JJCAM. 2013 March; 10 (1): 39–43【Short Communication】

The Influence of Olfactory Stimulation by Essential Oils on
Salivary Alpha-Amylase Activity and State Anxiety LevelYoshie NAGATA1,2,*, Yoko MIYASHITA2,3, Mitsuru MORI2
1

Department of Nursing, Hokkaido Bunkyo University School of Faculty of Human Science2

3

Department of Public Health, Sapporo Medical University School of Medicine

Department of Health and Nutrition, Hokkaido Bunkyo University School of Faculty of Human Science[ABSTRACT]
It is considered that olfactory stimulation by fragrance inhalation is one of the methods of relaxation. We examined the possibility by using
fragrance inhalation essential oils, such as
sweet orange oil and peppermint oil. We measured salivary alpha-amylase activity and stateanxiety levels in undergraduate students before
and after inhalation. Salivary alpha-amylase
activity levels have been utilized to assess thesympathetic nervous activity.
Our results indicate that both salivary alphaamylase activity and state anxiety levels are significantly reduced after fragrance inhalation of
the sweet orange oil. Consequently, ourresearch suggests that sweet orange essential
oil has a relaxation effect.
[Key words]
essential oil, salivary alpha-amylase activity,
State-Trait Anxiety Inventory-Form JYZ

INTRODUCTION
It has been shown that olfactory stimulation by fragrance
inhalation using essential oil exerts physiological effects. In
young healthy individuals, essential oil inhalation was found to
be an effective method of relaxation. As an indicator of relaxation, the low frequency (LF) and high frequency (HF) components of heart rate variability were used to quantify modulationof the sympathetic and parasympathetic systems1). Also, as
another indicator, salivary alpha-amylase activity levels havebeen utilized to evaluate sympathetic nervous activity. Previous studies have indicated that salivary alpha-amylase activity
levels rose in response to psychological and physical stress2,3).
Salivary alpha-amylase activity levels might reflect the acute
psychological response by fragrance inhalation4).
Few experimental studies have examined the physiologicaland psychological effects of essential oil fragrance inhalation.
It is expected that fragrance inhalation by using essential oil isan easy and noninvasive method to promote relaxation inhumans. Therefore, we investigated the relaxation effect offragrance inhalation on the sympathetic nervous activity by themeasuring of salivary-alpha amylase activity and state anxiety
level change by using the psychological index, the State Trait
Anxiety Inventory (STAI)5).

MATERIALS AND METHODS
1 Participants
Seventy-nine healthy undergraduate students (6 males and73 females) aged 19 to 21 years old, participated in our study.
All participants were informed about this study and consent
Accepted Date: October 12, 2012
* Department of Nursing, Hokkaido Bunkyo University School of Faculty of Human Science, 5–196–1, kogane-chuo, Eniwa-shi 061–1449,
Japan Tel: +81–123–29–8031 Fax: +81–123–34–0057 E-mail: ynagata@do-bunkyodai.ac.jp

Y. Nagata et al.

40

was obtained from each participant. This study was approved

trait-anxiety consist of 20 statements. Each answer has anby the Ethics Committee of Hokkaido Bunkyo University.

intensity range from 1 to 4, and a sum total classified individuals according to the anxiety scores: low (20–44 points), moderate (45–54 points), high (55–80 points), concerning both the

2 Methods
Participants were randomized to inhale sweet orange oil orstate and trait scores.

peppermint oil. Each participant was tested by control waterand sweet orange oil or peppermint oil at the same time on
separate days. Participants were unaware of what kind of

3 Statistical analysis
Paired t-test was used to examine differences between before and after fragrance inhalation in the state-anxiety. The

essential oil was applied.
A tissue paper containing 100 μl of water was used as theWilcoxon signed-rank tested differences between before andcontrol. Sweet orange (Citrus sinensis SIRIUS) oil and pepper-

after fragrance inhalation in salivary alpha-amylase activity

mint (Mentha piperita L SIRIUS) oil were used as essential oils

levels. Logarithmic-transformation was performed for levels offor fragrance inhalation. The main constituents of sweet orange

salivary alpha-amylase activity. The statistical significanceoil and peppermint oil were limonene (96.3%) and menthol

level was set at 0.05 of p-value. The analyses were performed(45.1%), respectively. For stimulation, 100 μl of the solution

with a commercially available statistical package (SPSS

was applied to a piece of absorbent tissue paper (5 × 5 cm), andVer. 16.0).

