This project focuses on an omnipresent and understudied skin disorder: dandruff and seborrheic dermatitis (SD). Dandruff is a skin disorder that mainly disturbs the scalp, resulting in skin flaking and itchiness. SD also includes visible inflammation on other sebaceous rich skin regions. The high prevalence and significant impact on patient’s quality of life urges the need for a better understanding of the disease etiology and better alternatives for current short-term treatments. Several skin disorders (f.i. psoriasis) have an altered skin microbiome, surprisingly these skin conditions are also associated with an altered gut microbiome (gut-skin axis). SD has been linked and can be caused by an inflammatory immune response to Malassezia species that are responsible for an increased free fatty acid production on the skin. However, the link between gut dysbiosis and dandruff/SD has been controversial. This project anticipates a better understanding of the interplay between the skin and gut microbiome, the metabolome, the immunological response, the metadata together with the severity of the skin disease. An integrated multi-omics analysis should unravel important metabolic pathways, key disease biomarkers (microbiome/ metabolome) and key immune markers that are associated with SD/dandruff and the disease severity. This project aims to alleviate the skin conditions through skin bacteriotherapy and create novel industrial opportunities.