Love to get your skin tanned on a beach trip? Beware, it may have a significant effect on your skin's microbiota composition, according to a study.

Skin, the largest organ of the human body, is home to a vast array of bacteria, fungi and viruses -- microorganisms that compose the skin microbiota and protect against pathogens

Prolonged exposure to ultraviolet radiation (UVR) is associated with damage to DNA in skin cells, inflammation and premature skin ageing, yet intentional sun-seeking behaviours remain common.

Researchers at the University of Manchester, the UK, showed that sun exposure behaviour significantly affects the diversity and composition of skin microbiota.

"However, the microbiota of all holidaymakers recovered a few weeks after they stopped spending extended time periods in the sun," said Abigail Langton, principal investigator from the varsity.

The skin microbiota is largely made up of three bacterial communities on the surface: Actinobacteria, Proteobacteria and Firmicutes.

The study, published in the journal Frontiers in Aging, demonstrated that the development of a tan is associated with lower Proteobacteria levels immediately post-holiday. 

The team analysed 21 participants' skin prior to vacations to sunny destinations, which lasted at least seven days. 

"This study was performed in real-life holidaymakers and provides important insights into how sun exposure resulting in a tanning response -- even over a relatively short sunny period -- can lead to an acute reduction in Proteobacteria abundance, which decreases skin microbiota diversity," said Thomas Willmott, the study's first author and researcher at the University of Manchester.

Despite the rapid reduction of Proteobacteria and the accompanying shift in skin microbiota diversity, the bacterial community structure recovered 28 days after individuals had returned from vacation. 

"This indicates that UV exposure on holiday has an acute effect on the skin microbiota, but recovery is relatively rapid once the person returns to a less sunny climate," Willmott said.

"Proteobacteria dominate the skin microbiota. Accordingly, it is not surprising that there would be rapid recovery of the microbiota to re-establish optimal functioning conditions for the skin," Langton said. 

The authors state that what might be more concerning is the rapid alteration of microbiota diversity, which has been linked to disease states.

A decrease in skin bacterial richness, for example, has been previously associated with dermatitis. Fluctuation in Proteobacteria diversity specifically has been associated with skin problems like eczema and psoriasis.

Future studies should examine why Proteobacteria seem to be particularly sensitive to UVR and how this change in diversity impacts skin health in the longer term, the researchers noted.