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An investigation into the stress-relieving and
pharmacological actions of an ashwagandha
(Withania somnifera) extract
A randomized, double-blind, placebo-controlled study
Adrian L. Lopresti, PhD
a,b,∗
, Stephen J. Smith, MA
a,b
, Hakeemudin Malvi, MBBS, MD
c
, Rahul Kodgule, MBBS
d
Abstract
Background: Ashwagandha (Withania somnifera (L.) Dunal) is a herb traditionally used to reduce stress and enhance wellbeing.
The aim of this study was to investigate its anxiolytic effects on adults with self-reported high stress and to examine potential
mechanisms associated with its therapeutic effects.
Methods: In this 60-day, randomized, double-blind, placebo-controlled study the stress-relieving and pharmacological activity of
an ashwagandha extract was investigated in stressed, healthy adults. Sixty adults were randomly allocated to take either a placebo or
240 mg of a standardized ashwagandha extract (Shoden) once daily. Outcomes were measured using the Hamilton Anxiety Rating
Scale (HAM-A), Depression, Anxiety, and Stress Scale -21 (DASS-21), and hormonal changes in cortisol, dehydroepiandrosterone-
sulphate (DHEA-S), and testosterone.
Results: All participants completed the trial with no adverse events reported. In comparison with the placebo, ashwagandha
supplementation was associated with a statistically significant reduction in the HAM-A (P=.040) and a near-significant reduction in
the DASS-21 (P=.096). Ashwagandha intake was also associated with greater reductions in morning cortisol (P<.001), and DHEA-
S(P=.004) compared with the placebo. Testosterone levels increased in males (P=.038) but not females (P=.989) over time,
although this change was not statistically significant compared with the placebo (P=.158).
Conclusions: These findings suggest that ashwagandha’s stress-relieving effects may occur via its moderating effect on the
hypothalamus-pituitary-adrenal axis. However, further investigation utilizing larger sample sizes, diverse clinical and cultural
populations, and varying treatment dosages are needed to substantiate these findings.
Trial registration: Clinical Trials Registry—India (CTRI registration number: CTRI/2017/08/009449; date of registration 22/08/
2017)
Abbreviations: DASS-21 =Depression, Anxiety, and Stress Scale -21, DHEA-S =dehydroepiandrosterone sulfate, GABA =
gamma-aminobutyric acid, HAM-A =Hamilton Anxiety Rating Scale, HPA =hypothalamic-pituitary-adrenal.
Keywords: anxiety, ashwagandha, cortisol, stress, testosterone, withania somnifera
1. Introduction
Interest in herbal medicinal products and supplements is high as it
is estimated that at least 80% of people worldwide use them for
some part of their primary healthcare.
[1]
Although most
ingredients have a long history of traditional use, efficacy has
not been clearly established in clinical trials for a large portion of
them. Safety alsoremains uncertain, particularlyas cultivation and
extraction methods can vary widely. Robustly designed clinical
trials are therefore imperative to establish safety and efficacy.
Ashwagandha (Withania somnifera (L.) Dunal) is a small
shrub belonging to the Solanaceae family. It is prolifically grown
in dry regions of South Asia, Central Asia, and Africa, and
is regularly used in Ayurveda, an ancient Hindu system of
medicine.
[2]
Ashwagandha has been traditionally used to
promote “youthful vigour”by enhancing muscle strength,
endurance, and overall health.
[3]
Over 50 chemical constituents
have been identified in the various parts of the ashwagandha
plant with the major chemical constituents including steroidal
alkaloids and lactones, collectively known as withanolides.
[4]
Pharmacological studies have confirmed that plant preparation
of ashwagandha has anti-inflammatory, antioxidant, anticancer,
Editor: Daryle Wane.
This study was funded by Arjuna Natural Ltd.
This study was independently managed by the principal investigators, Dr HM and
RK, who declare no competing interests. Dr AL has received study funding from
Arjuna Natural Extracts Ltd in the past for previously completed unrelated studies
and has received compensation for conference presentations.
The authors have no conflicts of interest to disclose.
a
College of Science, Health, Engineering, and Education (SHEE), Murdoch
University, Perth,
b
Clinical Research Australia, Duncraig, Western Australia,
Australia,
c
Heamatology Centre Bhopal, Bhopal, Madhya Pradesh,
d
Saibaba
Healthcare, Wagholi, Pune, Maharashtra, India.
∗
Correspondence: Adrian L. Lopresti, 38 Arnisdale Road, Duncraig, Western
Australia 6023, Australia (e-mail: a.lopresti@murdoch.edu.au).
