We want to know more about our readers. Tell us about yourself in
our short survey
for a chance to win a MacBook Air.
Research article
Open Access
The effect of inhalation of Citrus sinensis flowers and Mentha spicata leave essential oils on lung function and exercise performance: a quasi-experimental uncontrolled before-and-after study
Recently, there has been an increased interest in the effects of essential oils on athletic performances and other physiological effects. This study aimed to assess the effects of Citrus sinensis flower and Mentha spicata leaves essential oils inhalation in two different groups of athlete male students on their exercise performance and lung function.
Methods
Twenty physical education students volunteered to participate in the study. The subjects were randomly assigned into two groups: Mentha spicata and Citrus sinensis (ten participants each). One group was nebulized by Citrus sinensis flower oil and the other by Mentha spicata leaves oil in a concentration of (0.02 ml/kg of body mass) which was mixed with 2 ml of normal saline for 5 min before a 1500 m running tests. Lung function tests were measured using a spirometer for each student pre and post nebulization giving the same running distance pre and post oils inhalation.
Results
A lung function tests showed an improvement on the lung status for the students after inhaling of the oils. Interestingly, there was a significant increase in Forced Expiratory Volume in the first second and Forced Vital Capacity after inhalation for the both oils. Moreover significant reductions in the means of the running time were observed among these two groups. The normal spirometry results were 50 %, while after inhalation with M. spicata oil the ratio were 60 %.
Conclusion
Our findings support the effectiveness of M. spicata and C. sinensis essential oils on the exercise performance and respiratory function parameters. However, our conclusion and generalisability of our results should be interpreted with caution due to small sample size and lack of control groups, randomization or masking. We recommend further investigations to explain the mechanism of actions for these two essential oils on exercise performance and respiratory parameters.
In recent times, the world has witnessed an increase in the use of essential oils to treat diseases and to promote better health [1, 2]. The natural plant’s essential oils are widely used in medicine and pharmacy for many purposes due to their evidence based physiological and psychological effects [3, 4]. They are also considered one of the most important branches of Complementary and Alternative Medicine, which is called aromatherapy that focuses on the usage of essential oils for the treatment of various illnesses by using natural essential oils [5–8].
Essential oils can cleanse cellular receptor sites of medications, petrochemicals and other disruptors of intercellular communication and can chelate heavy metals and other toxins, helping to remove and flush them through the kidneys, lungs, sweat, colon and liver. In fact, they increase the body’s ability to absorb nutrients and vitamins [9–11].
Moreover, many of the essential oils are used in the pharmaceutical industry as an active ingredient in the pharmaceutical formulations such as Eucalyptus, Peppermint, Thyme, Anise, Fennel oils and many others or they are used in the pharmaceutical industry as excipients as well as most of the flavoring agents which are used to improve the odor and taste of drugs that are isolated from various plants containing essential oils [12–15].
In the last thirty years, a series of studies were conducted to evaluate the effects of essential oils smelling on the behaviors, creativity, mood and many other psychological and physiological effects [16–20]. In vapor forms in the folk medicine Citrus sinensis flower oil used as sedative and Mentha spicata leaves oil used as bronchodilator, for that our study aimed to investigate their effects on the lung function and to evaluate their effects on athletic performance [21, 22].
Citrus sinensis (L.), orange or sweet orange is a small tree in the Rutaceae family that originated in southern China and now cultivated worldwide in tropical, semi-tropical, and some warm temperate regions, and have become the most widely planted fruit tree in the world. The fragrant white flowers, produced singly or in cluster of up to 6 flowers, which are around 5 cm wide, with 5 petals and 20 to 25 yellow stamens [23]. The flowers oil consist mainly from sabinene, linalool, limonene and trans-nerolidol [24] and are used as an antimicrobial, stomachic, carminative and flavoring agent as well as orange flowers water used in Palestine as food [25, 26].
Mentha spicata L.(Spearmint) belongs to the family Lamiaceae and characterized by its leaves essential oil that is of great economic importance and being used widely in cosmetic, pharmaceutical and food industries [27–29]. The major constituents of M. spicata leaves essential oil are carvone, limonene, dihydrocarvone, 1,8-cineol, β-bourbonene, β-caryophyllene, myrcene and α-pinene and aromatherapists. This oil is used for its antispasmodic, local anesthetic, astringent, carminative, decongestant, digestive, diuretic and expectorant effects [30–32].
