The microbiota is the community of microorganisms that live in symbiosis with their host – humans. The microbiome, on the other hand, comprises the entire genetic material of the microbiota, representing the collection of microbial genomes that contribute to the broader genetic profile of humans.
Very often, the terms microbiota and microbiome are used interchangeably.
The human microbiota is a diverse array of microorganisms that include bacteria, archaea (single-celled microorganisms), fungi, and even some protozoa and acellular viruses. Bacteria are by far the most numerous members of the human microbiome, with the bacterial population alone estimated to comprise between 75 trillion and 200 trillion individual organisms, whereas the human body itself consists of approximately 50 to 100 trillion body cells.
The enormous abundance of microbes suggests that the human body is, in fact, a “superorganism”, a complex combination of human and microbial cells and genes, representing a mixture of human and microbial characteristics.
The gastrointestinal tract, like every surface of the human body, is colonized by microorganisms, mainly bacteria.
This microecosystem plays a vital role in maintaining overall human health, it is a silent partner in the intestines, contributes to the production of certain vitamins, supports digestion, and strengthens the immune system…
In this way, they perform essential functions for the human body.” Each individual has their own unique microbiome that depends on many factors, such as geographical location, the individual’s genetic background, age, lifestyle, dietary habits, gastric secretion, use of antibiotics…
Disruption of the balance of the intestinal microbiome (dysbiosis) leads to health disorders.
BIFIDOBACTERIA
Bifidobacteria are live bacterial cultures and important components of the intestinal microbiota. They belong to the group of “good bacteria” that live in the intestines, prevent the growth and reproduction of pathogenic bacteria in the intestines and help maintain the balance of intestinal microflora. Representatives of the genus bifidobacteria are among the first microorganisms to inhabit, or colonize, the human gastrointestinal tract.
During the first few weeks of life, bifidobacteria may account for up to 60% of all bacteria present in the intestinal microbiota of infants. However, their numbers gradually decline as part of the natural ageing process.
Reduced levels of bifidobacteria have been associated with several diseases, and dietary supplements containing bifidobacteria may help relieve symptoms of certain diseases, as well as one of the most common gastrointestinal conditions, which is irritable bowel syndrome.
Researchers have discovered nearly 50 species of these beneficial bacteria, each thought to have different functions and health benefits.
Numerous clinical studies have demonstrated an association between the diversity of the gut microbiota and excess body weight, as well as the risk of diabetes, cardiovascular disease, and other chronic disorders. Bifidobacteria may help reduce the risk of these diseases by fermenting dietary fibre.
During the fermentation of dietary fibre, these bacteria produce compounds known as short-chain fatty acids (SCFAs), including acetate, butyrate and propionate, which play an important role in maintaining intestinal health and may also contribute to appetite regulation.
The role of bifidobacteria includes:
- Supplying host cells with essential nutrients;
- Fermentation of unused energy substances;
- Producing vitamins (vitamin K and folate) and short-chain fatty acids (SCFAs), including acetate, butyrate and propionate;
- Regulating fat storage;
- Maintenance and regulation of the host immune system (cytokine production);
- Prevention of colonization of pathogenic microorganisms through competitive exclusion.
Because of their important role in maintaining intestinal health, bifidobacteria are widely used as probiotics in food supplements to help improve the symptoms of irritable bowel syndrome (IBS), including bloating, abdominal cramps, abdominal pain, diarrhoea and constipation.
BUTYRIC ACID
Butyric acid is a short-chain fatty acid (SCFA), present in nature as a component of the fat fraction of milk and its derivatives. In humans, it is a physiological product formed in the large intestine as a result of fermentation of dietary fibre.
Butyrate plays an essential role in digestive health, providing energy to colon cells, meeting about 70% of their energy needs.
Increased intake of highly processed, low-fibre foods (“fast food”), rich in simple sugars, results in reduced butyrate production in the intestinal lumen.
Therefore, butyrate supplementation potentially represents a beneficial alternative.
INTESTINAL EFFECTS OF BUTYRIC ACID
- Main source of energy for colon epithelial cells.
- Maintains the colonic pH value, thereby promoting the absorption of nutrients and minerals while inhibiting the growth of potentially pathogenic bacteria.
- Stimulates the growth of normal colon epithelial cells.
- Improves intestinal barrier function by stimulating mucin formation, antimicrobial peptides, and tight junction proteins.
- Maintains a healthy intestinal mucosa.
- Has anti-inflammatory properties.
- Reduces oxidative stress in the colon.
Higher concentrations of butyric acid in the intestine improve intestinal barrier integrity, thereby reducing the permeability of harmful substances into the bloodstream.
Conversely, low concentrations of butyric acid increase intestinal permeability, allowing harmful substances to pass into the bloodstream, which may contribute to the development of disease.
CONDITIONS OF THE BODY ASSOCIATED WITH AN INCREASED NEED FOR BUTYRIC ACID
- Accelerated metabolism of intestinal epithelial cells under conditions of damage/inflammation;
- Increased energy expenditure of the body in pathological conditions;
- Stimulation of intestinal growth in “stressful” situations;
- Increased intestinal transit and enhanced secretion into the intestinal lumen (diarrhoea);
- Reduces endogenous production of butyric acid due to changes in bacterial flora in various pathological conditions.
References:
1. Introduction to the human gut microbiota Elizabeth Thursby and Nathalie Juge, The Gut Health and Food Safety Programme, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, U.K.
2. Butyric acid, Timothy J. Wiegand, in Reference Module in Biomedical Sciences, 2023.
3. The effect of probiotics on functional constipation in adults, Double-blind, randomized, placebo-controlled study, Fabiana Cristina Rosa Mitelmão, MSc, Cristiane de Cassia Bergamaschi, PhD, Marli Gerenutti, PhD, Karin Hächel, MD, Marcus Tolentino Silva, PhD, Victor M. Balcão, PhD, and Marta Maria Duarte Carvalho Vila.
4. Role of gut microbiota in functional constipation, Shengsheng Zhang1, Ruixin Wang, Danyan Li, Luqing Zhao, and Lixin Zhu, 1 Digestive Disease Center, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, P. R. China; and 2 Department of Colorectal Surgery, Guangdong Institute of Gastroenterology, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, P. R. China.
5. Cross-feeding between bifidobacteria and butyrate-producing colon bacteria explains bifidobacterial competitiveness, butyrate production, and gas production Luc De Vuyst, Frédéric Leroy.
6. Dynamics of Human Gut Microbiota and Short-Chain Fatty Acids in Response to Dietary Interventions with Three Fermentable Fibers Nielson T. Baxtera, Alexander W. Schmidta, Arvind Venkataramana, Kwi S. Kima, Clive Waldrona, Thomas M. Schmidthttps.