Dilrukshi et al.
Journal of Physiological Anthropology(2024) 43:3
https://doi.org/10.1186/s40101-023-00352-1

Journal of
Physiological Anthropology

Open Access

ORIGINAL ARTICLE

Alleviation of acute stress response by black
pepper aroma administration
E. A. Chayani Dilrukshi1,2, Yuta Nishiyama1, Kanetoshi Ito3 and Shusaku Nomura1*   

Abstract
Background Black pepper is one of the most popular spices globally. As black pepper essential oil has not yet beenused in the context of aromatherapy, this study examined the effect of black pepper aroma on cardiac and peripheral autonomic nervous system (ANS) activity under stressful conditions using an olfactometer to administer aroma
in a precise and controlled manner to ensure reproducibility.
Methods A within-participant design experiment was conducted with 20 male university students who performed
a 30-min calculation task as a short-term stressor under three aroma conditions: black pepper, ginger, and dipropylene glycol (DPG) (scentless air as a control). Each aroma was sporadically delivered (first 20 s of each 1-min interval)
with the olfactometer during the task. Electrocardiograms and skin conductance level (SCL) were measured to evaluate ANS’s physiological acute stress response. Subjective evaluations for the given stressful task and impressions
on the types of aromas were assessed.
Results The physiological acute stress response induced by the short-term stressor, which is characterized
by the enhancement of the heart rate (HR) and SCL and decreases in the heart rate variability (HRV), was suppressedwith black pepper: the increase in HR and reduction in HRV from the baseline were 38.9% (p = 0.048 when comparedwith DPG) and 32.9% smaller (p = 0.002 for multiple comparisons) than those in DPG, respectively, and the increaseof SCL was 15.5% smaller (p = 0.005 for multiple comparisons) than that in ginger. However, there was no significant
difference in subjective scores among the conditions.
Conclusion Although black pepper is a stimulative agent, the study findings showed that black pepper aroma alleviated the physiological acute stress response, which can be beneficial in aromatherapy under stressful conditions.
Keywords Black pepper, Heart rate, Heart rate variability, Skin conductance level, Acute stress response, Autonomic
nervous system activity*Correspondence:
Shusaku Nomura
nomura@vos.nagaokaut.ac.jp
1
Graduate School of Engineering, Nagaoka University of Technology,
Nagaoka, Niigata 940‑2188, Japan2
Department of Industrial Management, Faculty of Applied Sciences,
Wayamba University of Sri Lanka, Kuliyapitiya 60200, Sri Lanka
3
Corporate Research & Development, Takasago International
Corporation, Hiratsuka, Kanagawa 254‑0073, Japan

BackgroundAromatherapy has gained popularity globally in complementary and alternative medicine. It uses different typesof essential oils, and various psychological and physiological effects are expected from these aromas. Previous
studies on aromatherapy have reported reduced anxiety
with lavender [1, 2], orange [3–6], sandalwood [7], citrus
ginger [8], Hiba [1], and Melissa officinalis (lemon balm)
extract [9]; relieved stress with lemon [10], peppermint[11], black tea [12], green tea [13] and blended essential
oil with sandalwood and lavender [14]; improved sleep
quality with lavender [2, 15, 16] and Rosa damascene [17];© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to theoriginal author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images orother third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory
regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of thislicence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

induced physiological relaxation with Hinoki cypress leafoil [18], and increased memory performance with lavender, rosemary [19], and ginger [20].
Ginger (Zingiber officinale Roscoe), a popular edible
spice, has also been reported in previous studies to show
various psychophysiological benefits and pain relief.
Inhalation of ginger essential oil has demonstrated positive effects on nausea and vomiting severities [21–23]
and ginger oil massage has been effective in relieving
chronic low back pain [24] and moderate-to-severe knee
pain [25] in older adults, while ginger extract showed
positive efficacy in pain relief and improved functionality
in patients with moderate knee osteoarthritis [26]. Moreover, inhalation of citrus ginger during sleep enhanced
sympathetic nervous system (SNS) activity upon awakening and alleviated psychological tension and anxiety [8].
In black pepper (Piper nigrum L.), known as the ‘kingof spices’, the flavor comes from the compound piperine[27]. Black pepper has functional uses in culinary, perfumery, and traditional medicine [28, 29]. Few studies
have assessed the efficacy of its essential oils in medical use, and an aromatic essential oil cream comprising
black pepper, marjoram, lavender, and peppermint has
been reported to improve pain tolerance and neck pain[30]. Additionally, studies have suggested that inhaled
black pepper oil may improve postural stability in older
adults by reducing the velocities of posture adjustments[31] and the sensory and reflexive motor movement ofswallowing via activation of the right insular cortex inpatients with dysphagia [32, 33]. Two studies reported
the effect of topically applied black pepper essential oil
for enhancing vein visibility in patients, thus aiding easy
intravenous catheter insertion [34, 35].
In contrast to previous studies, which primarily evaluated the stimulant properties of black pepper aroma for
specific clinical outcomes, this research delves into unexplored research areas by investigating the therapeuticpotential of black pepper essential oil within the context
of aromatherapy. Notably, this study extends beyond
assessing arousal efficiency to comprehensively explore
therapeutic benefits, considering the stimulative sensation of black pepper as a food ingredient and its positive
efficacies. These positive effects include pain relief and its
potent warming effect [36], similar to other stimulative
spices such as mustard and ginger, which are thought toincrease blood flow, attributing to attenuation of peripheral SNS activity [37, 38].
Focusing on the therapeutic efficiency of black pepper essential oil, we employed a psychological loading
test methodology in this study. In studies assessing
physiological stress responses to short-term stressors,
electrocardiograms (ECG) and skin conductance levels(SCL) are frequently used as physiological measures.

