Intestinal Microbiota

The main functions of the microbiota include:

• Digestion and Nutrient Absorption:
  Intestinal bacteria help break down food components that the human body cannot fully digest on its own, such as certain fibres and complex carbohydrates. They produce short-chain fatty acids, which serve as an energy source for intestinal cells.
• Immune Modulation:
  The microbiota plays a vital role in the development and regulation of the immune system. It helps train the immune response to distinguish between harmless and harmful microbes and modulates inflammation.
• Protection Against Pathogenic Microorganisms:
  By colonising the intestine, bacteria form a barrier against pathogens. They compete for nutrients and binding sites on the intestinal lining, produce antimicrobial substances, and stimulate the production of mucins and antimicrobial peptides.
• Synthesis of Vitamins and Other Bioactive Molecules:
  Intestinal bacteria can synthesise essential vitamins such as vitamin K and certain B vitamins (e.g. biotin, folic acid).
• Metabolic Regulation:
  The microbiota influences the human metabolism and affects body weight, insulin sensitivity, and lipid profiles. It plays a role in extracting energy from food as well as in fat storage.
• Communication with the Nervous System:
  There exists bidirectional communication between the intestinal microbiota and the central nervous system, which is known as the gut-brain axis. This interaction can affect mood, behaviour, and neurological function.

Therefore, the health and balance of the microbiota are crucial for overall well-being and the prevention of disease. Factors such as diet, antibiotics, lifestyle, and the environment can all influence the microbiota.

The term microbiota refers to the entirety of microorganisms in a given habitat. The intestinal microbiota includes bacteria, fungi, viruses, and parasites. Microbiota analysis focuses specifically on bacterial populations. Since June 2016, GANZIMMUN has been offering a molecular biological method – Next-Generation Sequencing – in stool diagnostics. Previously only used in research, this technique allows for high-level detection of anaerobic bacteria that cannot be cultured via classical microbiological methods. This modern diagnostic method enables a more precise evaluation of the complex and individual impact of the microbiota on its host’s health.

Based on scientific studies, GANZIMMUN has developed a risk profile for microbiota-associated diseases. The report includes risk assessments for the following clinical pictures:

• Metabolic Diseases:
  Obesity, Type 2 Diabetes, cardiovascular disease, non-alcoholic fatty liver disease, alcoholic fatty liver disease
• Irritable Bowel Syndrome:
  IBS, leaky gut syndrome, histamine intolerance, food intolerances, small intestinal bacterial overgrowth (SIBO)
• Inflammatory Bowel Diseases:
  Chronic inflammatory bowel diseases, colorectal carcinoma, dysbiosis, reduced colonisation resistance, gastrointestinal infection susceptibility
• Autoimmune Diseases:
  Coeliac disease, rheumatoid arthritis, psoriasis, allergies/asthma, Type 1 Diabetes
• Neurological Diseases:
  Depression, chronic fatigue syndrome, autism spectrum disorder, Parkinson’s disease, Alzheimer’s disease

Crohn’s disease and ulcerative colitis are severe conditions for those affected. In Europe, these diseases are relatively common, with a prevalence of 1:198 for ulcerative colitis and 1:310 for Crohn’s disease. A defective mucosal barrier against commensal intestinal bacteria plays a key role in their pathogenesis. Both conditions are associated with reduced microbial diversity, which reflects a disrupted intestinal flora. This disruption results in low colonisation by bacteria such as Roseburia spp., Ruminococcus spp., Akkermansia muciniphila, Faecalibacterium prausnitzii and Odoribacter splanchnicus, which are capable of breaking down the existing mucus layer, but at the same time stimulate its rapid regeneration by producing short-chain fatty acids such as butyric acid (butyrate). In the absence of these short-chain fatty acids, which serve as an important energy source for colonocytes, proliferation, differentiation, and the production of mucins and defensins are significantly impaired, which allows for bacterial invasion. Typical key symptoms include diarrhoea, abdominal pain, and perianal bleeding, which occur recurrently.

