Why do we need healthy bacteria in our gut?
There are about 40 trillion microbes that live in, and on, us. More or less the same number of the total number of cells in our bodies (37 trillion) (1)(2). The microbes in our gut – the majority of which occupy the large intestine – comprise mainly of bacteria, but also fungi, viruses and other single- and multi-cellular organisms (3). All of these organisms create an adaptive ecosystem, which we call gut microbiome, gut microbiota or gut flora.
When our gut flora is healthy, beneficial bacteria and microbes flourish and control the harmful ones. However,
- intestinal symptoms, such as bloating, abdominal pain, constipation and diarrhoea
- inflammatory bowel disease (Ulcerative c
olitis and Crohn’s disease)
- diabetes (Type 1 and 2)
- bad sleep
- rheumatic diseases
- chronic kidney disease
- autoimmune diseases
- allergic diseases
Moreover, the composition of gut flora has been implicated in a variety of stress-related conditions including anxiety, schizophrenia, depression and irritable bowel syndrome (IBS) (5). This is because 90% of the body’s serotonin – our ‘feel-good’ chemical – is made in the digestive tract with the help of the gut microbes (6).
Factors that can change the composition of the gut microbiome include (4):
- the use of antibiotics
- illness and infections
- bad dietary habits
- lack of breastfeeding
- birth by Caesarean section
- produce a variety of vitamins including B3, B5, B6, B9 (folate), B12, biotin, vitamin K
- affect the absorption of key minerals such as iron
- activate and destroy toxins and mutagens
- transform bile acid and hormones
- promote the integrity of gut defence barriers which prevent harmful bacteria from entering the body
What should we eat to promote healthy gut flora?
What we eat plays a significant role in the shaping of our microbiome. Through the use of prebiotics and probiotics in our daily diet, we have the potential to change the composition of our gut flora (9).
Prebiotics is a name given to plant foods which provide indigestible fibre that our gut bacteria feed on. Fibre, which we as humans can’t break down, is passed into the colon undigested. It is then fermented by our gut bacteria to provide nutrients for them to grow and multiply. Therefore, including a rainbow of plant foods daily is necessary to cultivate the most beneficial strains in our gut (10).
Fibre is found in most vegetables and fruits, and in order to ensure that we get the most of it, you should:
- eat the skin of the fruits
- have some of your vegetables raw
- not rely solely on juices as they don’t contain fibre. Have juices as part of a healthy balanced diet
Some vegetables (leeks, asparagus, chicory, Jerusalem artichokes, garlic, onions) contain more insoluble fibre than others. More insoluble fibre means it is more fermentable for the gut bacteria, and as a result, consuming large amounts of these vegetables can cause bloating and discomfort in some cases, so start with small amounts (11). The same applies to fermented foods, especially if you have never had them before, so start with small portions and build up daily.
Probiotics are foods and beverages that contain live bacteria culture. Such foods include kefir, yoghurt, sauerkraut, kimchi and kombucha. Nowadays, sauerkraut and kimchi can be found in health food shops and supermarkets. However, make sure you get raw, non-pasteurised varieties to ensure it is alive and teaming with beneficial lactobacteria (8).
What about probiotics supplements?
Probiotics can be helpful to supplement the diet in certain people as they can aid in the creation of a better environment for your gut flora. Various probiotics strains affect digestive health in different ways, so understanding the benefits of them may be beneficial when there is a specific health issue to address.
It is worth remembering that probiotics don’t colonise the gut, even though they have a beneficial effect on the gut flora by promoting its growth and immune responses against harmful microbes (12). Therefore, probiotics supplements shouldn’t be the only thing you rely on to establish and maintain your healthy gut microbiome, but a balanced and healthy diet should.