Page 2 of 10

Thoma et al. (2013) observed a subsequent change inheart rate (HR) while listening to music in a stressful
situation [39]. Enhanced parasympathetic nervous system (PSNS) activity indicated by the high frequency(HF) component of heart rate variability (HRV) was
observed with Zen meditation [40], soothing music[41], and forest bathing [42]. Additionally, research on
using citrus mint-flavored mouthwash revealed a significant reduction in SCL during the recovery period
following a calculation task [43]. Hence, employing
physiological measures such as ECG and SCL to evaluate the acute stress response may yield promising
results.
Controlling the concentration and duration of aroma
administration has been a challenge in many previous
studies, and the outcomes of those studies might havebeen affected by olfactory fatigue. Most of those studies
adopted conventional methods for administering aroma,
including aroma diffusers [44–46] or impregnating materials with aroma [4]. Therefore, to prevent olfactory
fatigue, this study used a customized olfactometer, which
precisely controlled the concentration and duration ofaroma inhalation to ensure experiment reproducibility.
Thus, this study aimed to investigate the alleviating
efficacy of black pepper in aromatherapy under stressful
conditions by determining the acute physiological stressresponses in the autonomic nervous system (ANS) in awell-controlled laboratory setting using an olfactometer.
We hypothesized that black pepper aroma would alleviate physiological stress responses to a short-term cognitive stressor, specifically suppressing the increase in HR
and SCL and the decrease in HF compared to the scentless condition.

Methods
Participants

The study comprised 20 healthy male university students with a mean ± standard deviation (SD) age of 21.5
± 0.87 years (the range of age is from 24 to 20 years) anda mean ± SD body mass index (BMI) of 22.8 ± 3.2 kg/
m2 (the range of BMI is form 18.2 kg/m2 to 29.1 kg/m2).
None of the participants have any previous record of illnesses related to olfactory function. Pre-screening was
conducted before the experiment for each participant tocheck the normality of their sense of odor using a simple olfactory testing kit (Open Essence, FUJIFILM Wako
Pure Chemical Corporation, Japan).
The study was conducted following the ethical principles of the Helsinki Declaration of 1975, as revised in2000 (5), and informed consent was obtained from allparticipants. The study design was approved by the ethics
committee of the Nagaoka University of Technology.

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

Experimental procedure
Experimental protocol

Figure 1 shows the experimental protocol. Each participant was instructed to rest for 10 min (R1), perform a
30-min calculation task to induce cognitive stress (T),and undergo a 15-min recovery period (R2). The Kraepelin test, commonly conducted in laboratory studies, wasused as the cognitive stressor in this study [5, 47]. It is
performed by displaying a single one-digit addition exercise on a computer screen for 30 min. Although the task
was simple, it entailed a high degree of focus and concentration. Furthermore, the participants were guided
to complete the task as quickly and precisely as possible.
Each participant experienced three aroma conditions,
including black pepper, ginger, and scentless air, on three
separate days. The order of aroma conditions was counterbalanced. All experiments were conducted in an aircontrolled laboratory with a mean (± SD) temperature of
25.1 ± 0.8 °C and humidity of 58.9% ± 6.4%.
Aroma essential oils

Black pepper essential oil (Takasago International Corporation, Kanagawa, Japan) was used as the main component, and ginger essential oil (Takasago International
Corporation, Kanagawa, Japan) was employed as a typical “stimulant” and a reference aroma. Major constituents in black pepper and ginger essential oils are given
in Table 1. A scentless solvent, dipropylene glycol (DPG),
was used as the control stimulus in the study.
Aroma administration

Black pepper, ginger aroma, or DPG was sporadicallyadministered (first 20 s of each 1-min interval) througha cannula placed under the nostrils and connected to acustom-built olfactometer (Tatsumi Kagaku Co. Ltd,
Kanazawa, Japan). The scentless air flowed into the aroma

Page 3 of 10

Table 1 Major constituents of essential oils used in the study
Essential oil

Constituent(%)

Black pepper

β-Caryophyllene

35.1

Limonene

15.0

α-Pinene

10.3

β-Pinene

10.2

Gingerδ-3-Carene

8.5

α-Zingiberene

36.5

β-Sesquiphellandrene

14.1(3E,6E)-α-Farnesene

8.1

β-Bisabolene

7.3α-Curcumene

5.6

at a rate of 1.5 L/min to volatilize the essential oil. The
volatilized essential oil was conveyed to the cannula byregulating the timing and volume using an electromagnetic valve, which was precisely controlled on the orderof microseconds following the pre-programmed timing.
This timing was programmed through our developed
interface on the personal computer to achieve sporadic
delivery of the aroma. Olfactory fatigue of participants
was prevented by the sporadic delivery of aromas [5, 47].
Measurements
Physiological measurements

During the experiment (R1-T-R2), an ECG was recorded
using a bio-amplifier (MP150, BIOPAC Systems Inc., CA)
at a sampling rate of 500 Hz and a resolution of 16-bit
to analyze the HR and HRV. Electrodes were placed
underneath the right clavicle and on the lower left abdomen following the Lead II placement protocol for ECG
measurements (ECG sensor: TSD155C, BIOPAC Systems
Inc.). After the acquisition, the signals were filtered using
a 35 Hz low-pass filter, a 50 Hz notch filter, and a 0.05 Hz