Copyright ©2019 the Author(s). Published by Wolters Kluwer Health, Inc.
This is an open access article distributed under the Creative Commons
Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
How to cite this article: Lopresti AL, Smith SJ, Malvi H, Kodgule R. An
investigation into the stress-relieving and pharmacological actions of an
ashwagandha (Withania somnifera) extract. Medicine 2019;98:37(e17186).
Received: 10 May 2019 / Received in final form: 8 August 2019 / Accepted: 21
August 2019
http://dx.doi.org/10.1097/MD.0000000000017186
Clinical Trial/Experimental Study Medicine®
OPEN
1
anxiolytic, and immunomodulatory effects. It has also been
shown to influence neurological, endocrine, and cardiovascular
activity.
[3,5]
In animal stress models, ashwagandha has been
shown to possess anxiolytic, antidepressant, and neuroprotective
effects.
[6–8]
Moreover, animal studies have also confirmed
ashwagandha’sinfluence on sex hormone production, as
demonstrated by its effects on luteinizing hormone, follicle-
stimulating hormone, testosterone, and progesterone.
[9–11]
Stress is a general term defined as the nonspecific response of
the body to any demand for change.
[12]
It is a major exacerbating
factor for both hypertension and diabetes which are major killers
worldwide.
[13–15]
High stress is also a common trigger for mood
disorders such as anxiety and depression.
[16,17]
As an agent to
modulate stress and anxiety, ashwagandha has been investigated
in several human trials. In 2, double-blind, placebo-controlled
studies, ashwagandha was associated with greater reductions in
anxiety in adults presenting with predominately generalized
anxiety disorder.
[18,19]
In an 8-week, randomized, double-blind,
placebo-controlled study ashwagandha was associated with
greater reductions in anxiety, morning cortisol, c-reactive
protein, pulse rate, and blood pressure in chronically stressed
adults.
[20]
Greater increases in serum dehydroepiandrosterone
sulfate (DHEA-S) and hemoglobin were also noted. Further
randomized, double-blind, placebo-controlled studies have
confirmed ashwagandha’s anti-stress and cortisol-lowering
effects in adults with self-reported chronic stress
[21]
and
chronically stressed overweight and obese adults.
[22]
In all these
studies ashwagandha was well tolerated with minimal adverse
effects reported.
These positive trials investigating the anxiolytic and mood-
enhancing effects of ashwagandha in adults provide increasing
support for the efficacy of this herbal agent for adults suffering
from stress and anxiety. Outcomes used to measure efficacy
included self-report and clinician-rated instruments, along with
measures of physiological markers that are commonly associated
with stress and anxiety, including cortisol, pulse rate, and blood
pressure. However, the strength of findings is hampered by the
small sample sizes used and short treatment duration with no study
greater than 8 weeks. In these studies, divergent ashwagandha
extracts with varying treatment doses were also used.
The aim of this study was to add to the current body of
evidence by investigating the antistress effects and safety profile of
a standardized ashwagandha root extract (Shoden) in healthy
adults suffering from mild stress. In this 60-day, randomized,
double-blind, placebo-controlled study we were also interested in
identifying additional mechanisms of ashwagandha’s antistress,
and mood-enhancing effects, particularly in relation to its
influence on steroidal hormones. Accordingly, we examined
changes in morning cortisol, DHEA-S, and testosterone levels.
We hypothesized that ashwagandha would result in greater
reductions in stress and anxiety, serum cortisol, and DHEA-S.
As there have been some studies confirming the positive effects
of ashwagandha on testosterone, we also predicted greater
elevations in serum testosterone levels over time, compared with
the placebo.
[23,24]
2. Methods
2.1. Study design
This study was a 60-day, randomized, double-blind, placebo-
controlled trial evaluating the efficacy and tolerability of an
ashwagandha extract on stress, anxiety, and hormone produc-
tion in healthy adults. The study protocol was approved by
Nagpur Independent Ethics Committee and retrospectively
registered with the Clinical Trials Registry- India (CTRI
registration number: CTRI/2017/08/009449; date of registration
22/08/2017) with participant recruitment occurring between
April 2016 and July 2016. The methods were carried out in
accordance with the relevant guidelines and regulations. Details
of the study design are outlined in Fig. 1.
An a priori power analysis was undertaken to estimate the
required sample size. We predicted a Cohen’s d effect size of 0.8
for the treatment group. Assuming a power of 80%, a type 1 error
rate (alpha) of 5%, and a 10% drop-out rate, the total number of
participants to find an effect was estimated as 57. Enrolled
participants were assigned to either 1 of the 2 study groups
(ashwagandha or placebo) using a random number table. A
randomization list with only the randomization numbers was
provided to the study site for the purpose of enrolling volunteers
in the study. The master randomization list with the details of
allocation was kept safely and confidentially with the study
sponsor.