Although the primary site of disease is the intestine, joints, eyes, and skin may also be affected.

Recent studies have examined the impact of the intestinal flora on neurological and psychiatric diseases such as autism, dementia, and mood disorders. Inflammatory processes have been identified as potential contributors to schizophrenia, depression, and bipolar disorder.

In the case of depression, potential causes considered to date have included neuropsychiatric disorders, immunological processes, genetic predisposition, and various environmental factors. The recently observed correlation with the intestinal microbiota is now being explored with increasing scientific interest. Clinical studies which characterise the intestinal microbiota have revealed an above-average prevalence of Alistipes from the Bacteroidetes phylum, as well as the genera Lactobacillus and Bifidobacterium, in patients with depression and anxiety symptoms.

Numerous studies have shown a correlation between intestinal flora and body weight, particularly the ratio of Firmicutes to Bacteroidetes. Measuring this ratio can provide insight into dietary habits and offer a starting point for nutritional interventions.

Firmicutes and Bacteroidetes make up over 90% of the human intestinal microbiota. Research shows that the Firmicutes/Bacteroidetes ratio in stool correlates with a person’s body weight. The general finding is: the lower the proportion of Firmicutes and the higher the proportion of Bacteroidetes, the lower the body weight, OR the higher the proportion of Firmicutes and the lower the proportion of Bacteroidetes, the higher the body weight.

Firmicutes help the body extract additional calories by fermenting complex carbohydrates (dietary fibre) and other undigested food components into short-chain carbohydrates and fatty acids.

It is possible to increase the proportion of Bacteroidetes through dietary changes, which reduces the abundance of Firmicutes and limits energy extraction from food. Prebiotics and probiotics are also helpful tools for achieving a favourable bacterial flora.

• Prebiotics are fibres or carbohydrates not digested by the human body but fermented by beneficial bacteria in the colon.
• Probiotics are live microorganisms that help maintain a healthy intestinal flora by displacing harmful bacteria, promoting the production of beneficial substances such as vitamins, supporting immune function, and strengthening the intestinal barrier.

Several mucin-degrading bacteria are part of the mucosa-associated microbiota in healthy individuals.

Faecalibacterium prausnitzii is a gram-negative, obligate anaerobic rod-shaped bacterium from the Firmicutes bacterial strain. It is one of the three most common anaerobic bacteria in the intestine and acts as a “peacekeeper” by reducing inflammatory processes. It has a beneficial effect on diseases such as Crohn’s disease and ulcerative colitis.

Akkermansia muciniphila is a gram-negative, obligate anaerobic bacterium that degrades mucin and supports the growth of F. prausnitzii via its metabolic by-products. High levels of Akkermansia have been shown to positively influence:

• Body weight
• Fat mass
• Reduction of metabolic endotoxaemia caused by bacterial lipopolysaccharides
• Reduction of adipose tissue inflammation
• Reduction of insulin resistance (Type 2 Diabetes)

The development, diversity, and stability of the intestinal microbiota are closely linked to one’s lifestyle and dietary habits. As such, the microbiota must be viewed as a reflection of lifestyle. Short-term dietary changes or probiotic supplementation alone will not bring lasting change.

A stable microbiota requires a long-term diet that is diverse, low in fat, rich in fibre, and high in phytochemicals. A microbiota-friendly diet should:

• Be rich in complex carbohydrates and fibre (e.g. from vegetables, whole grains, legumes, and fruit)
• Include phytochemicals: carotenoids (e.g. red and yellow fruit and vegetables), flavonoids (e.g. apples, grapes, green tea), glucosinolates (e.g. cabbage, radish, mustard, cress), sulphides (e.g. onions, chives, garlic)
• Contain reduced protein and fat
• Avoid refined carbohydrates (e.g. sugar, white flour products)
• Avoid additives (e.g. artificial flavours, colourants, sweeteners, and emulsifiers)