Fig. 1 Schematic presentation of the experimental protocol. Participants performed a 30-min calculation task as a short-term stressor under threearoma conditions: black pepper, ginger, and dipropylene glycol (DPG) (scentless air as a control). Each participant experienced three aroma
conditions on three separate days (within-participant design). The order of aroma conditions was counterbalancedDilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

low-cut filter. The HF component (range 0.15–0.40 Hz) of
HRV was identified as a measure of cardiac PSNS activity[18, 48, 49]. Additionally, the SCL, as a measure of SNS,was recorded using the same bio-amplifier at a sampling
rate of 500 Hz with 16-bit resolution. The sensors wereplaced on the palmar side of the middle phalanx of theindex and ring fingers of the participant’s non-dominant
hand (SCL sensor: TSD203, BIOPAC Systems Inc.). A
low-pass filter at 1.0 Hz was used after the signal acquisition. All analyses were performed using the software(AcqKnowledge 4.1, BIOPAC Systems Inc.) dedicated tothe bio-amplifier.
Psychological measurements

Subjective measures were assessed using the visual
analog scale (VAS) and a scent questionnaire, as commonly used in previous studies [5, 50]. VAS, a calibrated
line with two endpoints of 0 and 100% [12], comprising seven items; ‘Nervousness’, ‘Effort’, ‘Concentration’,‘Fatigue’, ‘Irritation, ‘Boredom’, and ‘Fed-up’ were given
to the participants at the end of R1, T, and R2 (Fig. 1).
The participants rated their perception of each of theseven items on their respective points in less than 10 s.
Furthermore, a scent questionnaire was provided to ratethe ‘Comfort’, ‘Strength’, ‘Preference’, and ‘Awakening’ ofeach aroma condition using a 7-point Likert scale (1–7;
strongly disagree–strongly agree) at the end of T.
Statistical analysis

The raw values of HR, HF, and SCL were standardized(z-score) considering each participant and condition,

Page 4 of 10

owing to the significant individual variations, and all thevalues were baseline-corrected regarding the mean value
at R1. After conducting the Shapiro-Wilk test, paired t
tests were performed to compare subjective and objective parameters within and among the conditions if thedatasets could be considered normally distributed; otherwise, Wilcoxon signed-rank tests were performed as well.
Bonferroni corrections were used for multiple comparisons among the conditions. Even if no significant difference was found in multiple comparisons, if the statistical
test results “before” applying the Bonferroni correction(i.e., results of the pairwise test) had a p value < 0.05, it
was noted as informative information. To explore therelationship between subjective impressions of aroma
and physiological measures, Spearman’s rank correlation
coefficient was determined. The statistical significancelevel for p was set at 0.05. Statistical analysis was performed using R software (version 4.2.2., R Foundation for
Statistical Computing, Vienna, Austria).

Results
Heart rate and heart rate variability

Figures 2a and 3a show the change in HR and HF components of HRV for the three conditions. The results
showed an enhancement of HR and a decrease in HF
during the task (T) compared to R1 (ps < 0.01) regardlessof the conditions, which indicated a typical acute stressresponse of the SNS and PSNS [47, 51].
Figures 2b and 3b illustrate the mean HR and HF values during the task. The results showed that black pepper and ginger maintained lower levels in HR than in

Fig. 2 a Changes in heart rate (HR) (mean ± SEM per 2.5 min) and b mean HR value during the task (T) (mean ± SEM), *p < 0.05, #p < 0.05
before multiple comparisonsDilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

Page 5 of 10

Fig. 3 a Changes in high-frequency (HF) component of heart rate variability (HRV) (mean ± SEM per 2.5 min) and b mean HF component value
during the task (T) (mean ± SEM), *p < 0.05, **p < 0.01

DPG and relatively higher levels in HF than in DPG. The
acute stress-induced enhancement in HR during the task
was marginally smaller in black pepper (38.9% smaller
than that in DPG, t19 = 2.11, p = 0.048; note that it wasdetermined by a paired comparison with DPG) and wassignificantly smaller in ginger (46.8% smaller than thatin DPG, t19 = 2.89, p = 0.028) than in DPG. The acutestress-induced decrease in HF during the task was significantly smaller with black pepper (32.9% smaller than thatin DPG, t19 = 4.04, p = 0.002) and ginger (25.2% smaller
than that in DPG, t19 = 2.82, p = 0.033) than with DPG.

The smaller enhancement of HR and decrease in HF by
black pepper and ginger compared to DPG indicated the
suppression of acute stress response on cardiac SNS andPSNS by black pepper and ginger.
Skin conductance level

Figure 4a shows the changes in the SCL. For all three
conditions, SCL was enhanced during the task compared with R1 (ps < 0.001), which represented a typical acute stress response of peripheral SNS [50, 51].
According to the mean SCL values during the cognitiveFig. 4 a Changes in skin conductance level (SCL) (mean ± SEM per 2.5 min) and b mean value of SCL during task (T) (mean ± SEM), **p < 0.01

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

task, as shown in Fig. 4b, the enhancement in SCL during the task in black pepper was significantly smaller
than in ginger (15.5% smaller than that in ginger,
t19 = 3.63, p = 0.005). The SCL value of black pepper
remained at the lowest level through most of the T as
shown in Fig. 4a and was lower in mean value than thatof DPG, while it did not reach a significant level, representing a suppression of the peripheral SNS elevationby black pepper.