Lung function tests (LFTs) are usually measured using the spirometer [33]. The spirometer is used to differentiate between obstructive and restrictive diseases and assess the degree of associated changes [34, 35]. Such parameters include Forced Expiratory Volume in the first second (FEV1) and Forced Vital Capacity (FVC). The specificity and sensitivity of spirometry in the diagnosis of obstructive lung disease are reported as 84 and 92 %, respectively [36]. The FEV1 is the maximum air volume is exhaled with maximal effort in the first second from a position of full inspiration. The FEV1/FVC ratio is reduced in obstructive patterns, but it is normal or increased in restrictive patterns as both nominator and denominator proportionally change [37].
In the last thirty years some studies have been conducted to evaluate the odors and consumption of essential oils on physical and psychological activities. Most of these studies focused on peppermint plant but unfortunately and according to the best of authors’ knowledge there were no previous studies about M. spicata and C. sinensis oils inhalations on the lung function and/or the athletic performance.
Methods
Instrumentations
During this study, the following instruments were used: ultrasonic-microwave cooperative extractor/reactor (CW-2000, China), balance (Radw ag, AS 220/c/2, Poland), Philips respironics inhalators nebulizers (75644321, China) and Care-fusion spirometer (ME44QY 08563848, UK).
Collection and preparing plant materials
The leaves of M. spicata and C. sinensis flowers were collected during its flowering time from Tulkarem region (Palestine) during April, 2015. Botanical identification was carried out by Pharmacognosist Dr. Nidal Jaradat from the Pharmacognosy and Herbal Products Laboratory, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus. The identification process was conducted using live herbal specimens and photographs from books. Voucher specimens were deposited in the Pharmacognosy and Herbal Products Laboratory under the code numbers: Pharm-PCT-2774 for M. spicata and was Pharm-PCT-2775 for C. sinensis.
To extract volatile oil, the leaves of M. spicata and the flowers C. sinensis were separated carefully and then washed twice with distilled water.
Essential oils extraction
The essential oil of M. spicata leaves were extracted using a microwave oven as described by Jaradat, 2016 with some modifications [38]. The power of the microwave oven was set at 1000 W. Clevenger apparatus with a 1 L round-bottom flask containing 100 g of M. spicata leaves was placed inside the microwave oven. About 500 ml distilled water was then added into the flask containing the powder. The flask was then connected to Clevenger apparatus. Microwave distillation was carried out three times for 15 min each at 100 °C. The obtained volatile oil was collected into a clean beaker and chemically dried then the purified essential oil was weighed and stored in tightly-closed amber-colored bottles at −4 °C in the refrigerator. The same procedure was repeated for extraction of C. sinensis essential oil flowers.
Subjects and study design
Twenty male university students from the faculty of physical education at An-Najah National University in Nablus-Palestine volunteered and were randomly assigned into two different groups (10 participants each) to take part in the experiments using a non-randomized quasi-experimental uncontrolled before-and-after study design for each group. The study was single blind at the level of participants. One group (10 students) was nebulized with M. spicata oil, while the other group (10 students) was nebulized with C. sinensis flowers oil (0.02 ml/kg of body mass of each oil) mixed with 2 ml of normal saline 5 min before a 1500 m running test according to the method validated by Spencer and Gastin, 2001. Traditionally, it was thought that in the middle distance track running the relative energy system was 75 % aerobic and 22 % anaerobic and a 2–3 % of the energy coming from the creatine-phosphate system. But recently, the aerobic energy system contributes significantly to the energy supply during middle distance running and long sprint event. Moreover, the relative anaerobic and aerobic system contributions of the four events (200 m, 400 m, 800 m, and 1500 m). In the middle distance running such as 1500 m event depends on the aerobic 84 % and anaerobic energy system which is greater than it was traditionally thought, so during this event the need of oxygen increases with the event duration from 200 to 1500 m running race [39].
Moreover, the 1500 m distance was required to ensure the duration of effect of the oils (if any) as inhaled route of administration and the greater distances could have been taken into consideration if the interventions were given orally or by another route of administration, however, our estimation was that this distance could be representable of such route of administration given at the same time that the same group conducted the running pre and post intervention.
A washout period of three days (from Sunday to Wednesday) between pre and after test for each group was given to rule out any fatigue or significant impact on our results pre and post test. Lung function tests were measured using a spirometer for each student pre and post nebulization. The study was carried out in May, 2016.
