The human gut is home to billions of microbes. This is over ten times more than the amount of our own human cells. In terms of weight this adds up to about 2 kg.
Most of the gut microbes are bacteria, but there are also yeasts and viruses, and their job is, for example, to produce vitamin K and short chain fatty acids (SCFA). Short chain fatty acids are the main source of energy for the cells lining your colon.
What about gut feelings?
Gut microbiota also contributes to the synthesis of the neurotransmitters that are essential for the brain. And in the brain, these neurotransmitters are known to have an impact on mood - on how happy or well we feel. And stress, for example, can affect the gut through the HPA axis (Hypothalamus-Pituitary-Adrenal cortex axis), which is the hormonal connection between the brain and the gut and an important neuroendocrine system that regulates stress reactions.
Stress can cause changes in the integrity and permeability of the gut, because the stress hormone known as cortisol can affect the intestinal mucous layer and microbiota. Thus stress can deteriorate the balance and viability of the gut microbiota and hence accommodate the entry of new, potentially harmful bacteria into the gut. When the permeability of the gut increases, ever larger molecules can enter blood circulation from the gut and cause the activation of the immune system.
So for the well-being of the mind it is also important to take care of the well-being of the gut. And vice versa: emotional well-being also affects the gut. Gut microbiota is easily disturbed by, for example, stress or antibiotics.
Well-being from dietary fibre
Gut microbiota is fed with the carbohydrates (fibres) that are not digested in the small intestine and travel to the large intestine. In practice this means that the amount and quality of the fibre in the food we consume affects our gut microbiota.
According to research, it seems that combining different types of fibres is most beneficial for the well-being of gut microbiota – so it is worth eating a wide range of various full-grain products, vegetables, fruits, berries and legumes.
It also seems that the amount and quality of the fat in our food affects gut microbiota, and this can have both direct and indirect effects on the well-being of the human body.
The way gut microbiota affects health and cognition has been, and continues to be, researched a lot. We are continuously learning more and more about the significance of gut microbiota and indeed, it could well be that our diets affect us primarily through the microbiota of our gut.