Table 2 Results of subjective impressions for each aroma
condition (7-point Likert scale)Condition
ComfortStrength

Preference

Awakening

Mean

(SD)

DPG

4.25

(1.02)

BLP

3.60(1.39)

GIN

4.20(1.24)

DPG

2.50 †, ‡(1.40)

BLP

4.45 †(0.94)

GIN

3.90 ‡(0.79)

DPG

4.25(1.12)

BLP

3.55(1.19)

GIN

4.10(1.17)

DPG

3.90(1.02)

BLP

4.80(1.32)

GIN

3.90(1.21)DPG dipropylene glycol, BLP black pepper, GIN ginger, SD standard deviation†, ‡p < 0.001, Bonferroni-corrected comparison between each condition

Page 6 of 10

Subjective impressions and VAS scores

Table 2 demonstrates the subjective impressions of eacharoma. All participants in this study could distinguishbetween the three conditions used: DPG, black pepper,and ginger. According to these subjective impressions,
black pepper and ginger were stronger than DPG (ps <0.001). There were no significant differences between theconditions for the other items.
In addition, significant positive and negative correlations were observed between ‘Strength’ and mean HR
during the task (n = 20, r = 0.51, p = 0.023) and between‘Awakening’ and mean HF during the task (n = 20, r =− 0.50, p = 0.025) in black pepper as shown in Fig. 5a,b respectively. There was no correlation between ‘Preference’ and ‘Comfort’ and any of the physiological measures for all aroma conditions.
Table 3 shows the VAS scores for R1, T, and R2. Regardless of the conditions, VAS scores indicated an increasein ‘Nervousness’, ‘Effort’, ‘Concentration’, ‘Fatigue’, ‘Irritation’, and ‘Fed-up’ and a decrease in ‘Boredom’ during T
compared to at R1. Therefore, the 30-min calculation task
employed in the study functioned as a short-term cognitive stressor similar to a previous study [47]; It should
be noted that, similar to other studies [5, 47], there wasno significant difference in task performance observed
between the aroma conditions. The scores for ‘Fed-up’ inblack pepper were significantly lower than those in DPG
during T (t19 = 2.63, p = 0.049). However, there were no
significant differences between the three conditions ineach period.

Fig. 5 a Correlations observed between ‘Strength’ and mean HR during the task and b Correlations observed between ‘Awakening’ and mean HF
during the task

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

Page 7 of 10

Table 3 Results of subjective measures (VAS scores) for each aroma condition
VAS score

Nervousness

EffortConcentration

Fatigue

Irritation

BoredomFed-upCondition

Rest (R1)

Task (T)Rest (R2)

Mean

(SD)

Mean

(SD)

Mean

(SD)

DPG

31.2

(22.6)

32.4(19.7)

25.5(18.4)

BLP

24.0(17.1)

41.4(20.1)

23.4(19.0)

GIN

24.1(19.4)

35.0(19.9)

20.3(16.6)

DPG

30.8(20.4)

50.7(22.7)

26.9(20.6)

BLP

25.7(19.5)

49.9(20.7)

24.7(21.7)

GIN

25.5(21.3)

49.8(23.0)

22.8(17.7)

DPG

40.6(22.7)

50.1(22.9)

31.8(21.0)

BLP

38.0(22.7)

53.4(24.8)

29.3(21.4)

GIN

35.2(23.9)

45.8(24.9)

30.5(24.6)

DPG

28.2(21.3)

51.0(23.7)

39.6(23.5)

BLP

22.4(18.8)

49.0(21.0)

41.8(22.1)

GIN

25.8(20.2)

51.2(21.6)

35.8(18.1)

DPG

20.2(19.5)

30.1(21.1)

22.2(17.9)

BLP

17.4(17.0)

26.6(17.6)

22.8(18.1)

GIN

18.9(16.7)

34.2(20.2)

17.9(15.8)

DPG

39.0(21.4)

28.3(20.6)

43.2(20.7)

BLP

39.1(21.3)

25.7(19.6)

43.5(19.1)

GIN

42.3(19.7)

27.0(18.2)

41.6(20.3)

DPG

25.1(21.7)

36.7 *(20.3)

30.2(23.7)

BLP

23.4(15.1)

30.0 *(17.4)

30.3(18.5)

GIN

25.4(17.9)

38.3(22.1)

28.7(18.0)*DPG dipropylene glycol, BLP black pepper, GIN ginger, VAS visual analog scale, SD standard deviation; p = 0.049, Bonferroni-corrected comparison between eachcondition

Discussion
This study evaluated the effects of black pepper aroma on
peripheral and cardiac ANS activity under stressful conditions using a customized olfactometer to ensure subsequent reproducibility. As for the results, the acute stressresponse in HF was suppressed in black pepper andginger compared with DPG, and that in SCL was suppressed in black pepper compared with ginger. There wasa marginal suppression of acute stress by black pepper
compared with DPG concerning HR. Regarding the subjective impressions of the participants, black pepper andginger were stronger than DPG, while there was no significant difference in psychological parameters between
the three conditions for the other items. Although black
pepper has been used as a preservative and stimulative
spice, our findings suggested that it has an alleviative
effect under stressful conditions.
The biological mechanism underlying these effects ofblack pepper aroma inhalation on ANS response remains
unclear. β-caryophyllene, the main component contained in the black pepper essential oil used in the study,
is found in many dietary condiments, including cloves,oregano, thyme, and cinnamon [52]. Although animalstudies have shown that β-caryophyllene may attenuate

