Humans are not solitary beings – we are walking biotopes. Our bodies harbour more bacteria, fungi, and viruses than they have human cells. This community of microorganisms, the microbiome, is far more than a passive cohabitant: it is an active health partner that co-determines immune function, metabolism, and even brain function.
Prof. Dr. Jörg Spitz explains how modern medicine long underestimated the microbiome. Only in the past two decades has research revealed that the gut microbiome plays a decisive role in regulating the immune system – approximately 70 percent of all immune cells reside in the gut. A healthy microbiome protects against chronic inflammation, allergies, and autoimmune diseases.
The gut-brain axis is one of the most fascinating research areas in modern medicine. Via the vagus nerve and the enteric nervous system – the "abdominal brain" with its roughly 100 million nerve cells – gut and brain communicate bidirectionally. Bacteria in the gut produce neurotransmitters such as serotonin, dopamine, and GABA, which influence our mood, sleep behaviour, and cognitive performance.
What harms the microbiome? Prof. Dr. Spitz highlights how antibiotics, processed foods, sugar, chronic stress, and lack of exercise reduce microbial diversity. Dysbiosis – an imbalance of the microbiome – is linked to diseases including diabetes, obesity, depression, Crohn's disease, and even Parkinson's disease.
What promotes a healthy microbiome? A fibre-rich diet, fermented foods like sauerkraut and yoghurt, exercise in nature, reduction of antibiotic exposure, and sufficient sleep – all are factors that strengthen microbial diversity. Prof. Dr. Spitz integrates microbiome knowledge into his comprehensive view of preventive medicine.