Potential participants were screened after completing a signed
informed consent and 60 eligible participants were enrolled in the
study as per inclusion and exclusion criteria. Participants
attended on 6 occasions to 1 of 2 healthcare centers located in
India (Haematology Centre in Bhopal or Sai Baba Healthcare in
Pune). During visit 1 (initial assessment conducted approximately
7 days prior to commencement of capsule intake) the following
information was collected, or examinations conducted: informed
consent, demographic data, medical history, physical, and
systemic examination (vital parameters, respiratory rate, electro-
cardiography, chest x-ray, hematology, biochemistry, and
serology), and in women of child-bearing age a pregnancy test
was undertaken. Baseline outcome measures were also collected
including a morning blood sample (to assess DHEA-S, cortisol,
and testosterone), clinician-administered Hamilton Anxiety
Rating Scale (HAM-A), and self-report Depression, Anxiety,
Stress Scale-21 (DASS-21).
On visit 2 (baseline/day 0) eligible participants meeting criteria
eligibility were randomized into 1 of 2 treatment conditions
(ashwagandha or placebo). Participants were provided with a
15-day supply of capsules. At visits 3 (day 15), 4 (day 30), 5
(day 45), and 6 (day 60), participants returned to the center, and
the following was undertaken: vitals and a physical examination,
count of returned pills, provision of new pills, rating admin-
istrations (HAM-A and DASS-21), and record of any adverse
events. At visit 4 (day 30) and visit 6 (day 60) a morning blood
sample was also collected to assess for cortisol and DHEA-S.
Assessment of testosterone levels was only undertaken at baseline
and day 60.
2.2. Participants
Volunteers were obtained from the general population who
visited 1 of 2 healthcare centers in India (Haematology Centre in
Bhopal or Sai Baba Healthcare in Pune) for a routine health
check. Participants were informed about the study, and if
agreeable, were assessed by the principal investigator for
eligibility based on the following inclusion/exclusion criteria:
2.2.1. Inclusion criteria. Healthy male and female adults aged
between 18 and 65 years with a HAM-A between 6 and 17 were
Lopresti et al. Medicine (2019) 98:37 Medicine
2
eligible to participate. Participants were also willing to participate
in the study and comply with its procedures by signing a written
informed consent. Female participants of child-bearing age were
required to be using a suitable and effective contraceptive method
throughout the study and tested negatively on a pregnancy
screen. Non-child-bearing women were postmenopausal for
at least 12 consecutive months or had undergone surgical
sterilization. All participants were encouraged to not make any
major lifestyle changes during the study period. They were
informed that any major changes may result in exclusion from the
study.
2.2.2. Exclusion criteria. Participants were ineligible for
participation in the study if they were pregnant, lactating, or
were not using an appropriate method of birth control. People
with a known hypersensitivity to ashwagandha were also
excluded. Individuals with acute narrow-angle glaucoma,
prostate hypertrophy, cardiovascular, endocrine or renal disease,
or another chronic disease that could affect stress/anxiety or
restrict normal, daily function were also ineligible to participate
in the study. Individuals who currently, or in the past 6 months,
suffered from any diagnosable mental-health disorder (as
assessed by the Mini International Neuropsychiatric Interview
6.0) or were taking a psychotropic medication or other herbal
preparation were also excluded from participating in the study.
People with reported alcohol dependence or were taking any
other investigational drug for another clinical trial/research were
also ineligible.
Figure 1. Systematic illustration of study design.
Lopresti et al. Medicine (2019) 98:37 www.md-journal.com
3
2.3. Interventions
Capsules containing either 240 mg of an ashwagandha extract
(Shoden) or placebo (roasted rice powder) manufactured by
Arjuna Natural Ltd, Aluva, Kerala, India were used for the
intervention and placebo groups respectively. The dried plant
material was visually identified by a qualified botanist as
Withania somnifera (L.) Dunal and was purchased from a
commercial supplier (Neemuch, Madhya Pradesh, India). The
extraction solvent used was ethanol:water at a proportion of
70:30 and the extract was standardized by high-performance
liquid chromatography to contain 35% withanolide glycosides.
Participants were instructed to take 1 capsule (with 84 mg
withanolide glycosides), once daily after dinner with 250 mL of
water. Capsules were identical in appearance, shape, color, and
packaging, comprising oblong green-colored capsules.