hyperglycemia [53], its physiological effects have notbeen extensively studied. The pharmacological effects of
α- and β-pinene isomers have been extensively studied.
Previous research has shown they have critical pharmacological effects in animals, including antibacterial, antioxidant, and anti-inflammatory effects [54, 55]. However,the lack of research on human subjects makes it difficult to discuss physiological background concerning theresults of psychophysiological studies such as the present
study. On the other hand, one study on olfactory stimulation with limonene demonstrated enhanced HF and significantly lower HR in relaxing situations [56], providing
some insights into the physiological effects of limonene.
These effects may lead to the current study findings.
It is difficult to compare this study with previous
studies directly. This is because, to the best of ourknowledge, only a few studies have been conducted onblack pepper aroma. Although black pepper is a frequently utilized dietary condiment globally, several paststudies have investigated black pepper in the context
of pain relief. Ou et al. 2014 assessed the efficacy of anaromatic essential oil cream composed of black pepper, marjoram, lavender, and peppermint (2:2:1:1) onneck pain and reported improved pain tolerance andDilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

significant improvement in neck pain. SNS activity is
associated with the generation of pain [57, 58], and the
reduction of pain using aromatic essential oil cream canbe suggested as a suppression of SNS activity. The suppression of the cardiac and peripheral SNS response by
black pepper observed in our study is consistent withthese findings. Furthermore, there was no significant
difference in the subjective impressions between theconditions; this demonstrated the physiological effectsof black pepper, with no significant difference in psychological effects.
Generally, black pepper is believed to act as a stimulant
during consumption because of its spicy sensation, andthis stimulatory effect has been observed in several previous studies. The inhalation of black pepper oil resulted
in the improvement of reflexive swallowing movement inolder patients with dysphagia, which would help prevent
aspiration pneumonia [32, 33]. Black pepper aroma usedin smoking cessation programs stimulates respiratory
tract sensations, thereby reducing the level of craving for
nicotine and cigarettes [59]. The activation of SNS canwiden the bronchial passages and provide support for
inhalation, while PSNS stimulates swallowing and digestion [36]. The stimulative effect of black pepper has beenshown to affect the ANS response of the body in behavioral and clinical studies.
A positive correlation was observed between ‘Strength’and HR and a negative correlation between ‘Awakening’and HF in black pepper. This indicates a reasonable relationship between psychological state and physiologicalstate as ‘Strength’ and ‘Awakening’ connect to ‘Stimulative’ sensation in some sense. Specifically, the more a participant sensed black pepper as ‘Strong’, HR increased,
and the more a participant sensed it as ‘Awakening’, HF
was suppressed. In this sense, the black pepper remained
to be perceived as a stimulant. Thus, black pepper shouldhave both psychological and physiological effects (at least
stronger than those of ginger or DPG), and their relationship seemed reasonable (such as SNS activation followed by stimulative sensation). However, in the context
of stressful situations, the physiological alleviative effectdemonstrated in our study was remarkable and effective. Some studies have investigated the health benefitsof black pepper as a food ingredient and stimulative. In
contrast, few studies have identified the psychophysiological benefits of black pepper aroma inhalation. To
the best of our knowledge, there has not been a study
that demonstrated the positive efficacy of black pepper
essential oil under stressful situations. As black pepper isa readily available spice worldwide, the essential oil canbe consumed as a handy spice in the kitchen. Althoughsome people may prefer not to use it in their food, it canbe beneficial in aromatherapy.

Page 8 of 10

One of the limitations of this study was the inclusionof only male university students. The age range was narrow, 4 years, and those classified as obese by WHO criteria (BMI ≥ 30) [60] were not included. Including such ahomogeneous study population was intentional to avoid
discrepancies in the results. There are significant differences in human olfactory abilities with age [61, 62] andwomen generally outperform men in olfactory abilities[63]. Female hormonal imbalance during specific phasesof the menstrual cycle can affect olfaction and may resultin variations in SNS and PSNS activity [64–66]. Subjective impressions, including the preference for aroma,also vary depending on factors such as sex, age, ethnicity, or cultural exposure to specific odors [67, 68]. Even
though the study used a homogeneous sample to exclude
possible interferences, there is room for future researchby introducing a heterogeneous study population, which
would enable the exploration of the differences between
subgroups within the population. The Kraepelin test is a
widely used stressor in the laboratory setting [47]. However, employing various stressors other than the Kraepelin test may be a better solution to avoid substantial
limitations. The study faced technical limitations in precisely determining aroma concentration; it is a technicalconstraint common to aroma research. These challenges
should be noted when interpreting the study results. This
study did not assess the effects of black pepper when it
is consumed. Hence, future research should focus on thesystematic administration of black pepper essential oil ina similar or different experimental background to assistin further exploration of the benefits of black pepper
aroma.

Conclusion
This study investigated the psychophysiological effectsof black pepper aroma on peripheral and cardiac ANS
activities under short-term cognitive stress. The experimental results suggested that inhalation of black pepper
aroma suppressed the acute stress response in the ANS.
Although black pepper is a stimulative agent, the study
findings suggested that it can function as an alleviative
agent in stressful situations. Since black pepper is one of
the most popular spices in the world, black pepper essential oil can be used in aromatherapy to alleviate stressunder stressful conditions.
Abbreviations
ANS	Autonomic nervous system
DPG	Dipropylene glycol
SCL	Skin conductance levelHR	Heart rate
HF	High frequency
HRV	Heart rate variability
PSNS	Parasympathetic nervous system

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

Page 9 of 10

SNS	Sympathetic nervous system
SD	Standard deviation

9.

Acknowledgements
We would like to thank Takumi Tsunoda, Shu Sato, Yusuke Mon-nai, and Yuki
Okawa for their assistance in data collection in this study.

10.

