Maintaining healthy skin requires not only a skin care regimen that balances the skin microbiome, but also a sun exposure schedule that is tailored to the skin and microbiome.
Just as UV radiation is essential for vitamin D production in the skin, but can also cause skin ageing and skin cancer, the right amount of UV is also essential for balancing the skin microbiome.
One basis for the onset of rosacea is an inflammatory reaction against factors released by the skin microbiome, particularly Staphylococcus epidermidis and Demodex mites. UV radiation is one of the most commonly described triggers of rosacea. It causes skin cells to release inflammatory mediators. These in turn stimulate immune cells to react to factors of the skin microbiome, among others, with an inflammatory response. Therefore a strict sun protection is the cornerstone of management of rosacea.
The bacterium Staphylococcus aureus is not only a trigger in eczema, but the exotoxins released also have a disease-maintaining effect. People with eczema can observe an improvement in their skin appearance under photochemotherapy. This is probably due to the fact that UV radiation reduces the number of S. aureus on the skin and thus takes an important disease-causing factor out of play. Properly dosed UV radiation can therefore have a positive effect on the microbiome and skin health in eczema.