A recent extensive review published in Nature Reviews Microbiology highlights that our skin is home to around 1,000 species of microorganisms including bacteria, fungi, and viruses that play crucial roles in maintaining skin health, preventing pathogenic infections, and regulating immune responses. One of the most prominent of these microorganisms is Staphylococcus epidermidis, which produces ceramides that are vital for protecting the skin barrier. A decrease in this beneficial bacterium can lead to dry and vulnerable skin, which is particularly evident in patients with conditions like atopic dermatitis and psoriasis where harmful bacteria such as Staphylococcus aureus thrive instead.

Recent findings have revealed a significant connection often referred to as the 'gut-skin axis', suggesting that the health of the skin microbiome is not solely determined by local factors on the skin, but begins with health conditions in the gut. According to a 2025 review in Microbes, beneficial gut bacteria break down dietary fiber to produce butyrate, a short-chain fatty acid that travels through the bloodstream and promotes the activation of mitochondria in skin cells, which in turn boosts the production of skin barrier substances. Animal studies have shown that increasing butyrate levels through a high-fiber diet leads to marked improvements in symptoms of atopic dermatitis.

Mitochondria play a crucial role in this process, as skin cells in psoriasis patients show damage to mitochondrial DNA that triggers severe inflammatory responses. In contrast, excessive reactive oxygen species production within mitochondria in atopic conditions inflicts direct damage to skin cells. A weakened mitochondrial response can also compromise regulatory T cells, identified as a key component in immune regulation, which may lead to an increase in inflammatory immune cells when their numbers dwindle, exacerbating skin conditions.