent the growth of enterobactericeae, a type of bacteria which is linked to inflammation and chronic diseases(vi). In contrast, artificial sweeteners such as aspartame have been found to promote the growth of chronic disease causing bacteria such as Clostridium and Enterobacteria(vii). It is therefore best to eat live plain yoghurt rather than those with sugar or artificial sweeteners. Probiotics, prebiotics and synbiotics help to beneficial bacteria to flourish in the large colon. These are especially important when the gut defence mechanisms fail. Probiotics are live bacteria and yeast which promote health, particularly in the gut microbiome. Whilst probiotics don’t permanently colonise your gut, they can change the composition of the gut microbiome and are particularly important when the gut bacteria have been compromised by infection or antibiotics or other drugs(viii). The main problem with probiotics is the efficacy of whether the probiotic reaches the colon or is digested. There are probiotics that can navigate the digestive system such as Symprove and other foods such as live yoghurt where the beneficial bacteria do reach the large colon. Prebiotics are foods that promote the growth of beneficial microbes in the gut and improve health. Most prebiotics are fibre based or complex carbohydrates or resistant starch which the beneficial bacteria digest for fuel. Inulin, high in Jerusalem artichokes, onions, garlic, asparagus, is a water soluble prebiotic which naturally ferments and provides fuel for the beneficial bacteria including Bifidobacterium(ix). This stimulates the growth of beneficial bacteria and decreases the number of harmful parasites, yeast and bacteria that trigger inflammation.

Symbiotics are food ingredients or dietary supplements which contain both probiotics and prebiotics working in synergy to promote the growth of a particular type of bacteria. They were developed as many probiotics were having difficulty in surviving the digestive process. These novel products are still in development and will be a welcome addition to tackling the over use of antibiotics which can eradicate the beneficial bacteria.

In summary, eat a diet rich in fruit, vegetables, wholegrains, legumes and fermented foods to improve your gut microbiome which in turn improves your own health and well being preventing disease. References: i. Cell Host Microbe. 2015 May 13;17(5):690-703. Dynamics and Stabilization of the Human Gut Microbiome during the First Year of Life. Bäckhed et al ii. Mol Metab. 2016 Mar 5;5(5):317-20. A healthy gastrointestinal microbiome is dependent on dietary diversity. Heiman et Greenway iii. Nature. 2012 Sep 13;489(7415):220-30. Diversity, stability and resilience of the human gut microbiota. Lozupone et al iv. Br J Nutr. 2008 Jan;99(1):110-20. Epub 2007 Aug 29. Whole-grain wheat breakfast cereal has a prebiotic effect on the human gut microbiota: a double-blind, placebo-controlled, crossover study. Costabile et al v. Food Funct. 2016 Apr;7(4):1788-96 Impact of increasing fruit and vegetables and flavonoid intake on the human gut microbiota. Klinder A et al vi. Br J Nutr. 2007 Jan;97(1):126-33. Composition and metabolism of the intestinal microbiota in consumers and non-consumers of yogurt. Alvaro et al vii. PLoS One. 2014 Oct 14;9(10):e109841.41.eCollection 2014. Low-dose aspartame consumption differentially affects gut micro biota-host metabolic interactions in the diet-induced obese rat. Palmnäs et al iii. BMJ Open. 2014 Aug 25;4(8):e005047. doi: 10.1136/bmjopen-2014-005047. Use of probiotics to correct dysbiosis of normal microbiota following disease or disruptive events: a systematic review. McFarland LV ix. Br J Nutr. 2005 Apr;93 Suppl 1:S13-25. Introducing inulin-type fructans. Roberfroid MB



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