Authors’ contributions
EACD: formal analysis, visualization, writing—original draft. YN: formal analysis,
validation, writing—review and editing. KI: resources, software, funding acquisition. SN: conceptualization, methodology, investigation, writing—review
and editing, project administration. All authors read and approved the final
manuscript.
Funding
This study was partially funded by Takasago International Corporation and the
Nagaoka University of Technology.
Availability of data and materials
The datasets supporting the conclusions of this article are available in the OSF
repository, https://​osf.​io/​bu5e3/?​view_​only=​cdf4f​f c558​a344b​39d44​d79de​
94df1​ae.

11.
12.
13.
14.
15.
16.

Declarations
Ethics approval and consent to participate
The study was conducted in accordance with the ethical principles of theHelsinki Declaration of 1975, as revised in 2000 (5), and informed consent was
obtained from all participants. The study design was approved by the ethics
committee of the Nagaoka University of Technology.
Consent for publication
All authors have provided their consent for publication.
Competing interests
The authors declare that they have no competing interests.

17.
18.
19.
20.
21.

Received: 26 August 2023 Accepted: 19 December 2023
22.

23.
References
1. Itai T, Amayasu H, Kuribayashi M, Kawamura N, Okada M, Momose A,
et al. Psychological effects of aromatherapy on chronic hemodialysis
patients. Psychiatry Clin Neurosci. 2000;54:393–7.
2. Karadag E, Samancioglu S, Ozden D, Bakir E. Effects of aromatherapy on
sleep quality and anxiety of patients. Nurs Crit Care. 2017;22:105–12.
3. Goes TC, Antunes FD, Alves PB, Teixeira-Silva F. Effect of sweet orange
aroma on experimental anxiety in humans. J Altern Complement Med.
2012;18:798–804.
4. Rashidi-Fakari F, Tabatabaeichehr M, Mortazavi H. The effect of
aromatherapy by essential oil of orange on anxiety during labor: arandomized clinical trial. Iran J Nurs Midwifery Res. 2015;20:661–4.
5. Lekamge S, Nakachi M, Sato S, Ito K, Nomura S. Alleviation of the acutestress response following mild orange essential oil administration. IEEJ
Trans Electr Electron Eng. 2017;12:S158–63.
6. Igarashi M, Ikei H, Song C, Miyazaki Y. Effects of olfactory stimulation
with rose and orange oil on prefrontal cortex activity. Complement
Ther Med. 2014;22:1027–31.
7. Kyle G. Evaluating the effectiveness of aromatherapy in reducing levelsof anxiety in palliative care patients: results of a pilot study. Complement Ther Clin Pract. 2006;12:148–55.
8. Jiang F, Kobayashi T, Ichihashi T, Ito K, Nomura S. The effect of citrus
ginger aroma on heart rate and salivary cortisol level during sleep athome. IEEJ Trans Electr Electron Eng. 2019;14:623–9.

24.

25.

26.

27.
28.
29.
30.

Motahareh B, Shahin H, Masoud M, Tabandeh S. The effects of Melissa
officinalis leaf extract on anxiety among patients undergoing orthopedic
surgeries. J Herb Med. 2022;31:100532.
Fukumoto S, Morishita A, Furutachi K, Terashima T, Nakayama T, Yokogoshi
H. Effect of flavour components in lemon essential oil on physical or
psychological stress. Stress Health. 2008;24:3–12.
Toda M, Morimoto K. Evaluation of effects of lavender and peppermint
aromatherapy using sensitive salivary endocrinological stress markers.
Stress Health. 2011;27:430–5.
Yoto A, Fukui N, Kaneda C, Torita S, Goto K, Nanjo F, et al. Black tea aroma
inhibited increase of salivary chromogranin-A after arithmetic tasks. J
Physiol Anthropol. 2018;37:1–6.
Yoto A, Murao S, Nakamura Y, Yokogoshi H. Intake of green tea inhibited
increase of salivary chromogranin A after mental task stress loads. J
Physiol Anthropol. 2014;33:1–8.
Lin PH, Lin YP, Chen KL, Yang SY, Shih YH, Wang PY. Effect of aromatherapy
on autonomic nervous system regulation with treadmill exercise-induced
stress among adolescents. PLoS One. 2021;16:1–13.
Keshavarz Afshar M, Moghadam ZB, Taghizadeh Z, Bekhradi R, Montazeri
A, Mokhtari P. Lavender fragrance essential oil and the quality of sleep in
postpartum women. Iran Red Crescent Med J. 2015;17:e25880.
Hamzeh S, Safari-Faramani R, Khatony A. Effects of aromatherapy withlavender and peppermint essential oils on the sleep quality of cancer
patients: a randomized controlled trial. Evid Based Complement Alternat
Med. 2020;2020:7480204.
Hajibagheri A, Babaii A, Adib-Hajbaghery M. Effect of Rosa damascene
aromatherapy on sleep quality in cardiac patients: a randomized controlled trial. Complement Ther Clin Pract. 2014;20:159–63.
Ikei H, Song C, Miyazaki Y. Physiological effect of olfactory stimulation
by Hinoki cypress (Chamaecyparis obtusa) leaf oil. J Physiol Anthropol.
2015;34:1–7.
Filiptsova OV, Gazzavi-Rogozina LV, Timoshyna IA, Naboka OI, YeV D,
Ochkur AV. The effect of the essential oils of lavender and rosemary on
the human short-term memory. Alexandria J Med. 2018;54:41–4.
Choi JG, Kim SY, Jeong M, Oh MS. Pharmacotherapeutic potential of ginger and its compounds in age-related neurological disorders. Pharmacol
Ther. 2018;182:56–69.
Karaman S, Karaman T, Tapar H, Dogru S, Suren M. A randomized placebocontrolled study of aromatherapy for the treatment of postoperative
nausea and vomiting. Complement Ther Med. 2019;42:417–21.
Lua PL, Salihah N, Mazlan N. Effects of inhaled ginger aromatherapy
on chemotherapy-induced nausea and vomiting and health-related
quality of life in women with breast cancer. Complement Ther Med.
2015;23:396–404.
Adib-Hajbaghery M, Hosseini FS. Investigating the effects of inhaling ginger essence on post-nephrectomy nausea and vomiting. Complement
Ther Med. 2015;23:827–31.
Sritoomma N, Moyle W, Cooke M, O’Dwyer S. The effectiveness of Swedish massage with aromatic ginger oil in treating chronic low back painin older adults: a randomized controlled trial. Complement Ther Med.
2014;22:26–33.
Yip YB, Tam ACY. An experimental study on the effectiveness of massage
with aromatic ginger and orange essential oil for moderate-to-severe
knee pain among the elderly in Hong Kong. Complement Ther Med.
2008;16:131–8.
Kordi Yoosefinejad A, Zarshenas MM, Sadeghi Mazidi J, Tahmasbi M.
Phonophoresis of semisolid formulation of Zingiber officinale Roscoehydroalcoholic extract improves quality of life in patients with moderateknee osteoarthritis: a randomized clinical trial. J Herb Med. 2021;29.
Ahmad N, Fazal H, Abbasi BH, Farooq S, Ali M, Khan MA. Biological roleof Piper nigrum L. (Black pepper): a review. Asian Pac. J Trop Biomed.
2012;2:S1945–53.
Srinivasan K. Role of spices beyond food flavoring: nutraceuticals withmultiple health effects. Food Rev Int. 2005;21:167–88.
De Souza EL, Stamford TLM, De Oliveira LE, Trajano VN, Barbosa Filho JM.
Antimicrobial effectiveness of spices: an approach for use in food conservation systems. Braz Arch Biol Technol. 2005;48:549–58.
Ou MC, Lee YF, Li CC, Wu SK. The effectiveness of essential oils for patientswith neck pain: a randomized controlled study. J Altern Complement
Med. 2014;20:771–9.

