Multiple tattoos could help the body fight off colds and other common infections, the new study suggests.
The study - published in the American Journal of Human Biology - found that this immune-boosting effect increases with multiple tattoos.
According to 2013 statistics from Pew Research Center, around 14% of Americans have at least one tattoo, and we spend around $1.65 billion a year on professional inkings.
While the majority of people do not experience any health complications after getting a tattoo, some individuals may experience an allergic reaction or skin infection.
But according to Dr. Christopher Lynn, associate professor of anthropology at the University of Alabama in Tuscaloosa, and colleagues, tattoos could also be beneficial to health, helping us to fight off colds and other common infections.
Multiple tattoos linked to a lower reduction in immunoglobulin A levels
To reach their findings, the team enrolled 29 individuals aged 18-47 who were receiving tattoos at one of three tattoo studies in Leeds and Tuscaloosa, AL, between May-December 2012.
The team collected saliva samples from participants both before and after their tattooing procedure, which they used to measure levels of immunoglobulin A - an antibody that acts as a first line of defense against common infections - and the "stress hormone" cortisol.
- Around 45 million adults in the US have at least one tattoo
- Adults aged 26-40 are most likely to have tattoos
- Around 17% of people say they feel some regret after getting a tattoo.
The researchers also collected information on how many tattoos each participant had, how many tattoo sessions they had encountered, the lifetime hours spent receiving a tattoo, how many years it had been since their first tattoo and the percentage of their body that was tattooed.
As expected, the team found that participants who were receiving a first tattoo showed a significant reduction in levels of immunoglobulin A - a response to a rise in cortisol that was triggered by the stress and pain of the tattooing procedure.
The team explains that, initially, getting a tattoo could make a person more susceptible to common infections.
"They don't just hurt while you get the tattoo, but they can exhaust you," says Dr. Lynn. "It's easier to get sick. You can catch a cold because your defenses are lowered from the stress of getting a tattoo."
However, the team found that people who had more tattoos showed less of a reduction in immunoglobulin A levels, which Dr. Lynn believes is down to increased immune system resilience that builds up with greater exposure to the stress of tattooing.
"After the stress response, your body returns to an equilibrium," says Dr. Lynn. "However, if you continue to stress your body over and over again, instead of returning to the same set point, it adjusts its internal set points and moves higher."
He explains that how the body responds to tattoos is similar to its response to exercise in unfit individuals; an initial workout may cause the muscles to hurt, but the pain reduces with more workouts, as the body becomes better at dealing with the stress of physical activity.
While the authors admit their study sample is small, they say the data offer important insight into the body's physiological response to tattooing.
Last year, a study reported by Medical News Today found that, for some people, infection, itching and swelling from tattoos can last for years.