Methodology
The subjects were familiarized with the spirometry. Lung function tests were measured using a spirometer for each student pre and post inhalations with M. spicata and C. sinensis oils. The specificity and sensitivity of spirometer in diagnosis of obstructive lung disease are reported as 84 and 92 %, respectively [40]. While in the diagnosis of restrictive lung disease, it has a sensitivity and specificity of 42.2 and 94.3 %, respectively [41]. FEV1 is the maximum air volume exhaled with maximal effort in the first second from a position of full inspiration. This value declines less severely with restrictive diseases than obstructive diseases. FVC, on the other hand, is the maximal air volume exhaled with maximal effort from a position of full inspiration [42], and is reduced by an airflow obstruction and ventilation restriction, which results from lung-exterior factors such as skeletal pains or intrinsic lung disease, especially restrictive ones [43]. In the latter, there is a decline in the lung compliance associated with the presence of partial or diffuse lung fibrosis. These fibrotic changes render the lung smaller and stiffer, leading to a decrease in the FVC. The FEV1/FVC ratio is reduced in obstructive patterns, but it is normal or even increased in restrictive patterns as both nominator and denominator proportionally change.
Data collection form
Different sections were included. The first was the demographic section, which contained questions regarding age, gender, education level, health history, smoking status and body mass index. Then, spirometry was performed using a Spirometer apparatus. Regular guidelines for spirometer testing were followed [44]. The subjects were seated during the test, with the nose clipped to prevent air leakage through the nares. Three attempts for each subject were allowed, and the best Spirograph was selected automatically by the spirometer. Forced spirometry was measured for each subject. For each subject, FEV1, FVC, FEV1/FVC ratios were assessed.
Data analysis
All data has been entered and analyzed using the statistical software package SPSS (Statistical Package for the Social Sciences) version 16. The main study outcomes were tested for normality using Shapiro-Wilk significant test and found not to be normally distributed. Qualitative variables have been expressed as frequency tables and bar charts. The non-parametric Two-related samples Wilcoxon test was used to test for the differences in the means between pre- and post-inhalers of the continuous outcomes. P-value of less than 0.05 was always considered statistically significant.
Results
Socio-demographic characteristics
All participants were single. The mean age (standard deviation; SD) of M. spicata group participants was 19.10 (1.45) years and 50 % of them were smoking 1–10 cigarettes per day. In the C. sinensis group, however, the mean age (SD) was 19.80 (1.22) years and the vast majority (90 %) were non-smokers. Table 1 shows the socio-demographic characteristics details of the study participants for each group.
Table 1
Socio-demographic characteristics of the study population given M. spicata and C. sinensis oils (N = 10 for each group)
Variable
M. spicata oil group
C. sinensis oil group
n (%)a
Gender
-Male
10 (100)
10 (100)
Marital status
-Single
10 (100)
10 (100)
Smoking status (cigarette/day)
-Non-smokers
4 (40)
9 (90)
-1-10
5 (50)
1 (10)
-11-20
1 (10)
0 (0)
Age (year)
19.10 ± 1.45b
19.80 ± 1.22b
Weight (kg)
70.30 ± 5.33b
73.10 ± 8.77b
Height (meter; m)
1.77 ± 0.038b
1.78 ± 0.056b
BMI (kg/m2)
22.49 ± 2.19b
22.90 ± 2.93b
aData is presented as frequency (percent) (N = 10). bMean ± standard deviation
Respiratory parameters assessment
A lung function test showed an improvement on the lung status for the students after their inhalation of the oils. Figure 1 showed that the normal spirometry results were 50 %, while after inhalation with M. spicata oil the ratio were 60 %. On the other hand, there were a more increase in normal lung status for students who inhaled C. sinensis oil (40 % before and 70 % after; Fig. 2).
Fig. 1
Respiratory parameters for participants before and after inhalation of M. spicata oil
Fig. 2
Respiratory parameters for participants before and after oil inhalation of C. sinensis oil
Interestingly, Table 2 shows that there is a significant increase in FEV1 and FVC in the post-test students after their inhalation of the M. spicata and C. sinensis oils.
