It’s a well-known fact that an imbalance in gut flora (gut microbiome) can impact health and the trillions of bacteria living inside us are mostly in our gut.
Over 100 billion bacteria and over 100’s of different species live in the bowel alone. The bowel isn’t just somewhere where waste accumulates and water is absorbed!
So what exactly is our microbiome?
It’s the symbiotic microbial cells that live alongside us, whether that is within our bodies or on our skin. In other words, we live interdependently with the microbial cells. We provide them with an environment to live in and colonise and they provide us with numerous health benefits. If our microbiome is imbalanced between those organisms which are beneficial to our health and those that aren’t, it can have a detrimental effect. An imbalance in the gut microbiome (remember microbiota are throughout our bodies, not just in the gut!) is known as dysbiosis.
The gut microbiome has many functions including; boosting the immune system, producing toxins & antitoxins, synthesizing and degrading vitamins, producing short-chain fatty acids (more on this later) and inhibiting the growth of certain pathogens.
Given that beneficial bacteria live within us symbiotically and are so important to our health, it makes perfect sense to ensure we provide them with prebiotics, the food they need to stimulate their growth and activity. Prebiotics are indigestible plant fibres that pass through the upper gastrointestinal tract undigested and are fermented by the gut microbiome in the colon.
This has several benefits for us. The undigested large carbohydrates are digested, short-chain fatty acids are produced and the colonisation of the beneficial bacteria keeps pathogens in check. Fewer pathogens result in fewer bacterial by-products that impact digestion by inactivating digestive enzymes and breaking down bile salts.
The digestion of prebiotics by the gut bacteria results in the production of short-chain fatty acids such as butyric acid that supports the health of the intestinal lining. If the intestinal lining becomes damaged the tight junctions become ‘leaky’ allowing large molecules such as undigested proteins and microbes to cross the intestinal barrier and play a role in a systemic immune inflammatory response. Conditions associated with a leaky gut include inflammatory bowel disease, coeliac disease, rheumatoid arthritis, ankylosing spondylitis food allergies, and diabetes mellitus.
The short chain fatty acids also help promote digestion, support regular bowel movements, relieve diarrhoea and constipation and maintain electrolyte levels.
Good sources of prebiotics are chicory root, Jerusalem artichoke, garlic, leeks, onion, fennel, and sweet potato. They essentially help balance and maintain the diversity and growth of intestinal bacteria in the gut and in particular increase Lactobacilli and Bifidobacteria.
As well as providing our body with the prebiotics we can ensure a healthy happy gut by eating fermented foods that supply the probiotics in the first place; kefir, tempeh, natto, miso, kimchi, sauerkraut, yoghurt, and kombucha are all good sources.
Kombucha Nutrition
Kombucha is the fermentation of tea, generally black tea, with sugar added as a substrate for the fermentation process. Fermentation is the breakdown of the sugars by bacteria and yeast. The tea is fermented with a symbiotic colony of bacteria and yeast (SCOBY).
Kombucha Beneficial Compounds (Martínez Leal et al., 2018)
As well as increasing the number of beneficial bacteria in the gut kombucha produces beneficial compounds such as polyphenols, ethanol, and acetic acid during the fermentation process. Acetic acid is able to kill potentially harmful microorganisms and may be particularly effective against Candida.
Studies show that the total polyphenol content in kombucha shows a linear increase during fermentation time. Polyphenols are antioxidants providing protection against diseases related to oxidative stress such as cancer, cardiovascular disease, and neurodegenerative disease. Polyphenols also interact with gut flora and have been shown to increase bifidobacteria and lactobacilli.
The flavour of kombucha is dependent upon the fermentation time and the resulting chemical composition. Ethanol concentration increases with fermentation time and it has been suggested that ethanol may have a role in preventing cardiovascular disease. It is ‘The French Paradox’ that states moderate alcohol consumption raises HDL cholesterol and hence is protective against cardiovascular disease.
Do be aware though that contaminated or over-fermented kombucha can contain up to 3% of alcohol and can also cause serious health problems.
References:
Cummings J.H.*, J. H. and Macfarlane, G. T. (2002) ‘Gastrointestinal effects of prebiotics’, British Journal of Nutrition, 87(6), pp. 145–151. doi: 10.1079/BJNBJN/2002530.
Dimidi, E. et al. (2017) ‘Mechanisms of Action of Probiotics and the Gastrointestinal Microbiota on Gut Motility and Constipation’, Advances in Nutrition: An International Review Journal. doi: 10.3945/an.116.014407.
Martínez Leal, J. et al. (2018) ‘A review on health benefits of kombucha nutritional compounds and metabolites’, CyTA – Journal of Food. Taylor & Francis, 16(1), pp. 390–399. doi: 10.1080/19476337.2017.1410499.
Ridlon, J. M. et al. (2014) ‘Bile acids and the gut microbiome’, Current opinion in gastroenterology. doi: 10.1097/MOG.0000000000000057 [doi].
Visser, J. et al. (2009) ‘Tight junctions, intestinal permeability, and autoimmunity: Celiac disease and type 1 diabetes paradigms’, Annals of the New York Academy of Sciences. doi: 10.1111/j.1749-6632.2009.04037.x.