2.4. Outcome measures
2.4.1. Primary outcome measure 1: Hamilton Anxiety Rating
Scale (HAM-A). The HAM-A is a widely used, well-validated
tool consisting of 14 items designed to assess the severity of a
patient’s anxiety.
[25]
In this clinician-rated measure, each of the
14 items is rated on a 5-point scale, ranging from 0=not present
to 4=severe. The HAM-A was completed at initial assessment (7
days prior to capsule administration) and 15, 30, 45, and 60 days
after commencement of capsule intake.
2.4.2. Primary outcome 2: Depression, Anxiety, Stress
Scale-21 (DASS-21). The DASS-21 is a validated self-report
measure assessing symptoms of stress, anxiety, and depres-
sion.
[26]
Twenty-one questions are rated on a 4-point scale (0–3),
ranging from never to almost always (lower scores indicate a
reduction in symptoms). The DASS-21 was completed at initial
assessment (7 days prior to capsule administration) and 15, 30,
45, and 60 days after commencement of capsule intake.
2.4.3. Secondary outcome measures 1 to 3: serum cortisol,
DHEA-S, testosterone. A morning, fasting (approximately 8
AM), venepuncture blood sample was collected from participants
at the 2 site locations. Levels of serum cortisol and testosterone
were measured with the ADVIAÒ Centaur System using
competitive immunoassay direct chemiluminescent technology.
The IMMULITE 2000 Systems Analyzer was used for the
quantitative measurement of DHEA-SO4 in serum. Cortisol and
DHEA-S levels were measured at initial assessment (7 days prior
to capsule administration), 30 and 60 days after commencement
of capsule intake. Testosterone was measured at initial assess-
ment and 60 days after commencement of capsule intake.
2.4.4. Safety assessments. Hematological assessments were
undertaken at initial assessment (7 days prior to capsule
administration) and 60 days after commencement of capsule
intake. These comprised the following: complete blood count
(red blood cell, white blood cell, hemoglobin, hematocrit,
platelets, and erythrocyte sedimentation rate) and a lipid profile
(low-density lipoprotein, cholesterol, high-density lipoprotein,
triglycerides, and very-low-density lipoprotein).
2.5. Statistical analysis
An independent samples ttest was used to compare demographic
variables across the 2 treatment groups for continuous variables,
and Pearson x
2
was used to compare categorical data. Total
scores on the HAM-A, DASS-21 (days 0, 15, 30, 45, and 60), and
cortisol, DHEA-S (days 0, 30, and 60) were analyzed for time and
treatment (ashwagandha and placebo) effects using a mixed
repeated-measures analysis of variance (ANOVA). A paired-
samples ttest was used to analyze changes in testosterone (days 0
and 60) over time. Eta-squared (h
2
) was calculated to examine
effect sizes.
There were no significant outliers in data as assessed by the
visual inspection of Q-Q plots. The Shapiro–Wilk normality test
was conducted to examine the normality of group data. This
demonstrated that hormonal data were not normally distributed,
and transformations were unable to normalize data. However, a
repeated-measures ANOVA was considered the most appropri-
ate option for statistical analyses as it is relatively robust to
violations of normality.
[27]
For all the tests, statistical significance
was set at P<.05 (2-tailed). All data were analyzed using SPSS
(version 24; IBM, Armonk, NY).
3. Results
3.1. Demographic details and baseline data
A total of 60 participants (37 males and 23 females) were enrolled
in the study with all volunteers completing the 60-day trial. Data
was also collected in full, with no missing data from assessment
instruments. Demographic characteristics are shown in Table 1
and indicate that the study population was homogeneous, with
no statistically significant differences between the groups on
demographic characteristics.
3.1.1. Primary outcome measure 1: HAM-A. Changes in
HAM-A scores across the 2 treatment groups and repeated
measures ANOVA significance levels are detailed in Table 2 and
Fig. 2. A statistically significant 41% reduction in HAM-A
was observed over time in the ashwagandha group (F
4,116
=
15.09, P<.001) and a 24% reduction in the placebo group
Table 1
Participant baseline demographic characteristics.