Table 2
Respiratory parameters in the post- and pre-inhalers measurements for the study outcomes of the participants given M. spicata (n = 10) and C. sinensis oils (n = 10) when running equal distance of 1500 m before and after
Outcome variable
M. spicata oil group
C. sinensis oil group
Mean ± SDa
Mean difference ± SD
P-value*
Mean ± SDa
Mean difference ± SD
P-value*
FEV1
- Post-inhaler
4.47 ± 0.23
4.66 ± 0.33
- Pre-inhalers
3.72 ± 1.00
0.75 ± 1.16
0.074***
3.83 ± 1.39
0.83 ± 1.50
0.037**
FVC
- Post-inhaler
5.32 ± 0.31
5.57 ± 0.44
- Pre-inhalers
4.41 ± 0.58
0.91 ± 0.75
0.007**
3.99 ± 1.45
1.57 ± 1.59
0.005**
FEV1/FVC
- Post-inhaler
84.10 ± 0.31
84.10 ± 0.31
- Pre-inhalers
85.00 ± 20.43
−0.90 ± 20.35
0.574
94.10 ± 8.58
−1.00 ± 8.56
0.021**
*P-value for the mean differences of the Two-related samples Wilcoxon test. ** Significance P-values (less than 0.05), *** A borderline significance
aSD, standard deviation; FEV1, Forced Expiratory Volume in the first second; FVC, Forced Vital Capacity. FEV1/FVC, Ratio of FEV1 over FVC
The FEV1/FVC ratios were not significant in M. spicata oil participant while there is a significant decrease toward the normal in C. sinensis oil participants.
Furthermore, there was a statistically significant reduction in the mean running time after inhalation of M. spicata oil and C. sinensis oil among the study participants (p-values, 0.007 and 0.005; respectively) as shown in Table 3.
Table 3
Changes in exercise performance (time in seconds) for the participants given M. spicata (n = 10) and C. sinensis oils (n = 10) when running equal distance of 1500 m before and after oil inhalations
Outcome variable
M. spicata oil group
C. sinensis oil group
Mean ± SDa
Mean difference ± SD
P-value*
Mean ± SDa
Mean difference ± SD
P-value*
Time (sec)b
300.50 ± 19.89
294.70 ± 14.20
- Post-inhaler
340.70 ± 16.08
347.90 ± 15.59
-
- Pre-inhalers
−40.2 ± 2.32
0.007**
53.20 ± 7.94
0.005**
*P-value for the mean differences of the Two-related samples Wilcoxon test. ** Significant P-values (less than 0.05)
aSD, standard deviation
bData in the table is expressed as seconds
Discussion
Our findings showed that the essential oils isolated from M. spicata leaves and C. sinensis flowers enhanced athletic performance and lung function. Results showed that there is a significant increase in FEV1 and FVC in the post-test students after their inhalation of the M. spicata and C. sinensis oils. Furthermore, the running times for each group were significantly decreased for both M. spicata and C. sinensis nebulized groups (p-values, 0.007 and 0.005; respectively).
A scientific Study which was conducted by Saeki and Tanaka, 2005 had approved that an inhaling fragrances had affected the relieving of pricking pain sensation and suppressed autonomic responses and they suggested that aromatherapy may have more palliative effect on chronic rather than pricking pain [45].
Studies have shown that inhalations of various species of peppermint were effective in reducing muscle pain and fatigue as well as they had muscle relaxation effect [46–48].
Another investigation was conducted by McKenzie and Hedge, 2005 [49] about the effects of inhalation of peppermint oil on running performance under different conditions. Eighteen young female subjects run 3.25 miles and were divided into groups; wearied a peppermint scented mask group, and unscented mask group. The results showed that peppermint inhalation had significantly lower heart rates during the running task.
A study of Dedeçay’s, 1995 [50] showed that the aqueous solution containing rosemary and peppermint which was given to French cyclists made muscle relaxation and decreased muscular fatigues. Further to this, studies on peppermint inhalation had approved that this plant essential oil reduced the perceived efforts, temporal workload, physical workload and frustration [51–53].
Another study was conducted by Asghar S., 2011, on the effects of peppermint inhalation on VO2 max and reaction time, on 20 male athletes voluntarily participated in the study and the results showed that there is a meaningful relationship between the inhalation of peppermint with aerobic performance and reaction time [54].
Results of the current study, confirmed with the findings of Meamarbashi and Rajabi, 2013 and Raudenbush et al., 2001, who examined the effects of the administration of peppermint on the performance of athletes during exercises [51, 55].
Natural plants essential oils have been traditionally used in the treatment of various physiological and psychological disorders. The use of essential oils in medicine began in the ancient Egyptian Era, and has continued ever since [56, 57]. One of the most popular parts of complementary and alternative medicine is considered to be aromatherapy, which depends only on essential oils utilization for treatment of various diseases and this branch has spread worldwide, despite the lack of scientific basis for the effectiveness of essential oils [58]. On the other hand, the long history of essential oils usages in medicine and pharmacy suggests that they may indeed be effective. The odor of essential oils is believed to be important for their effectiveness in treating various illnesses [59].
