The human microbiome is home to a community of microorganisms. Research has shown that a diverse gut microbiome is a healthier microbiome – it makes a vital contribution to our health. Around a third of the population are experiencing gut microbial imbalance (dysbiosis). This state is characterised by altered interactions between symbiotic microbes and their host. These could result in incurable immune-mediated diseases for which current therapeutics only address symptom alleviation. The EU-funded Homo.symbiosus project plans to develop novel gut ecology-based therapeutic approaches to restore man-microbe symbiosis.