then placed under the participant’s nose to inhale the fragranceof the essential oil and control water. Participants inhaled theRESULTS

control and the fragrance of the essential oils for 1 min during

Change in salivary alpha-amylase activity levels induced byregular breathing.
Each participant took a seated position while inhaling thefragrance inhalation of sweet orange oil and peppermint oil

two samples, control water and essential oil. After inhalation ofwas measured. As shown in Fig. 1, comparison of measured

the control water, the salivary alpha-amylase activity and statelevels before and after inhalation of sweet orange oil decreased

anxiety levels were measured. Next, after the inhalation of thefrom 3.90 to 3.55 KU/L (median value: by logarithmic-essential oil, the salivary alpha-amylase activity and state anx-transformation) in salivary alpha-amylase activity (p < 0.05). In

iety level were measured again.

contrast, fragrance inhalation of peppermint oil did not showAs for the physiological parameters, the level of salivary

significant change.

alpha-amylase activity was measured by a Salivary Amylase

The “state” component of STAI-JYZ was used to evaluate

Monitor (Nipro Co., Japan), which consisted of a testing-strip,

before and after inhalation of sweet orange oil and peppermint

a salivary transcription device and an optical analyzer. Byoil. The state anxiety score decreased from 48.2 point to 41.2

adding maltose, a testing-strip is able to detect the salivary

point after fragrance inhalation of sweet orange oil. Thisactivity from 0 to 200 KU/L during a time of less than 150

change was statistically significant (p < 0.001). On the otherseconds, and a salivary transcription device controlled the reac-hand, the state anxiety score by inhalation of peppermint oil did7)

tion time of the enzyme . In order to evaluate the Salivary

not change after fragrance inhalation (Fig. 2).

Amylase Monitor, salivary alpha-amylase activity between 0and 200 KU/L, the calibration curve for the Salivary Amylase
Monitor obtained a coefficient of R2 value of 0.988 and acoefficient of variation of 10.2%8).

DISCUSSIONAs shown in Fig. 1 salivary alpha-amylase activity levels

The “state” component of the State-Trait Anxiety Inventory-

were significantly lower than before fragrance inhalation ofForm JYZ6) (STAI-JYZ) was used to evaluate each partici-

sweet orange oil. Previous studies have indicated that fragrance

pant’s anxiety levels before and after fragrance inhalation.

inhalation has an influence on salivary alpha-amylase activity

STAI-JYZ included of two distinctive self-assessment sub-or sympathetic nervous activity. It has been shown that salivary

scales: the state-anxiety, which refers to a transitory emotional

alpha-amylase activity decreased significantly by lavender oilstate or a state of stress and apprehension, and the trait-anxiety,inhalation4). In another study, fragrance inhalation of rose oil

which is able to assess relatively stable individual differences

resulted in a 30% decrease of adrenaline plasma concen-regarding anxiety tendencies. Both the state-anxiety and thetration9). On the other hand, fragrance inhalation of pepper oil

The influence of Olfactory Stimulation by Essential Oils

41

Fig. 1 Change of salivary alpha-amylase activity levels (logarithmic-transformation) before and after fragrance inhalation of essential oils.
*p < 0.05 (Wilcoxon signed-rank test).
sweet orange oil (n = 44), peppermint oil (n = 31)

Fig. 2 Change of state anxiety scores before and after fragrance inhalation of essential oils.
***p < 0.001 (paired t-test).
sweet orange oil (n = 39), peppermint oil (n = 31)

induced a 1.7-fold increase in plasma adrenalin concen9)

activity. Accordingly, it may be considered that the results fromtration . Furthermore, after fragrance inhalation of bergamot

this study showing salivary alpha-amylase activity levels

oil, there were significant decreases in blood pressure and heartdecrease after fragrance inhalation were caused by depressing

rate along with the ratio of the low frequency (LF) power tosympathetic nervous activity.

high frequency (HF) components of heart rate variability (LF/

From our results, the score of the state anxiety alsoHF) showing an increase in heart rate variability and HF power

decreased significantly from before fragrance inhalation of thepercentage10). These findings indicate that fragrance inhalation

sweet orange oil (Fig. 2). In other words, state anxiety levelof essential oil stimulates or depresses the sympathetic nervouschanged from moderate score (48.2) to a low score (41.2) afterY. Nagata et al.