Most of the essential oils are considered to be safe and their safety had been monitored in different ways, as well as these essential oils had been used from the ancient times in perfumery, cosmetics and food industries [60]. Most of these studies focused on peppermint plant but unfortunately and according to the best of authors’ knowledge there were no previous studies about M. spicata and C. sinensis oils inhalations on the lung function and on the athletic performance.
Future study is needed to demonstrate oral supplementation of M. spicata and C. sinensis essential oils to improve athletic performance and post-exercise recovery; another future objective would be to clarify their mechanism of action and to explain their physiological and pharmacological effects.
Study limitations
This study could have some limitations. The absent of control groups is one of the limitations. However, no control groups have been proposed in order to ensure that the intervention reaches the maximum number of students agreed to participate. In addition, in the design could also be another source of limitations in this study. Indeed, we conduct a non-randomized quasi-experimental uncontrolled before-and-after study. However, we are aware that in this design secular trends or sudden changes make it difficult to attribute observed changes to the intervention. Further limitations of this design could be that the occurrence of over-estimation of the effects of intervention. Interestingly enough, by using this design we were able to measure performance before and after the introduction of intervention in the same study group and the observed differences in performance were assumed to be due to the intervention. This study design has the advantages of that it is relatively simple to conduct and participants are having same characteristics pre-and post test and it is a design superior to observational studies. Furthermore, due to lack of resources and difficulty of circumstances in our country and university we found this the most robust design possible to minimize bias and maximize generalisability.
Regarding the small sample size which could have affected the study statistical power, we are fully aware of this limitation but we were not be able to recruit more due to voluntary participation. Therefore, we found it fairly enough to divide the 20 students ten by ten in each group in order to run this study. We also did not conduct between group changes as we did not aim to perform comparison between the two groups with the different oils intervention but we only aimed to assess the outcome for each intervention in the same group pre-and post test.
As we have indicated above, we used a quasi-experimental uncontrolled before-and-after study design and we did not aim to compare between groups, therefore, differences in smoking or any other variations between groups were not taken into consideration in the analysis as we have measured the changes for each intervention separately among the same group pre- and post test.
There was no dietary control in this study. However, we believe that those are informative groups of students who might have same weekly dietary intake level and we asked them to restrict any energy stimulator intakes during the week of the study. Therefore, dietary intake could have minimal effects on our findings.
Conclusions
To our knowledge, this is the first study that explored the effect of inhalation of M. spicata and C. sinensis essential oils on exercise performance and lung function. Our findings support the effectiveness of M. spicata and C. sinensis essential oils on the exercise performance and respiratory function parameters. However, our conclusion and generalisability of our results should be interpreted with caution due to small sample size and lack of control groups, randomization or masking. No control groups have been proposed in order to ensure that the intervention reaches the maximum number of students agreed to participate. We recommend further investigations to explain the mechanism of actions for these two essential oils on exercise performance and respiratory gas exchange parameters. Differences in running distance, duration of study and inhalation of two different unstudied before essential oils instead of inhalation of peppermint aroma could be the important characteristics of this study compared to previous researches.
Abbreviations
C. sinensis
:
Citrus sinensis
FEV1:
Forced Expiratory Volume in the first second
FVC:
Forced vital capacity
M. spicata
:
Mentha spicata
Declarations
Acknowledgements
The authors acknowledge the assistance of the technicians Mohamad Arar and Linda Isa as well as An-Najah National University for its support.
Funding
None.
Availability of data and materials
Data are all contained within the article.
Authors’ contributions
NJ wrote the manuscript, NJ, HA, BR, AH, JS carried out experiments. BM, AK and AI supervised research work and drafted the manuscript. All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
All authors gave their consent for the publication of the manuscript for Nidal Jaradat to be the corresponding author.
Ethics approval and consent to participate
The study aims, protocols and the informed consent forms were approved by the Institutional Review Board (IRB) at An-Najah National University (IRB archived number 1/May/ 2016). The study was conducted in accordance with the requirements of the declarations of Helsinki. All participants gave their signed informed consent before they entered in the study. Participants were not offered any incentives and they were able to withdraw from the study at anytime. Data obtained was kept confidential. Participants were assured that refusal to participate in the study would not affect their future healthcare delivery in any way. Two trained research assistants conducted the face to face interviews with the volunteers.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. 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.
