It is not even slightly exaggerated that our wellbeing depends on our gastrointestinal health. Our microbiome (or genome of the intestinal flora) is a relatively new field in medicine, and it has been expanding in the last few years. Many scientists are more and more interested in conducting research on how our intestines relate to our well-being. They have found that the microbiome consists of 3,3 million bacteria, whereas the human genome has only 20-25 thousand genes and the health of the microbiome is essential for immunity. The human body is home to a huge number of microorganisms- archaea, microscopic fungi, protozoa and viruses. All can be found on the skin and mucous membranes of the body.
It is now believed that food, or at least some of its constituents, play the role of signaling molecules to the microbiome. In animals, there is already a strong evidence to suggest that the intestinal microbiome is responsible for overweight and obesity. In humans, the microbiome is acquired at birth and then it is enriched during the first 2-3 years of life. After that, the microbiome flora stabilizes itself gradually until adolescence, and remains stable until adulthood unless it is disrupted by many external and internal factors. In the later stages of our lives, the microbiome becomes less diverse and its stability is not that good as before.
The intestinal microbiota is actively involved in many metabolic processes in the human body. For instance, it synthesizes vitamin K and biotin, it facilitates the absorption of important nutrients, forms the development of the mucosal immune system, and provides a barrier to a potentially dangerous microorganism. Thus, we should take the best possible care of our intestinal health and its diversity.
The intestinal microbiome is influenced by both exogenous and endogenous factors. Exogenous factors include our dietary and lifestyle habits- the intake complex carbohydrates and fibre, which play the role of prebiotics or “food” for the intestinal bacteria, the way we live, the intake of medicines or food supplements. Endogenous factors are genetically determined and include bacterial mucosal receptors, intestinal pH, immune cells. The epithelial cells as well as their specific way of binding, decide on the differentiating function of the mucosa. The protective role of the intestinal epithelium is to prevent potentially harmful bacteria from reaching the circulation. Any disruption of this protective function is associated with irritable bowel syndrome and the development of systematic inflammation as well as number of autoimmune diseases.
Any dysbiosis of the intestinal microflora can disturb the balance in the microbial community in terms of quantitative and qualitative changes and affect metabolic activity. Interestingly, the microflora of overweight and obese people generates substates that activate lipogenic pathways- or in other words- to favour fat storage. That is why, we should try and keep our guts as healthy as we can.
All of us have heard of the so-called probiotics and prebiotics. Probiotics are living microorganisms that improve a person’s internal microbial balance. Or we can say that these are the “good” bacteria that live in our body. Probiotics help restore the natural balance in the gut and suppress the development of pathogenic microbes. They can improve the human immune system and our overall well-being. Some strains can even help with the prevention of various allergic symptoms or the reduction of lactose intolerance.
Apart from being available as food supplements, we should not forget that probiotics exist in a natural form- fermented foods. It is thought that an extremely “good” microbe is Lactobacillus bulgaricus, which is the bacterium in the Bulgarian yogurt. After its isolation and many studies made with the strain, scientist claim that the consumption of yogurt is actually the secret of longevity. Thus, the addition of dairy products in our diet is vital.
Another example of a natural probiotic product is fermented sauerkraut and some types of pickles. Sauerkraut is rich in vitamins A, B, C and K as well as several minerals. Fermented foods have a calming effect on the nervous system and strengthen the immune system. Probiotics are found in some superfoods such as spirulina, cholera and blue-green alagae. These probiotic foods increase the number of lactobacilli and bifidobacterial in the digestive tract.
On the other hand, prebiotics are natural, indigestible nutrients that affect our metabolism by selectively stimulating the growth and activity of “good” bacteria in the colon. Therefore, they help strengthen our intestinal health. In other words, prebiotics are the food of probiotics. They are found in vegetables, wholegrains or in general- in foods rich in fiber and oligosaccharides. Additionally, they affect blood sugar levels, increase the absorption of minerals in the body and improve their balance. We often call prebiotics “bifidogenic factors” because of their tendency to act as stimulants of bifidobacteria.
Synbiotics, as their name suggests, are a combination of probiotics and prebiotics. When we take the food bacteria (probiotics) and their food (prebiotics) together, we can notice an improvement in their action which enhances their effect on the body. There are many supplements offering synbiotics, but if we want to keep it as natural as we can- a banana with yogurt is a good option to get both pro- and prebiotics.
Probiotics alone or in combination with other drug/supplemental therapy can modulate microbial diversity and abundance. Therefore, they may be helpful in many health conditions. As crazy as it may sound, the trillions of bacteria in our gut determine how we feel, think and look in every single moment of our lives.
 PeerJ. 2019 Aug 16;7:e7502. doi: 10.7717/peerj.7502. eCollection 2019. Factors affecting the composition of the gut microbiota, and its modulation. Hasan N1,2, Yang H1.
 Host genetic variation and its microbiome interactions within the Human Microbiome Project- Genome Med 2018 ,RaivoKolde