The statement that our health depends on the health of our gut is far from an exaggeration. Knowledge in this area has expanded with the development of a relatively new field in medicine—the microbiome, or the genome of the gut flora. This field has attracted increasing interest among scientists, and studies are leading to surprising results. When we talk about the microbiome, we’re referring to millions of genes—one of the most cited numbers is 3.3 million. In comparison, the human genome consists of only 20 to 25 thousand genes. The human body is home to a vast number of microorganisms—archaea, microscopic fungi, protozoa, and viruses, which are found on the skin and mucous membranes of every human body. We can say they form the body’s “normal microbiota.”
The gut microbiome is crucial for immunity and contains ten times more bacterial cells than human cells. Today, it is widely accepted that food, or at least some of its components, act as “hormones” or signaling molecules for the microbiome. There is already substantial evidence in animals indicating that the gut microbiome is responsible for overweight and obesity. In humans, the microbiome is acquired at birth, and subsequently, microbial diversity is enriched during the first 2-3 years of life. After that, the microbial flora gradually stabilizes until adolescence and remains stable through adulthood. Later in life, the microbiome becomes less diverse and less stable.
The gut microbiota actively participates in many metabolic processes in the human body. For example, with the help of the microbiome, vitamin K and biotin are synthesized, important nutrients are absorbed, the development of the mucosal immune system is supported, and a barrier function is provided by suppressing potentially harmful microorganisms. This is why we must care as much as possible for the health and diversity of our gut inhabitants. The intestinal microbiome is influenced by both exogenous and endogenous factors. Exogenous factors include dietary habits—the intake of plant fibers, indigestible carbohydrates, and bulk substances that act as prebiotics, or “food” for gut bacteria. Other external factors include lifestyle, medication intake, and dietary supplements. Endogenous factors are genetically determined and include bacterial mucosal receptors, intestinal pH, and immune cells. The integrity of epithelial cells and their specific binding pattern are crucial for the barrier function of the mucosa. The protective role of the intestinal epithelium prevents potentially harmful bacteria from entering systemic circulation. Disruption of this protective function is associated with “leaky gut” syndrome, systemic inflammation, and various autoimmune diseases.
Dysbiosis of the gut flora refers to an imbalance in the microbial community in terms of quantitative and qualitative changes, metabolic activity, and topographical distribution. Interestingly, the microbiota of overweight and obese individuals generates substrates that can activate lipogenic pathways, which means promoting fat storage.
We’ve all heard of probiotics and prebiotics. Probiotics are live microorganisms that improve the body’s internal microbial balance. In other words, they’re the “good” bacteria that live in our bodies. Probiotics help restore the natural balance in the gut and suppress the growth of harmful microbes. They can improve the immune system and overall health, and some strains may even help prevent allergy symptoms, reduce lactose intolerance, and more. Beyond supplements, it’s important to remember natural sources of probiotics, such as naturally fermented foods with lactic acid bacteria. A notable example is Lactobacillus bulgaricus, the bacteria in Bulgarian yogurt. Once isolated, scientists began extensive studies on Bulgarian yogurt, believing it to be a key to longevity due to its health benefits.
Incorporating dairy products into our daily diet is beneficial. Another example of natural probiotics is fermented foods like sauerkraut and certain pickles. Sauerkraut is rich in vitamins A, B, C, and K, as well as minerals. Fermented foods have a calming effect on the nervous system and strengthen immunity. Probiotics are also present in superfoods from the ocean, such as spirulina, chlorella, and blue-green algae. These probiotic foods increase the levels of lactobacilli and bifidobacteria in the digestive tract.
Prebiotics, on the other hand, are natural, indigestible food ingredients that affect metabolism by selectively stimulating the growth and activity of “good” bacteria in the large intestine, thus strengthening our health. In other words, prebiotics are the food for probiotics. To serve their purpose effectively, they must reach the intestines without being digested in the stomach. Prebiotics are found in vegetables, whole grains, and fiber-rich foods, also known as oligosaccharides. Additionally, they influence blood sugar levels, improve mineral absorption, and maintain their balance in the body. We often refer to prebiotics as “bifidogenic factors” due to their preferential stimulation of bifidobacteria growth.
Synbiotics, as the name suggests, are combinations of probiotics and prebiotics. When we consume good bacteria (probiotics) and their food (prebiotics) together, their effects on our health are enhanced. A natural example of a synbiotic is a combination like yogurt with banana or roasted asparagus with tempeh/miso. Probiotics, alone or in combination with other therapies, modulate microbial diversity and abundance and can therefore be recommended for various conditions, as well as alongside standard dietary and behavioral strategies.
As absurd as it sounds, the trillions of bacteria in our gut determine how we feel, think and look at every moment of our lives.
*Sources:
[1] 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.
[2] TsvetanVelinov, “Pulmonary microbiome and reasonable antibiotic therapy”, Inspiro magazine, no. 2(45), 2018
[3] Host genetic variation and its microbiome interactions within the Human Microbiome Project- Genome Med 2018 ,RaivoKolde