Authors’ Affiliations
(1)
Department of Pharmacy, Faculty of Medicine and Health Sciences, An-Najah National University
(2)
Public Health Division, Faculty of Medicine and Health Sciences, An-Najah National University
(3)
Physiology, Pharmacology and Toxicology Division, Faculty of Medicine and Health Sciences, An-Najah National University
(4)
Faculty of Physical Education, An-Najah National University
(5)
Faculty of Law, An-Najah National University
(6)
Department of Chemistry, Arab American University of Jenin
(7)
Faculty of Humanities, An-Najah National University
References
WHO. World Health Organization Traditional Medicines Strategy 2014–2023. Geneva: WHO Press; 2013.Google Scholar
James PB, Bah AJ, Kondorvoh IM. Exploring self-use, attitude and interest to study complementary and alternative medicine (CAM) among final year undergraduate medical, pharmacy and nursing students in Sierra Leone: a comparative study. BMC Complement Altern Med. 2016;16(1):1–8.View ArticleGoogle Scholar
van der Watt G, Laugharne J, Janca A. Complementary and alternative medicine in the treatment of anxiety and depression. Current Opinion in Psychiatry. 2008;21(1):37–42.View ArticlePubMedGoogle Scholar
Cavanagh H, Wilkinson J. Biological activities of lavender essential oil. Phytother Res. 2002;16(4):301–8.View ArticlePubMedGoogle Scholar
Baser KHC, Buchbauer G. Handbook of Essential Oils: Science, Technology, and Applications. United States: CRC Press; 2015.View ArticleGoogle Scholar
Heuberger E. 10 Effects of Essential Oils in the Central Nervous System. United States: CRC Press; 2009. p. 281.Google Scholar
Esposito ER, Bystrek MV, Klein JS. An elective course in aromatherapy science. Am J Pharm Educ. 2014;78(4):1–9.View ArticleGoogle Scholar
Sayowan W, Siripornpanich V, Hongratanaworakit T, Kotchabhakdi N, Ruangrungsi N. The effects of jasmine Oil inhalation on brain wave activies and emotions. J Health Res. 2013;27(2):73–7.Google Scholar
Stewart D. The Chemistry of Essential Oils Made Simple: God’s Love Manifest in Molecules. UK: Care Publications; 2005.Google Scholar
Yan L, Wang J, Kim H, Meng Q, Ao X, Hong S, et al. Influence of essential oil supplementation and diets with different nutrient densities on growth performance, nutrient digestibility, blood characteristics, meat quality and fecal noxious gas content in grower–finisher pigs. Livest Sci. 2010;128(1):115–22.View ArticleGoogle Scholar
Schulz V, Hänsel R, Tyler VE. Rational Phytotherapy: A physician’s Guide to Herbal Medicine. UK: Psychology Press; 2001.View ArticleGoogle Scholar
Khan IA, Abourashed EA. Leung’s Encyclopedia of Common Natural Ingredients: Used in Food, Drugs and Cosmetics. United States: Wiley; 2011.Google Scholar
Dorman H, Deans S. Antimicrobial agents from plants: antibacterial activity of plant volatile oils. J Appl Microbiol. 2000;88(2):308–16.View ArticlePubMedGoogle Scholar
Raut JS, Karuppayil SM. A status review on the medicinal properties of essential oils. Ind Crop Prod. 2014;62:250–64.View ArticleGoogle Scholar
Freiesleben SH, Soelberg J, Jäger AK. Medicinal plants used as excipients in the history in Ghanaian herbal medicine. J Ethnopharmacol. 2015;174:561–8.View ArticlePubMedGoogle Scholar
Knasko SC. Ambient odor’s effect on creativity, mood, and perceived health. Chem Senses. 1992;17(1):27–35.View ArticleGoogle Scholar
Chebat J-C, Michon R. Impact of ambient odors on mall shoppers’ emotions, cognition, and spending: a test of competitive causal theories. J Bus Res. 2003;56(7):529–39.View ArticleGoogle Scholar
Ceccarelli I, Lariviere WR, Fiorenzani P, Sacerdote P, Aloisi AM. Effects of long-term exposure of lemon essential oil odor on behavioral, hormonal and neuronal parameters in male and female rats. Brain Res. 2004;1001(1):78–86.View ArticlePubMedGoogle Scholar
