The ‘microbiome’ is a term we hear a lot these days, but what exactly does it mean?
Your body is quite literally teeming with bacteria. They live on your skin, in your mouth, nose, respiratory tract, urogenital tract and of course your gut - they are collectively known as your microbiome. You are in essence a walking, talking ecosystem.
Where it all starts
We are born more or less sterile, but our first encounter with microbes is during birth when we pick up our mother's microbiota from the birth canal. A young infant will have around 100 different species of microbes in their microbiome, but by the age of three our interaction with our environment has increased this amount to over 1000, roughly that of an adult. Our microbiome continues to shift over the course of our lives, particularly around changes such as puberty, pregnancy and menopause, but also in response to illness, stress and diet. Our genes also influence our microbiome, as does the climate we live in, our occupation, our gender and our hygiene.
How do our gut microbes keep us healthy?
Around 70% of the cells that make up your immune system are found in the digestive tract, so an unhealthy gut can result in poor immune health, autoimmune conditions and inflammation. Most of our microbes live in the gut - around 1-2 kilos in the average adult, or some 100 trillion bacteria - a number that is 10 times greater than the number of cells in the human body. Some of these bacteria such as E.coli and salmonella are bad for us, as they can cause acute or chronic illness. Others however, live symbiotically within us in a mutually beneficial relationship that has evolved to enhance their life and ours. These bacteria are commonly referred to as “friendly bacteria” and play a very important role in health. They are responsible for a whole host of roles including:
Other functions of gut bacteria include:
They are also thought to contribute and influence health conditions as diverse as IBS, eczema, and rheumatoid arthritis and may even play a role in resilience, depression, anxiety, metabolism, stress and sleep.
Gut brain axis
We are becoming increasingly aware of the role of gut bacteria not only for our physical health but also our mental well-being. This is due to the two-way link between the bacteria in the gut and our brain – known as the gut-brain axis. Now, a research review suggests that probiotics taken by themselves or combined with prebiotics, may help to ease depression. L.acidophilus, L. casei, and B.bifidium were the primary strains used in these studies. Probiotics are thought to help by reducing inflammatory chemicals, such as cytokines, or may help direct the action of tryptophan, a chemical believed to play an important role in the gut-brain axis in psychiatric disorders.
Its all about balance
The beneficial bacteria in your gut are so important for your health that an imbalance, also known as dysbiosis, may encourage the overgrowth of yeasts such as candida, parasites and harmful pathogens which may cause various symptoms such as diarrhoea, constipation, bloating, wind, skin problems, allergies, recurring infections and thrush.
So what might cause an imbalance of gut bacteria?
Nourish the “good guys”
To help keep your intestinal flora in good shape, eating probiotic foods such as “live” yoghurt and fermented foods such as natto, miso, tempeh and sauerkraut is recommended. If you are suffering from dysbiosis, a live bacteria supplement is usually advised as it will contain more therapeutic levels of friendly bacteria.
Do you know the difference between prebiotics and probiotics?
Prebiotics – we can nourish the ‘probiotic’ bacteria that are resident in our gut by providing prebiotic fibre which acts as food for the good bacteria and stimulates their growth. Prebiotic fibre is found in foods including garlic, onions, leeks, asparagus, bananas, whole oats and chicory root.
Probiotics – these are living strains of bacteria that add to the population of good bacteria in our digestive system and are found in foods including “live” yoghurt and fermented foods such as sauerkraut, tempeh and miso, but can also be taken in the form of a probiotic supplement.