Last Updated on February 11, 2026 by MASSAGE Magazine
Lavender and rosemary essential oils may support the body’s defense against oxidative stress, according to research conducted in Japan.
For massage therapists who incorporate aromatherapy into sessions, this study provides insight into the physiological effects of inhaling certain essential oils. The research focused on free radical scavenging activity (FRSA), one of the body’s systems for defending against oxidative stress, which is associated with processes such as inflammation, aging and carcinogenesis.
The study, titled “Smelling lavender and rosemary increases free radical scavenging activity and decreases cortisol level in saliva,” was published in Psychiatry Research (Feb. 6, 2007, Vol. 150, No. 1, pp. 89–96).
What Is Oxidative Stress and Free Radical Scavenging Activity?
Oxidative stress refers to degenerative activity in the body caused by free radicals.
Free radicals are unstable molecules that can damage cells. The body uses several defense systems to manage them. One of these systems is free radical scavenging activity, or FRSA, which helps neutralize free radicals and reduce potential biological damage.
Researchers in this study used salivary cortisol as an indicator related to FRSA and stress response.
How Was the Aromatherapy Study Conducted?
Twenty-two healthy volunteers participated in the experiment.
Each subject sniffed one of the following for five minutes:
- Lavender essential oil diluted in odorless propylene glycol
- Rosemary essential oil diluted in odorless propylene glycol
- Odorless propylene glycol alone, which served as the control
The essential oils were tested at two concentrations:
- A low concentration diluted 1,000 times
- A high concentration diluted 10 times
Saliva samples were collected immediately before the aroma exposure to establish baseline levels, and immediately afterward to measure physiologically active substances.
What Did Researchers Measure in the Saliva?
Researchers analyzed saliva for:
- Cortisol
- Secretory immunoglobulin A (sIgA)
- Alpha-amylase activity, a digestive enzyme
These markers were examined because they are associated with stress and immune response and were found to correlate with aroma-induced FRSA.
What Were the Results?
The findings showed that free radical scavenging activity appeared to increase under certain conditions.
FRSA increased:
- With low concentrations of lavender
- With high concentrations of rosemary
At the same time, both lavender and rosemary stimulation decreased cortisol levels.
A significant inverse correlation was observed between FRSA values and cortisol levels with each concentration of rosemary stimulation. In other words, as FRSA increased, cortisol decreased.
No significant changes were observed in sIgA or alpha-amylase activity.
How Do Lavender and Rosemary Differ in the Nervous System?
Lavender is widely believed to stimulate the parasympathetic nervous system and support relaxation.
Rosemary, on the other hand, is known to stimulate the sympathetic nervous system, which is associated with alertness, memorization and concentration.
Interestingly, this study suggests that FRSA may be increased through both sympathetic and parasympathetic nervous system activation, depending on the essential oil used.
The authors concluded, “The results of our study on saliva suggest that aroma stimulations with lavender and rosemary may protect the body from oxidative stress by decreasing cortisol and potentiating FRSA.”
What Does This Mean for Massage Therapists Using Aromatherapy?
For therapists who integrate lavender or rosemary into sessions, this research adds another layer to the conversation.
Lavender may be chosen for relaxation-based work, while rosemary may be used in sessions focused on mental clarity or alertness. According to this study, both may influence stress markers and free radical defense systems in measurable ways.
It is important to remember that this study involved short-term aroma exposure in healthy volunteers. Still, the findings suggest that aromatherapy may influence physiological processes related to stress and oxidative balance.
For massage therapists, that reinforces what many already observe: scent is not just an accessory to bodywork. It can play a meaningful role in shaping the client’s overall physiological response to a session.