Sellaro R, Hommel B, Paccani CR, Colzato LS. With peppermints you’re not my prince: aroma modulates self-other integration. Atten Percept Psychophys. 2015;77(8):2817–25.View ArticlePubMedPubMed CentralGoogle Scholar
Aydin E, Hritcu L, Dogan G, Hayta S, Bagci E. The effects of inhaled Pimpinella peregrina essential Oil on scopolamine-induced memory impairment, anxiety, and depression in laboratory rats. Mol Neurobiol. 2016;1–11.Google Scholar
Edewor-Kuponiyi TI. Plant-derived compounds with potential sedative and anxiolytic activities. Int J Basic Appl Sci. 2013;2(1):63–78.Google Scholar
Ahmed HM. Ethnopharmacobotanical study on the medicinal plants used by herbalists in Sulaymaniyah Province, Kurdistan, Iraq. J Ethnobiol Ethnomed. 2016;12(1):1–17.View ArticleGoogle Scholar
Khan IA. Citrus Genetics, Breeding and Biotechnology. United Kingdom: CABI; 2007.View ArticleGoogle Scholar
Vankar PS. Essential oils and fragrances from natural sources. Resonance. 2004;9(4):30–41.View ArticleGoogle Scholar
Prabuseenivasan S, Jayakumar M, Ignacimuthu S. In vitro antibacterial activity of some plant essential oils. BMC Complement Altern Med. 2006;6(1):1–9.View ArticleGoogle Scholar
Abufarha N. Land of symbols: cactus, poppies, orange and olive trees in Palestine. Identities: Global Studies in Culture and Power. 2008;15(3):343–68.View ArticleGoogle Scholar
Hussain AI, Anwar F, Shahid M, Ashraf M, Przybylski R. Chemical composition, and antioxidant and antimicrobial activities of essential oil of spearmint (Mentha spicata L.) from Pakistan. J Essent Oil Res. 2010;22(1):78–84.View ArticleGoogle Scholar
Lawrence B. The Composition of Commercially Important Mints. New York: Taylor & Francis Group; 2007. p. 88–9.Google Scholar
Asekun O, Grierson D, Afolayan A. Effects of drying methods on the quality and quantity of the essential oil of Mentha longifolia L. subsp. Capensis. Food Chem. 2007;101(3):995–8.View ArticleGoogle Scholar
Scherer R, Lemos MF, Lemos MF, Martinelli GC, Martins JDL, da Silva AG. Antioxidant and antibacterial activities and composition of Brazilian spearmint (Mentha spicata L.). Ind Crop Prod. 2013;50:408–13.View ArticleGoogle Scholar
Kizil S, Hasimi N, Tolan V, Kilinc E, Yuksel U. Mineral content, essential oil components and biological activity of two mentha species (M. piperita L., M. spicata L.). Turkish J Field Crops. 2010;15(2):148–53.Google Scholar
Kunnumakkara AB, Koca C, Dey S, Gehlot P, Yodkeeree S, Danda D, et al. Traditional uses of spices: an overview. Molecular targets and therapeutic uses of spices World Scientific, New Jersey. 2009;1–24.Google Scholar
Brusasco V, Pellegrino R. Spirometry in chronic obstructive pulmonary disease. From rule of thumb to science. Am J Respir Crit Care Med. 2016;193(7):704–6.View ArticlePubMedGoogle Scholar
Walker BR, Colledge NR. Davidson’s Principles and Practice of Medicine. UK: Elsevier Health Sciences; 2013.Google Scholar
Holguin F. The metabolic syndrome as a risk factor for lung function decline. Am J Respir Crit Care Med. 2012;185(4):352–3.View ArticlePubMedGoogle Scholar
Abuzant O, Rahhal B, Hanbali M. The Influence of Working in Charcoal Factories on Selected Respiratory Parameters. An - Najah University Journal Research. 2015;29:59–72.Google Scholar
Loscalzo J. Harrison’s Pulmonary and Critical Care Medicine. New York: McGraw-Hill Medical; 2013.Google Scholar
Jaradat NA. Quantitative estimations for the volatile Oil by using hydrodistillation and microwave accelerated distillation methods from Ruta graveolens L. and Ruta chalepensis L. leaves from Jerusalem area/Palestine. Moroccan J Chem. 2016;4:1–6.Google Scholar
