The microbiome in the small and large intestine is a consortium of trillions of microorganisms (also called microbiota) of thousands of different species. These include not only bacteria, but also fungi, protozoa and viruses. The microbiota is an extremely rich and dynamic ecosystem where important functions take place such as fermentation of fiber into short-chain fatty acids, protein and complex carbohydrate metabolism, vitamin synthesis and other important functions. Some authors even consider the microbiome an additional supporting organ in the body, which is crucial for reaching a healthy state of the body.
The microbiome coexists in balance with the host’s body (symbiosis) and contributes to the proper gut function and homeostasis. Most of the microorganisms in the microbiome are symbiotic (helpful to the body), a smaller proportion are opportunistic (can harm the body if proliferate in large numbers) and a small proportion are pathogenic (harmful to the body). The healthy human microbiome contains multiple symbiotic strains such as bifidobacterium, lactobacillus, streptococcus, lactococcus, etc., which, in addition to playing important metabolic functions for the body, also produce antibacterial peptides that inhibit the development of pathogenic and opportunistic strains.
Environmental factors such as stress, infection, unhealthy eating habits, increased alcohol intake, continued use of antibiotics or other drugs may change the balance of the microbiome, destroy helpful bacteria and allow the proliferation of pathogenic and opportunistic strains.
The resulting imbalance in the microbiome ecosystem (dysbiosis) may cause digestive problems such as bloating, gas and diarrhea, a weakened immune system, increased risk of infections, gut inflammation, malabsorption of nutrients and mental health problems such as anxiety and depression.
Food plays a major role in determining the type of microbiota that lives in the colon. The high content of fiber, polyphenols and some saponins in the diet supplies the gut with a variety of molecules and substances nourishing the microbiome that actually have a prebiotic role, whereby development of helpful bacteria is potentiated.
Fiber is broken down by bacteria through fermentation, producing short-chain fatty acids such as acetate, propionate and butyrate. Short-chain fatty acids represent an important source of energy for colonic cells and play a role in regulating various physiological processes, including immune function and inflammation.
Polyphenols are metabolized through enzymatic reactions by bacteria, broken down into smaller molecules (postbiotics), and then absorbed by the body where they exhibit a range of biological activities such as antioxidant, anti-inflammatory and antimicrobial ones.
Some saponins, such as those found in ginseng, oats, soy, chestnuts, avocado and pumpkin seeds, act as prebiotics that selectively promote the growth and activity of helpful bacteria in the gut such as bifidobacteria and lactobacilli. Saponins have strong anti-inflammatory properties that protect the integrity of the gastrointestinal mucosa and prevent the transfer of harmful substances such as toxins and pathogens from the intestinal lumen into the bloodstream. This reduces the risk of systemic inflammation and infection.
Some of the best prebiotic foods are: yogurt, pickles, kefir, ginseng saponins, green tea polyphenols, artichoke inulin, etc.
Probiotic supplements may be a suitable source of helpful bacteria, but due to poor regulation low quality products are very often available and advertised in the open market. It is important to know that since probiotics contain live organisms more than half of the bacteria present in a product may die by the end of the first year of the date of manufacture. This process can be further accelerated by prolonged and improper storage of the probiotic.
It is necessary to select multistrain probiotics (10 to 15 strains) with the highest possible microbial count (at least between 5 to 10 billion per strain for most bacteria), thus ensuring intake of sufficient live microorganisms and good diversity in the microbiome ecosystem.
The presence of a prebiotic in a product contributes to the good development of helpful bacteria. The intake of probiotics needs to be with food in order for the bacteria to reach the intestine smoothly and not break down in the gastric juice.