42

1 min of fragrance inhalation of the sweet orange oil. It isconceivable that sweet orange oil might induce relaxation
through psychological effects and decrease sympathetic nervous system activity. In experimental study on Wister rats,

responses to psychological stress in men preparing for skydiving.
J Clin Endocrinol Metab 1997; 82(8): 2503–2509.
3) Skosnik PD, Chatterton RT Jr, Swisher T, et al. Modulation ofattentional inhibition by norepinephrine and cortisol after psychological stress. Int J Psychophysiol 2000; 36(1): 59–68.

anxiolytic effects were observed using sweet orange11). The

4) Yamaguchi M, Tahara Y, Kosaka S. Influence of concentration ofeffect of some essential oils, including sweet orange oil, andfragrances on salivary alpha-amylase. Int J Cosmet Sci 2009;

lavender oil were reported to reduce anxiety through use as12,13)

aromatherapy. In patients with breast cancer, the anxiety

scores reduced after massage of the neck, thorax, back, shoulders, arms, hand and upper legs using by sweet orange oil in theSTAI test14).

31(5): 391–395.
5) Kunikata H, Watanabe K, Miyoshi M, et al. The effects measurement of hand massage by the autonomic activity and psychological indicators. J Med Invest 2012; 59(1–2): 206–212.
6) Hidano S, Fukuhara M, Iwawaki M, et al. State-Trait Anxiety
Inventory-Form JYZ. Jitsumukyoiku-shuppan Co, Ltd. 2000: 23–

In contrast, our results show that there are no significant

26. Japanese.

differences before and after fragrance inhalation of peppermint7) Yamaguchi M, Kanemori T, Kanemaru M, et al. Performanceoil. Peppermint oil has been used to calm pruritus and relieve

evaluation of salivary amylase activity monitor. Biosens Bioelec-15)

irritation . Research indicates that peppermint oil and its
components, such as menthol, produce moderate inhibitory
activity against human pathogens16). Effects of peppermint oil
may be different from relaxation.

tron 2004; 20(3): 491–497.
8) Yamaguchi M, Hanawa N, Yoshida H. Evaluation of a novel
monitor for the sympathetic nervous system using salivary amylase activity. Medical Electronics and Biological Engineering
2007; 45: 161–168. Japanese.

Limitations of this study included that participants were only

9) Haze S, Sakai K, Gozu Y. Effects of fragrance inhalation onundergraduate students and a large majority were female stu-sympathetic activity in normal adults. Jpn J Pharmacol 2002;

dents. Various age groups and males will need to be studied in
the future. Also, another indicator of sympathetic nervous system activity will be required in future studies, such as LF/HF.
In conclusion, our findings suggest that fragrance inhalationof sweet orange oil may be utilized as a method of relaxation inundergraduate students.

90(3): 247–253.
10) Chang KM, Shen CW. Aromatherapy benefits autonomic nervoussystem regulation for elementary school faculty in taiwan. EvidBased Complement Alternat Med 2011; doi: 10. 1155/2011/946537.
11) Faturi CB, Leite JR, Alves PB, et al. Anxiolytic-like effect ofsweet orange aroma in Wistar rats. Prog Neuropsychopharmacol
Biol Psychiatry 2010; 34(4): 605–609.
12) Goes TC, Antunes FD, Alves PB, et al. Effect of sweet orange

ACKNOWLEDGEMENTS

aroma on experimental anxiety in humans. J Altern Complement
Med 2012; 18(8): 798–804.

The authors would like to thank the participants who cooper-13) McCaffrey R, Thomas DJ, Kinzelman AO. The effects of laven-ated in this study. This research was supported by a grant-in-aidder and rosemary essential oils on test-taking anxiety amongfrom Hokkaido Bunkyo University. The authors declare that
there are no conflicts of interest associated with this study.

graduate nursing students. Holist Nurs Pract 2009; 23(2): 88–93.
14) Imanishi J, Kuriyama H, Shigemori I, et al. Anxiolytic effect ofaromatherapy massage in patients with breast cancer. Evid BasedComplement Alternat Med 2009; 6(1): 123–128.

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The influence of Olfactory Stimulation by Essential Oils

43

要

旨精油嗅覚刺激による唾液 α-アミラーゼ活性と状態不安に及ぼす影響
長多好恵1,2，宮下洋子2,3，森満2

1

北海道文教大学人間科学部看護学科
札幌医科大学医学部公衆衛生学講座
3
北海道文教大学人間科学部健康栄養学科
2精油の香り吸入による嗅覚刺激は，リラクゼーションの方法の一つと考えられている．スウィートオレンジの嗅覚刺激後に，唾液 α-アミラーゼ活性と状態不安レベルは有意な低下を示した．ペパーミントでは，有意な変化はみられなかった．ある種の精油による嗅覚刺激によって，リラックス効果が得られる可能性が示唆された．
キーワード：精油，唾液 α-アミラーゼ活性，状態・特性不安検査（新版）