Placebo
(mean and SE)
Ashwagandha
(mean and SE) Pvalue
Female (n) 12 11 .791
†
Male (n) 18 19
Age 40.23 (2.43) 42.23 (2.44) .610
‡
Weight (kg) 65.43 (1.99) 63.83 (1.78) .551
∗
BMI 26.04 (0.65) 24.68 (0.60) .196
‡
Outcome measures
HAM-A 9.73 (0.50) 10.27 (0.59) .491
∗
DASS-21 16.40 (1.06) 16.83 (0.94) .760
∗
Cortisol (mcg/dL) 14.00 (1.04) 14.15 (0.84) .824
‡
Males (n =37) 15.62 (1.31) 14.26 (1.12) .434
∗
Females (n =23) 11.57 (1.50) 13.95 (1.27) .242
∗
DHEA-S (mcg/dL) 236.28 (25.55) 218.93 (31.96) .359
‡
Males (n =37) 237.89 (37.45) 217.80 (37.49) .707
∗
Females (n =23) 233.87 (32.40) 220.89 (60.90) .849
∗
Testosterone (ng/dL) 341.75 (55.17) 320.72 (45.60) .819
‡
Males (n =37) 543.47 (51.43) 472.88 (39.76) .282
∗
Females (n =23) 39.18 (7.80) 57.90 (24.95) .829
‡
SE =standard error, DASS-21 =Depression, Anxiety, and Stress Scale-21, DHEA-S =
dehydroepiandrosterone sulfate, HAM-A =Hamilton Anxiety Rating Scale.
∗
Independent samples ttest.
†
Pearson x
2
test.
‡
Mann–Whitney Utest.
Lopresti et al. Medicine (2019) 98:37 Medicine
4
(F
4,116
=6.37, P<.001). A 34.2% variability across time was
observed in the ashwagandha group and an 18% variability in
the placebo group. A comparison of between-group differences
revealed a statistically significant-time x group interaction
(F
4,232
=2.55, P=.040).
3.1.2. Primary outcome measure 2: DASS-21. Changes in
DASS-21 scores across the 2 treatment groups and repeated
measures ANOVA significance levels are detailed in Table 2 and
Fig. 2. A statistically significant 30% reduction in HAM-A was
observed over time in the ashwagandha group (F
4,116
=7.03,
P<.001) and a 10% reduction in the placebo group (F
4,116
=
3.37, P=.012). A 19.5% variability across time was observed in
the ashwagandha group and a 10.4% variability in the placebo
group. A comparison of between-group differences revealed a
near-significant time x group interaction (F
4,232
=2.00, P=.096).
3.1.3. Secondary outcome measure 1: cortisol. Changes in
cortisol scores across the 2 treatment groups and repeated
measures ANOVA significance levels are detailed in Table 3 and
Fig. 3. In the ashwagandha group, a statistically significant 23%
reduction in cortisol was observed over time (F
2,58
=10.25,
P=<.001). However, no significant change occurred in the
placebo group (0.5% increase) (F
2,58
=0.22, P=.800). A 26.1%
variability across time was observed in the ashwagandha group
and a 0.8% variability in the placebo group. A comparison of
between-group differences revealed a statistically significant time
x group interaction (F
2,116
=8.95, P=<.001).
Gender-wise comparisons revealed there was a statistically
significant 25% reduction in cortisol in females in the
ashwagandha group (F
2,20
=4.53, P=.024) and a nonsignificant
0.6% decrease in the placebo group (F
2,22
=0.02, P=.979). A
31.2% variability across time was observed in the ashwagandha
group and a 0.2% variability in the placebo group. A comparison
of between-group differences revealed a statistically significant
time x group interaction (F
2,42
=4.31, P=.020). In males, there
was a statistically significant 22% reduction in cortisol in the
ashwagandha group (F
2,36
=5.64, P=.007) and a nonsignificant
1% increase in the placebo group (F
2,34
=0.28, P=.758). A
23.9% variability across time was observed in the ashwagandha
group and a 1.6% variability in the placebo group. A comparison
of between-group differences revealed a statistically significant
time x group interaction (F
2,70
=4.84, P=.011).
3.1.4. Secondary outcome measure 2: DHEA-S. Changes in
DHEA-S scores across the 2 treatment groups and repeated
measures ANOVA significance levels are detailed in Table 3 and
Fig. 3. In the ashwagandha group, a statistically significant 8%
reduction in DHEA-S was observed over time (F
2,58
=5.45,
P=.007). However, no significant change occurred in the placebo
group (2.5% increase) (F
2,58
=1.38, P=.260). A 15.8%
variability across time was observed in the ashwagandha group
and a 4.5% variability in the placebo group. A comparison of
between-group differences revealed a statistically significant time
x group interaction (F
2,116
=5.86, P=.004).
Gender-wise comparisons revealed a near significant 9%
reduction in DHEA-S in females in the ashwagandha group
(F
2,20
=2.90, P=.078) and a nonsignificant 1% increase in the
placebo group (F
2,22
=0.04, P=.687). A 22.5% variability across
time was observed in the ashwagandha group and a 3.4%
Table 2
Mood changes during 60-d intervention.
