Article by Ariadna Teixidó – Communications Manager of GENESIS Biomed

• The intestinal microbiota is a complex ecosystem unique to each individual.

• The study of the microbiota has gone from a focus limited to digestion to become a pillar of preventive and personalised medicine, opening up new therapeutic opportunities in multiple areas of health.

• Probiotics, prebiotics, postbiotics and synbiotics are emerging as therapeutic allies to modulate the microbiota and enhance its benefits.

• The gut-brain axis is consolidating as an emerging field, showing how the intestinal microbial balance influences cognitive functions, mood and mental well-being.

The understanding of the gut microbiota and its impact on human health has undergone a true scientific revolution in the last decade. The gut microbiota is a complex ecosystem composed of trillions of microorganisms, including bacteria, fungi, viruses and protozoa, which mainly inhabit the human digestive tract. This microbial community performs essential functions such as digestion and absorption of nutrients, synthesis of vitamins and regulation of the immune system.

Scientific interest in the gut microbiota dates back to the beginning of the 20th century, when the beneficial effects of lactic ferments in yoghurt were demonstrated and it was first suggested that certain bacteria could be allies of the body. For decades, research focused on their role in digestion and immunity, until the discovery of the so-called ‘second brain’ in the gut in the 1990s revealed their connection to the nervous system. With the development of next-generation sequencing techniques, it was possible to decipher the enormous microbial diversity that inhabits us, confirming that each person has a unique microbiota and that its imbalance is closely related to various diseases.

The microbiota is now recognised as a key element in multiple physiological processes, with particular emphasis on its influence on the gut-brain axis. This axis represents a bidirectional communication between the gut and the central nervous system. Numerous studies have shown that the gut microbiota can influence behaviour, mood and cognitive functions through immunological, endocrine and neural mechanisms.

It is in this context probiotics, live micro-organisms that when administered in adequate amounts, offer health benefits to the host, have emerged. Probiotic supplementation is emerging as a promising strategy not only to restore or maintain the balance of the gut microbiota, but also to improve digestive, immunological, metabolic and mental health. Its main clinical applications include:

• Digestive health: prevention and treatment of diarrhoea, irritable bowel syndrome and inflammatory bowel disease.
• Immunity: increase in IgA-producing cells, T-lymphocytes and NK cells, with reduction of recurrent respiratory infections.
• Metabolism: studies suggest that certain strains influence body weight, insulin sensitivity and lipid parameters.
• Women’s health: prevention of bacterial vaginosis and candidiasis by restoring the vaginal microbiota.
• Mental health: preliminary evidence suggests benefits for anxiety and mild to moderate depression.

In this context, other related compounds have emerged that complement and enhance the action of probiotics

• Prebiotics: non-digestible compounds, such as inulin or fructo-oligosaccharides, which selectively stimulate the growth of beneficial bacteria.
• Postbiotics: metabolic products or components derived from probiotics that can exert beneficial effects on the body even without the presence of live micro-organisms.
• Symbiotics: combine probiotics and prebiotics, enhancing the efficacy of both and promoting the establishment of the strains administered.

As a consequence of the importance of the environment, a diet rich in prebiotic fibres, polyphenols and fermented foods is shown to create a favourable environment for probiotics to exert their full therapeutic potential. This combined approach represents an even more effective way to address disturbances of the gut-brain axis and maintain the balance of the gut ecosystem.

In recent years, with the recognition of the gut-brain axis and its bidirectional sense, the concept of psychobiotics has emerged, defined as probiotics and prebiotics with a positive impact on mental health. Clinical trials suggest that regular consumption of certain psychobiotics can improve mood, decrease stress and reduce fatigue. However, the evidence is still heterogeneous and results vary between different population groups, underlining the need for more rigorous and personalised studies.

The role of the microbiota in human health has become one of the great scientific discoveries of recent years. Despite growing scientific evidence, key aspects such as the most effective specific strains, as well as the definition of optimal doses and the optimal duration of treatments still need to be further explored. The heterogeneity of clinical results underlines the need for rigorous and personalised studies to fully exploit the therapeutic potential of probiotics.