Getting a tan on holiday can make you ‘more vulnerable to infections’

Sunshine breaks are bad for the skin – and make people more vulnerable to infections, a new study warns. Researchers have shown that getting a holiday tan has a negative impact on the short-term diversity and composition of the skin’s bacterial make-up.

They explained that our skin, the largest organ of the human body, is home to a huge range of bacteria, fungi, and viruses – microorganisms that compose the skin microbiota. One of the key functions of the microbial populations, which are organised in complex community structures, is to protect against infections and disease.

The research team said that prolonged exposure to Ultraviolet radiation (UVR) is associated with damage to DNA in skin cells, inflammation, and premature skin ageing. But people still continue to take sun-seeking holidays.

University of Manchester researchers set out to examine the effects of sun-seeking on the skin microbiota composition of holidaymakers. Principal investigator Dr Abigail Langton said: “We show in a cohort of holidaymakers that their sun exposure behaviour significantly affects the diversity and composition of their skin microbiota.

“We have demonstrated that the development of a tan is associated with lower proteobacteria abundance immediately post-holiday. However, the microbiota of all holidaymakers was recovered a few weeks after they stopped spending extended time periods in the sun.”

Prior to holidays to sunny destinations, which lasted at least seven days, the researchers analysed participants’ skin. The skin microbiota is largely made up of three bacterial communities on the surface: Actinobacteria, Proteobacteria, and Firmicutes.

On day one, day 28, and day 84 after the holiday, participants’ skin microbiota was assessed again. Each holidaymaker was also assigned a group based on individual tanning response.

Eight out of 21 participants, who picked up a tan while on holiday, were deemed ‘seekers.’ The ‘tanned’ group was made up of seven people who already had a tan at departure and kept it throughout their holiday.

Those two groups were classified as ‘sun-seekers.’ The remaining six participants were deemed ‘avoiders’ as their skin tone was the same pre- and post-holiday.

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Study first author Dr Thomas Willmott said: “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 decreased skin microbiota diversity,”

But he said that despite the rapid reduction of proteobacteria and the accompanying shift in skin microbiota diversity, the bacterial community structure had recovered 28 days after individuals had returned from their trip. Dr Willmott added: “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.”

Dr Langton 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.”

The research team, whose findings were published in the journal Frontiers in Aging, say that what might be more concerning is the rapid alteration of microbiota diversity, which has been linked to disease. For example, a decrease in skin bacterial richness has been previously linked with dermatitis.

Fluctuation in proteobacteria diversity specifically has been associated with skin problems such as eczema and psoriasis. The researchers say future studies should examine why proteobacteria seem to be particularly sensitive to UVR and how that change in diversity impacts skin health in the longer term.

Dr Langton added: “Ideally, such studies will aim to increase the number of participants to allow further insights.”