Questionnaire Group
Mean (SE) Repeated measures ANOVA
Day 0 Day 15 Day 30 Day 45 Day 60
Pvalue
(within group) h
2
(%)
Pvalue
(between group)
HAM-A Placebo 9.73 (0.54) 8.80 (0.54) 9.07 (0.54) 9.17 (0.52) 7.37 (0.41) <.001 18.0 .040
Ashwagandha 10.27 (0.59) 8.70 (0.62) 8.13 (0.52) 7.73 (0.51) 6.07 (0.38) <.001 34.2
DASS Placebo 16.40 (1.06) 15.80 (1.07) 15.20 (1.03) 17.70 (0.76) 14.73 (0.86) .012 10.4 .096
Ashwagandha 16.83 (1.00) 14.77 (1.07) 13.93 (1.03) 15.23 (0.76) 11.77 (0.86) <.001 19.50
DASS =Depression, Anxiety, and Stress Scale, HAM-A =Hamilton Anxiety Rating Scale.
HAM-A
12
11
10
9
8
7
6
5Day 0 Day 15 Day 30 Day 45 Day 60
Time
Placebo
Ashwagandha
DASS - TOTAL SCORE
20
19
18
17
16
15
14
13
12
11
10
Day 0 Day 15 Day 30 Day 45 Day 60
Time
Figure 2. Mean change in mood scores over time (vertical bars depict standard error bars).
Lopresti et al. Medicine (2019) 98:37 www.md-journal.com
5
variability in the placebo group. A comparison of between-group
differences revealed a near statistically significant time x group
interaction (F
2,42
=3.00, P=.061). In males, there was a near-
significant 8% reduction in DHEA-S in the ashwagandha group
(F
2,36
=2.85, P=.071) and a nonsignificant 3% increase in the
placebo group (F
2,34
=1.02, P=.369). A 13.7% variability across
time was observed in the ashwagandha group and a 5.7%
variability in the placebo group. A comparison of between-group
differences revealed a statistically significant time x group
interaction (F
2,70
=3.21, P=.046).
3.1.5. Secondary outcome measure 3: testosterone. Changes
in testosterone scores across the 2 treatment groups and repeated
measures ANOVA/ paired-samples ttest significance levels are
detailed in Table 3 and Fig. 3. In the ashwagandha group, a
statistically significant 11% increase in testosterone was observed
over time [T(29)=2.11, P=.043]. However, no significant
change occurred in the placebo group (0.1% increase) [T(29) =
0.01, P=.990]. A 13.3% variability across time was observed
in the ashwagandha group and a 0% variability in the placebo
group. A comparison of between-group differences revealed a
nonsignificant time x group interaction (F
1,58
=2.13, P=.150).
Gender-wise comparisons revealed a nonsignificant 0.2%
reduction in testosterone in females in the ashwagandha group [T
(10)=0.01, P=.989] and a nonsignificant 1.3% reduction in
the placebo group [T(11)=0.18, P=.864]. A comparison of
between-group differences revealed a nonsignificant time x group
interaction (F
1,21
=0.002, P=.965). In males, there was a
statistically-significant 11.4% increase in testosterone in the
ashwagandha group [T(18)=2.24, P=.038] and a nonsignifi-
cant 0.1% increase in the placebo group [T(17) =0.02,
P=.980]. A 21.8% variability across time was observed in the
Table 3
Hormonal changes during 60-d intervention.
Hormone Group Gender (n)
Mean (SE) Repeated measures ANOVA
Day 0 Day 30 Day 60
Pvalue
(within group) h
2
(%)
Pvalue
(between group)
Cortisol (mcg/dL) Placebo All (30) 14.00 (0.94) 13.86 (0.93) 14.07 (1.04) .800 0.8 <.001
Ashwagandha All (30) 14.15 (0.94) 12.21 (0.93) 10.84 (1.04) <.001 26.1
Placebo Female (12) 11.57 (1.37) 11.51 (1.31) 11.50 (1.56) .979 0.2 .020
Ashwagandha Female (11) 13.95 (1.43) 11.47 (1.37) 10.43 (1.62) .024 31.2
Placebo Male (18) 15.62 (1.23) 15.42 (1.24) 15.78 (1.35) .758 1.6 .011
Ashwagandha Male (19) 14.26 (1.20) 12.63 (1.20) 11.07 (1.32) .007 23.9
DHEA-S (mcg/dL) Placebo All (30) 236.28 (28.93) 237.06 (28.08) 242.28 (27.41) .260 4.5 .004
Ashwagandha All (30) 218.93 (28.93) 202.19 (28.08) 201.08 (27.41) .007 15.8
Placebo Female (12) 233.87 (46.57) 233.24 (43.88) 236.59 (41.44) .687 3.4 .061
Ashwagandha Female (11) 220.90 (48.64) 205.64 (45.84) 201.75 (43.29) .078 22.5
Placebo Male (18) 237.89 (38.00) 239.61 (37.50) 246.07 (37.25) .369 5.7 .046
Ashwagandha Male (19) 217.80 (36.99) 200.19 (36.50) 200.70 (36.25) .071 13.7
Testosterone (ng/dL) Placebo All (30) 341.75 (50.61) NA 341.97 (53.42) .990
∗
0.0 .150
Ashwagandha All (30) 320.72 (50.61) NA 354.88 (53.42) .043
∗
13.3
Placebo Female (12) 39.18 (17.42) NA 38.68 (15.44) .864
∗
0.3 .965
Ashwagandha Female (11) 57.90 (18.20) NA 57.78 (16.13) .989
∗
0.0
Placebo Male (18) 543.47 (46.29) NA 544.17 (49.33) .980
∗
0.0 .158
Ashwagandha Male (19) 472.88 (45.06) NA 526.89 (48.01) .038
∗
21.8
∗
Paired samples ttest.
