Do short-term bodily responses move in the same direction when people smell fragrances such as rose or grapefruit? In a 2002 study of healthy young women, an index calculated from blood-pressure fluctuations rose with four essential oils, including grapefruit, and fell with rose and patchouli.
A separate set of participants also underwent blood sampling, which showed a decrease in blood adrenaline after smelling rose. The study examined fragrance effects using two approaches, blood-pressure variability and substances in the blood, rather than relying on a single measurement.
Six essential oils compared with an odorless solvent
A total of 43 healthy women aged 22–25 participated, all of whom had experience using perfume in daily life. Twenty-one took part in the blood-pressure variability experiment, and a separate group of 22 participated in the blood-sampling experiment.
The blood-pressure experiment used six essential oils: black pepper, estragon, fennel, grapefruit, rose, and patchouli. Estragon is the herb also known as tarragon. Each person was randomly assigned three of the six oils. For each oil, the oil-containing sample and the odorless solvent TEC were compared in a randomized order. The design did not have all 21 participants smell all six oils.
The oils were dissolved in TEC at 2% by weight. A cotton ball containing a small amount was placed below the nose, and participants breathed normally. After a 30-minute rest, measurements were taken for 3 minutes at baseline and for 3 minutes during scent presentation. The 2% refers to the concentration of the liquid applied to the cotton, not the concentration in the air inhaled.
Looking at the size of fluctuations rather than blood pressure itself
The analysis examined the amplitude of the low-frequency component of fluctuations in systolic blood pressure, or SBP-LF. The authors used this as an indirect measure related to sympathetic nervous activity. The mean over 2 minutes during scent exposure was divided by the mean during the immediately preceding rest period and compared with the value under the odorless condition.
This relative index was significantly higher than in the odorless condition for black pepper, estragon, fennel, and grapefruit. In contrast, it was approximately 40% lower than in the odorless condition for rose and patchouli.
The important point is that what rose or fell was an index derived from low-frequency blood-pressure fluctuations. The findings do not mean that blood pressure itself fell by 40%, or that the researchers directly measured and suppressed the whole sympathetic nervous system by 40%. They show that responses in this physiological index differed by fragrance.
Blood sampling showed a decrease in adrenaline with rose
In the blood-sampling experiment, a separate group of 22 participants was divided into four groups, each receiving black pepper, grapefruit, rose, or odorless TEC for 7 minutes. Blood was drawn after a 30-minute rest and again after scent exposure to measure adrenaline, noradrenaline, and dopamine.
In the rose group, adrenaline concentration fell by approximately 30% from before exposure, a statistically significant decrease. With black pepper, there was a trend toward an increase to approximately 1.7 times the initial level, but p = 0.06 did not meet the conventional 5% significance threshold.
With grapefruit, adrenaline and noradrenaline increased numerically, but neither change was significant. No clear changes were reported for dopamine or the other measurements either.
The blood-sampling statistics compared before and after exposure within each group. They did not directly test whether the change in a fragrance group differed from the change in the odorless group. The before-and-after difference with rose was directionally consistent with the blood-pressure variability result, but it cannot be said that the two experiments definitively established exactly the same effect using different methods.
Both essential-oil composition and subjective experience need further study
The composition of the oils was also examined by GC-MS. Grapefruit consisted of 93.3% limonene; rose contained 27.7% citronellol and 15.0% geraniol, among other compounds; and patchouli contained 42.4% patchouli alcohol, among other components.
The authors considered the possibility that these compounds contributed to the different responses. However, the experiment compared mixtures in the form of essential oils, rather than testing limonene or citronellol individually. It is premature to assume that an oil’s name or its main ingredient predicts a consistent bodily response in every setting.
Several possible mechanisms were discussed, including emotions and memories evoked by scents and effects of the compounds themselves. Questionnaire responses reportedly indicated that all six scents were familiar and pleasant, but that alone does not exclude the influence of expectations or emotions.
The measurements were brief, lasting 3 or 7 minutes, and the participants were limited to young women. Adaptation and persistence with longer exposure, as well as replication in other age groups and sexes, remain questions. Applications to conditions such as hypertension or obesity were future possibilities discussed in the original paper, not treatment effects tested in this study.
Summary
A relative index derived from low-frequency blood-pressure fluctuations was higher than under an odorless condition with black pepper, estragon, fennel, and grapefruit, and lower with rose and patchouli. In a separate blood-sampling experiment, adrenaline decreased from before exposure with rose, while the increase with black pepper and the changes with grapefruit were not significant.
Short-term responses to fragrances differ depending on the essential oil and the measure used. Exploring these differences through two types of measurement was the study’s main contribution.
The paper lists all three authors as affiliated with Shiseido’s product development division. No separate funding or conflict-of-interest declaration was found.
Reference
Haze S, Sakai K, Gozu Y. Effects of Fragrance Inhalation on Sympathetic Activity in Normal Adults. Japanese Journal of Pharmacology. 2002;90(3):247–253. doi:10.1254/jjp.90.247
