For many, having a Christmas tree (typically a pine or fir tree) in the living room is a beloved holiday tradition, and the tradition may serve not only a spiritual role but also a health benefit.

A research team led by Thomas Loew, physician and director of the Department of Psychosomatic Medicine at University Hospital Regensburg in Regensburg, Germany, examined the measurable effects of pine scent and group singing on the immune system. “Since time immemorial, humans have developed rituals and habits that serve not only spiritual but also biological functions. This includes the custom of putting up a Christmas tree,” Loew said in a press release.

Christmas Tree Scent May Boost Immune Response

So does putting up a Christmas tree do more than please the eye — does the scent of pine needles make us happier or even directly influence the immune system? “Yes, we were able to find that many study participants showed a molecularly detectable positive reaction to the scent of the trees, which can be associated with an improvement in immune function,” explained Professor Loew, “and this is not just a psychological effect.”

Activation of Nasal Mucosa

Pine needles release essential oils that rapidly activate the defense system in the nasal mucosa. This process triggers the release of nitric oxide (NO), an important marker of immune response that can be easily measured in exhaled breath.

Interestingly, humming songs and melodies produced a similar effect, which also demonstrably increased NO release and thus activated immune function.

Study Methodology

In a randomized crossover design, 16 volunteers either inhaled fresh pine scent (from a freshly cut tree kept for approximately 24 hours in the test room) or hummed for 5 minutes; humming was used as a control as it is known to increase nasal fractional exhaled NO (FeNO) levels in minutes.

FeNO was measured immediately before and after the exposure and the control procedure. A simple subjective relaxation test was taken in parallel.

Results

Before-after comparisons revealed an impressive increase in NO concentrations; however, the results were not statistically significant, nor were intraindividual (pre-post) differences between the two groups (Wilcoxon test). Positive changes with the scent of the felled tree were observed in 44% of volunteers and with humming in 48%. Almost 70% of the study participants benefited from at least one of the two stimuli; only 25% showed no increase.

Singing and Smelling Together

“In our study, each of the two interventions — simply smelling the tree and humming melodies — led to an immediate improvement in immune function in over 40% of participants, though usually according to the principle of ‘either/or.’ In combination, around 70% showed increased immune function. Only about a quarter showed no measurable response. We could jokingly call these ‘Christmas Grinches,’” Loew summarized.

With a smile, one can conclude that the decorated Christmas tree and singing together around it might be more than just tradition; they apparently also benefit the immune system.

This article was translated from Coliquio.