CORTISOL (mcg/dL)
16
15
14
13
12
11
10
9
Day 0 Day 30 Day 60
Time
Ashwagandha
DHEA-S (mcg/dL)
280
260
240
220
200
180
160
Day 0 Day 30 Day 60
Time
Testosterone (ng/dL)
400
380
360
340
320
300
280
260
Day 0 Day 60
Time
Placebo
Figure 3. Mean change in hormones (vertical bars depict standard error bars).
Lopresti et al. Medicine (2019) 98:37 Medicine
6
ashwagandha group and a 0% variability in the placebo group. A
comparison of between-group differences revealed a nonsignifi-
cant time x group interaction (F
1,35
=2.08, P=.158).
3.2. Adverse events and treatment compliance
Participants were questioned about capsule tolerability and
adverse events at days 15, 30, 45, and 60. Ashwagandha was well
tolerated with no significant adverse events reported by
participants. Good tolerability of ashwagandha intake was also
further confirmed by the ability and willingness of all participants
to complete the 60-day trial. Compliance with capsule intake was
also high as all participants consumed >90% of allocated
capsules (as measured by returned capsule count at days 15, 30,
45, and 60).
Pre and posthematological measures comprising a full blood
count (hemoglobin, white blood cell, neutrophils, eosinophils,
platelets, red blood cell, lymphocytes, and monocytes) and lipid
profile (total cholesterol, triglycerides, high-density lipoprotein,
low-density lipoprotein, and very-low-density lipoprotein) con-
firmed no statistically significant, between-group differences in
the measures over time.
4. Discussion
In this randomized, double-blind, placebo-controlled trial, the
60-day intake of an ashwagandha extract (Shoden) in mildly
anxious, healthy adults resulted in significant emotional improve-
ments over time. Compared with the placebo, ashwagandha
intake was associated with a statistically significant, greater
reduction in the HAM-A, although changes in the DASS-21 failed
to reach statistical significance, despite a strong positive trend.
Ashwagandha intake was also associated with greater reductions
in morning cortisol and DHEA-S; and a positive trend suggesting
an increase in testosterone concentrations (the latter evidenced in
men only). Ashwagandha was well tolerated with no significant
reports of adverse events or changes in hematological measures
(full blood count and lipid profile) over time.
Based on the HAM-A, anxiety levels reduced by 41% in
participants taking ashwagandha, which compared favorably to
the 24% reduction experienced in participants taking a placebo.
Further confirmation of the mood-enhancing effects of ashwa-
gandha was provided by positive overall improvements in the
DASS-21 (30% vs 10%), a measure of depressive, anxiety, and
stress symptoms. However, between-group differences in DASS-
21 changes did not reach statistical significance. These overall
positive anxiolytic and mood-enhancing effects of ashwagandha
are consistent with other previously published studies examining
the efficacy of other ashwagandha extracts in stressed adults.
[18–
22]
However, the dosage used in this study (240 mg, standardized
to be not less than 35% withanolide glycoside) was lower than
the 600mg dose most commonly used in previous studies.
To understand the therapeutic mechanisms of ashwagandha in
stressed adults, changes in the stress hormone, cortisol, and
steroidal hormones, DHEA-S and testosterone were measured.