Spencer MR, Gastin PB. Energy system contribution during 200-to 1500-m running in highly trained athletes. Med Sci Sports Exerc. 2001;33(1):157–62.View ArticlePubMedGoogle Scholar
Schneider A, Gindner L, Tilemann L, Schermer T, Dinant G, Meyer FJ, et al. Diagnostic accuracy of spirometry in primary care. BMC Pulmonary Medicine. 2009;9(1):31–9.View ArticlePubMedPubMed CentralGoogle Scholar
Quadrelli S, Bosio M, Salvado A, Chertcoff J. Valor de la espirometria para el diagnostico de restricción pulmonar. Medicina. 2007;67(6):685–90.PubMedGoogle Scholar
Pellegrino R, Viegi G, Brusasco V, Crapo R, Burgos F, Casaburi R, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948–68.View ArticlePubMedGoogle Scholar
Derom E, Van Weel C, Liistro G, Buffels J, Schermer T, Lammers E, et al. Primary care spirometry. Eur Respir J. 2008;31(1):197–203.View ArticlePubMedGoogle Scholar
Broekhuizen BD, Sachs AP, Hoes AW, Moons KG, van den Berg JW, Dalinghaus WH, et al. Undetected chronic obstructive pulmonary disease and asthma in people over 50 years with persistent cough. Br J Gen Pract. 2010;60(576):489–94.View ArticlePubMedPubMed CentralGoogle Scholar
Saeki Y, Tanaka Y. Effect of inhaling fragrances on relieving pricking pain. Int J Aromather. 2005;15(2):74–80.View ArticleGoogle Scholar
Mimica-Dukic N, Jakovljevic V, Sabo A, Popovic M, Lukic V, Gasic O, et al. Evaluation of some pharmacodynamic effects of Mentha longifolia extracts. Planta Med. 1993;59:691–9.View ArticleGoogle Scholar
Forster H, Niklas H, Lutz S. Antispasmodic effects of some medicinal plants. Planta Med. 1980;40:309–419.View ArticlePubMedGoogle Scholar
Bremness L. The Complete Book of Herbs. London: Ward Lock Limited; 1988.Google Scholar
MacKenzie CM, Hedge A. Is peppermint an ergogenic Aid to athletic performance? Rev Hum Factors Ergon. 2005;49:1229–33.Google Scholar
Dedecay S. The odor and therapeutic effects of the plants found in Cyprus. J Nicosia Private Turkish Univ. 1995;1:137–44.Google Scholar
Raudenbush B, Corley N, Eppich W. Enhancing athletic performance through the administration of peppermint odor. J Sport Exercise Psychol. 2001;23(2):156–60.View ArticleGoogle Scholar
Raudenbush B, Meyer B, Eppich B. The effects of odors on objective and subjective measures of athletic performance. Int Sports J. 2002;6(1):14–27.Google Scholar
Spotten L, Corish C, Lorton C, Dhuibhir PU, O’Donoghue N, O’Connor B, et al. Subjective taste and smell changes in treatment-naive people with solid tumours. Support Care Cancer. 2016;1–8.Google Scholar
Asghar S. Effects of Mentha piperita inhalation on VO2 max and reaction time, on man elite karate-do. Ann Biol Res. 2011;2:84–7.Google Scholar
Meamarbashi A, Rajabi A. The effects of peppermint on exercise performance. J Int Soc Sports Nut. 2013;10:15–20.View ArticleGoogle Scholar
Lima NG, De Sousa DP, Pimenta FCF, Alves MF, De Souza FS, Macedo RO, et al. Anxiolytic-like activity and GC–MS analysis of (R)-(+)-limonene fragrance, a natural compound found in foods and plants. Pharmacol Biochem Behav. 2013;103(3):450–4.View ArticlePubMedGoogle Scholar
Liu P, Kong M, Yuan S, Liu J, Wang P. History and experience: a survey of traditional Chinese medicine treatment for Alzheimer’s disease. Evid Based Complement Altern Med. 2014;2014:5–10.View ArticleGoogle Scholar
Goldbeck-Wood S, Dorozynski A, Lie LG, Yamauchi M, Zinn C, Josefson D, et al. Complementary medicine is booming worldwide. Br Med J. 1996;313(7050):131–4.View ArticleGoogle Scholar
Nan Lv X, Jun Liu Z, Jing Zhang H, Tzeng CM. Aromatherapy and the central nerve system (CNS): therapeutic mechanism and its associated genes. Curr Drug Targets. 2013;14(8):872–9.View ArticleGoogle Scholar
Huntley A. Aromatherapy Science: A Guide for Healthcare Professionals. United States: Pharmaceutical Press; 2006.Google Scholar
