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Marie Jourdan (Dermatologist)
On vacation, we tend to want to be exposed to the sun intensely and often during the hottest hours. But beware, this intense exposure, even if it is short-lived, can damage the skin’s microbiome. The explanations of Marie Jourdan, dermatologist.
The largest organ in the human body, the skin is covered with a microbiome, a veritable ecosystem made up of bacteria, fungi and other micro-organisms. Its complex balance helps protect us from pathogens.
Preserving your tan or your microbiome?
In this study, the English researchers investigated how sun exposure could affect the skin microbiome and in particular its composition. They analyzed the skin of 21 volunteers before they left for a vacation of at least a week.
“At that time, the skin microbiota of these volunteers is largely composed of three bacterial communities on the surface: Actinobacteria, Proteobacteria and Firmicutes” note the scientists. On the first day, the 28th day and the 84th day after the holidays, their skin microbiota was again evaluated.
In addition to this analysis, each holidaymaker was assessed on their return, based on their “tanning habits”. Eight of the 21 participants were categorized as seeking a tan, seven participants were already tanned and retained their skin tone when they returned, and the final six volunteers were categorized as sun avoidant, their skin tone being the same before and after their stay.
A change in the composition of the skin microbiome
Result : “We show in a cohort of vacationers that their sun exposure habits significantly affect the diversity and composition of their skin microbiota (…) We demonstrated that the development of a tan is associated with a lower abundance of proteobacteria immediately after the holidays” explains Dr. Abigail Langton, senior researcher at the University of Manchester and author of the study.
A temporary disruption whose effects remain to be clarified
However, this change is temporary. Indeed, despite the rapid reduction of proteobacteria and the change in the diversity of skin microbiota, the bacterial community returned to the initial stage 28 days after the volunteers returned from vacation. “This indicates that vacation UV exposure has an acute effect on skin microbiota, but recovery is relatively rapid once the person returns to a less sunny climate.” add the scientists.
The authors point out that the rapid alteration of the diversity of microbiota (a decrease in the bacterial richness of the skin) has already been associated with dermatitis; just as the fluctuation in the diversity of proteobacteria has been associated with skin problems such as eczema and psoriasis.
The point of view of Dr Marie Jourdan, dermatologist and member of the Doctissimo expert committee
“The skin microbiome is an important research subject in dermatology, in perpetual evolution. For several years, we have been profiling the microbiome of people affected by certain skin pathologies such as acne or eczema, in order to be able to develop new treatments”. “This study underlines that UV rays have a negative role on this skin microbiome. It can however be noted that the number of participants remains quite small. But above all, if this impact exists, it is less important than the impact of UV rays on the cells of the skin, which is beyond doubt and which is truly dramatic!” “The main reason for protection against ultraviolet rays remains prevention of skin cancers, long before the disruption of the skin microbiome”.