Dilrukshi et al. Journal of Physiological Anthropology(2024) 43:3

31. Freeman S, Ebihara S, Ebihara T, Niu K, Kohzuki M, Arai H, et al. Olfactorystimuli and enhanced postural stability in older adults. Gait Posture.
2009;29:658–60.
32. Ebihara S, Kohzuki M, Sumi Y, Ebihara T. Sensory stimulation to improveswallowing reflex and prevent aspiration pneumonia in elderly dysphagic
people. J Pharmacol Sci. 2011;115:99–104.
33. Ebihara T, Ebihara S, Maruyama M, Kobayashi M, Itou A, Arai H, et al. A
randomized trial of olfactory stimulation using black pepper oil in older
people with swallowing dysfunction. J Am Geriatr Soc. 2006;54:1401–6.
34. Eren H, Turkmen AS, Aslan A. Effect of topical application of black pepper
essential oil on peripheral intravenous catheter insertion: a randomized
controlled study. Explore (NY). 2021;18:457–62.
35. Kristiniak S, Harpel J, Breckenridge DM, Buckle J. Black pepper essential
oil to enhance intravenous catheter insertion in patients with poor vein
visibility: a controlled study. J Altern Complement Med. 2012;18:1003–7.
36. Winklewski PJ, Radkowski M, Demkow U. Cross-talk between the inflammatory response, sympathetic activation and pulmonary infection in theischemic stroke. J Neuroinflammation. 2014;11:4–11.
37. Vagedes J, Kuderer S, Vagedes K, Hiller S, Beissner F, Szőke H, et al. Increasing warmth in oncological patients: a randomized controlled cross-overpilot trial examining the efficacy of mustard and ginger footbaths. Integr
Cancer Ther. 2021;20:15347354211058448.
38. Vagedes J, Helmert E, Kuderer S, Müller V, Voege P, Szőke H, et al. Effects
of footbaths with mustard, ginger, or warm water only on objective
and subjective warmth distribution in healthy subjects: a randomized
controlled trial. Complement Ther Med. 2018;41:287–94.
39. Thoma MV, La Marca R, Brönnimann R, Finkel L, Ehlert U, Nater UM. The
effect of music on the human stress response. PLoS One. 2013;8:e70156.
40. Murata T, Takahashi T, Hamada T, Omori M, Kosaka H, Yoshida H, et al. Individual trait anxiety levels characterizing the properties of zen meditation.
Neuropsychobiology. 2004;50:189–94.
41. Iwanaga M, Kobayashi A, Kawasaki C. Heart rate variability with repetitive
exposure to music. Biol Psychol. 2005;70:61–6.
42. Lee J, Park B-J, Tsunetsugu Y, Ohira T, Kagawa T, Miyazaki Y. Effect of forest
bathing on physiological and psychological responses in young Japanesemale subjects. Public Health. 2011;125:93–100.
43. Ishikawa M, Okawa Y, Wakabayashi E, Hirono A, Oshima Y, Nomura S. Physiological effects of using citrus mint flavored mouthwash. Transactions ofJapan Society of Kansei Engineering; 2023. p. 22. TJSKE-D-22-00034
44. Chang KM, Shen CW. Aromatherapy benefits autonomic nervous systemregulation for elementary school faculty in Taiwan. Evid Based Complement Alternat Med. 2011;2011:946537.
45. Matsumoto T, Asakura H, Hayashi T. Effects of olfactory stimulation fromthe fragrance of the Japanese citrus fruit yuzu (Citrus junos Sieb. ex
Tanaka) on mood states and salivary chromogranin A as an endocrinologic stress marker. J Altern Complement Med. 2014;20:500–6.
46. Nagata Y, Miyashita Y, Mori M. The influence of olfactory stimulation by
essential oils on salivary alpha-amylase activity and state anxiety level.
Jpn J Complement Altern Med. 2013;10:39–43.
47. Nomura S, Maeyama K, Ito K. Enhancement of autonomic stress response
and reduction of subjective stress by lavender inhalation during a shortterm calculation task. Adv Biomed Eng. 2016;5:7–12.
48. McCraty R, Shaffer F. Heart rate variability: New perspectives on physiological mechanisms, assessment of self-regulatory capacity, and healthrisk. Glob Adv Health Med. 2015;4(1):46–61.
49. Kobayashi H, Ishibashi K, Noguchi H. Heart rate variability; an index formonitoring and analyzing human autonomic activities. J Physiol Anthropol Appl Hum Sci. 1999;18:53–9.
50. Lekamge S, Nakachi M, Sato S, Ito K, Nomura S. Psychophysiologicaleffects of aroma inhalation during a short-term cognitive stressor:
a preliminary study using eight different aromas. Int J Affect Eng.
2017;16:213–20.
51. Berntson G, Bigger JRJT, Eckberge W, Grossman P, Kaufmann P, Malik M.
Heart rate variability: origins, methods, and interpretive caveats. Psychophysiology. 1997;34:623–48.
52. Chaturvedi D, Dwivedi PK. Recent developments on the antidiabetic
sesquiterpene lactones and their semisynthetic analogues. In: Discovery
and Development of Antidiabetic Agents from Natural Products. Elsevier;2017. p. 185–207.

Page 10 of 10

53. Basha RH, Sankaranarayanan C. β-Caryophyllene, a natural sesquiterpene
lactone attenuates hyperglycemia mediated oxidative and inflammatorystress in experimental diabetic rats. Chem Biol Interact. 2016;245:50–8.
54. Salehi B, Upadhyay S, Erdogan Orhan I, Kumar Jugran ALD, Jayaweera SA,
Dias D, et al. Therapeutic potential of α- and β-Pinene: a miracle gift ofnature. Biomolecules. 2019;9:738.
55. Cheng W-W, Lin C-T, Chu F-H, Chang S-T, Wang S-Y. Neuropharmacological activities of phytoncide released from Cryptomeria japonica. J Wood
Sci. 2009;55:27–31.
56. Joung D, Song C, Ikei H, Igarashi M, Koizumi H, Park B, et al. Physiologicaland psychological effects of olfactory stimulation with D-limonene. Adv
Hortic Sci. 2014;28:90–4.
57. Burton AR, Fazalbhoy A, Macefield VG. Sympathetic responses to noxious
stimulation of muscle and skin. Front Neurol. 2016;7:109.
58. Schlereth T, Birklein F. The sympathetic nervous system and pain. NeuroMolecular Med. 2008;10:141–7.
59. Rose JE, Behm FM. Inhalation of vapor from black pepper extract reduces
smoking withdrawal symptoms. Drug Alcohol Depend. 1994;34:225–9.
60. World Health Organization. Obesity and overweight. https://​www.​who.​
int/​news-​room/​fact-​sheets/​detail/​obesi​ty-​and-​overw​eight. 2021.
61. Sorokowska A, Schriever VA, Gudziol V, Hummel C, Hähner A, Iannilli E,
et al. Changes of olfactory abilities in relation to age: odor identificationin more than 1400 people aged 4 to 80 years. Eur Arch Otorhinolaryngol.
2015;272:1937–44.
62. Kim KS, Nam HJ. Autonomic nervous function in final year Oriental medical students in Korea: Influence of gender, age and academic performance. Stress Health. 2010;26:430–6.
63. Sorokowski P, Karwowski M, Misiak M, Marczak MK, Dziekan M, Hummel
T, et al. Sex differences in human olfaction: a meta-analysis. Front Psychol.
2019;10:1–9.
64. Gómez-Amor J, Martínez-Selva JM, Román F, Zamora S. Electrodermal
activity in menstrual cycle phases: a comparison of within- and betweensubjects designs. Int J Psychophysiol. 1990;9:39–47.
65. Saperova EV, Filippova I. Heart rate variability during different phases of
menstrual cycle. The FASEB J. 2022;36.
66. Garavaglia L, Gulich D, Defeo MM, Mailland JT, Irurzun IM. The effectof age on the heart rate variability of healthy subjects. PLoS One.
2021;16:1–20.
67. Fitzgerald M, Culbert T, Finkelstein M, Green M, Liu M. The effect of gender and ethnicity on children’s attitudes and preferences for essential oils:
a follow up study. Explore (NY). 2010;6:172.
68. Fitzgerald M, Culbert T, Finkelstein M, Green M, Johnson A, Chen S. The
effect of gender and ethnicity on children’s attitudes and preferences foressential oils: a pilot study. Explore: J Sci Heal. 2007;3:378–85.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Ready to submit your research ? Choose BMC and benefit from:• fast, convenient online submission• thorough peer review by experienced researchers in your field• rapid publication on acceptance• support for research data, including large and complex data types• gold Open Access which fosters wider collaboration and increased citations• maximum visibility for your research: over 100M website views per year
At BMC, research is always in progress.
Learn more biomedcentral.com/submissions