The findings indicated that compared with placebo, ashwa-
gandha intake was associated with a reduction in fasting,
morning cortisol (0.5% increase and 23% reduction, respective-
ly) and DHEA-S (2.5% increase and 8.2% decrease, respective-
ly). Ashwagandha intake was also associated with a statistically
significant increase of 10.6%, in testosterone which compared
favorably to the 0.1% increase observed in the placebo group.
However, changes in testosterone between the ashwagandha and
placebo groups did not reach statistical significance.
Gender-wise analyses suggested ashwagandha had similar
effects on cortisol and DHEA-S in both males and females as
statistically significant changes occurred in both genders.
However, testosterone levels did not change significantly in
females after both ashwagandha (0.2% reduction) and placebo
(1.3% reduction) intake. In contrast, testosterone levels increased
in males by 11.4% following ashwagandha intake which
compared favorably to the 0.1% increase following placebo
intake. However, this difference was not statistically significant,
possibly due to the small sample size of 37 males and/or
differences in baseline testosterone levels between the treatment
conditions. Further investigation utilizing a larger sample size will
be required to clarify the significance of these testosterone
findings in men. Moreover, the clinical relevance of these changes
in testosterone requires further investigation. However, it is
helpful to consider that on average it has been reported that
testosterone levels reduce by 110ng/dL every 10 years in males
after the age of 30.
[28,29]
The increase of 54ng/dL occurring after
the 8-week administration of ashwagandha in our study suggests
that these changes may have health-related clinical benefits.
Based on our findings, the anxiolytic effects of ashwagandha
may be attributed to several mechanisms. First, ashwagandha
may have an attenuating effect on the hypothalamic-pituitary-
adrenal (HPA) axis activity. In response to a stressor, the HPA
axis is associated with a series of responses ultimately leading to
increases in both cortisol
[30]
and DHEA
[31,32]
concentrations.
While increased cortisol output has been commonly investigated
in human-stress studies, the impact of stress on DHEA has
received far less attention. Although higher DHEA is often
associated with increased health and longevity,
[33,34]
within the
context of stress its elevation may be an indicator of an increased
stress response (or HPA activity). For example, increased DHEA-
S secretion has been demonstrated in adults following acute stress
exposure,
[31,32]
and is higher in adults with posttraumatic stress
disorder, as confirmed by a recent meta-analysis.
[35]
Higher
levels are also associated with cigarette smoking and alcohol
consumption in middle-age men.
[36]
These findings suggest
elevated DHEA (along with cortisol) may be a marker of
increased stress. Its acute reduction may, therefore, be a sign of
stress reduction. Within the adrenal cortex, production of cortisol
and DHEA occurs in different layers, with cortisol produced in
the zona fasciculata and DHEA in the zona reticularis. Although
a regulatory negative feedback system is in place to ensure a
restoration in cortisol levels following a stressor, a significant
body of evidence suggests that anxiety and depressive disorders
are associated with disturbances in HPA axis activity, commonly
leading to an excess in cortisol secretion.
[37]
The reduction in
morning cortisol and DHEA-S in participants taking ashwa-
gandha suggest it has a moderating effect on HPA axis activity in
stressed adults. This may be associated with stress-lowering
effects as the stress response (or HPA axis activity) becomes less
reactive to stressors.
Although not investigated in this study, other potential
mechanisms of ashwagandha’s anxiolytic effects may be via it
antioxidant and anti-inflammatory effects.
[38,39]
Inflammation
and oxidative stress are increased during times of high stress, and
higher levels have been demonstrated in adults with depression
and anxiety.
[40,41]
In preclinical studies, ashwagandha can also
influence GABAergic
[42]
and serotonin activity,
[8,43]
which have
antidepressant and anxiolytic effects. Moreover, despite these
Lopresti et al. Medicine (2019) 98:37 www.md-journal.com
7
mechanisms being discussed separately, their effects do not occur
in isolation and it is likely that the interaction of all these
mechanisms may be responsible for the positive, mood-enhancing
effects of ashwagandha.
4.1. Study limitation and directions for future research
Although findings from this study add to the body of evidence
supporting the antistress effects of Ashwagandha, there remain
several unanswered questions. In this study, healthy adults with
mild stress were recruited. The effects of ashwagandha in clinical
populations suffering from an anxiety or other affective disorder
remain to be determined. However, positive anxiolytic effects of
ashwagandha in adults with generalized anxiety disorder have
been identified in previous studies.
[18,19]
Moreover, most of the
studies on the anxiolytic effects of ashwagandha, including ours,
have been conducted in India. Future studies with other cultural
populations may, therefore, be useful. We also did not examine
the impact of feeding habits, economic conditions, and daily
occupation on the anti-stress effects of ashwagandha. These may
have an influence on therapeutic outcomes so would be worth
examining in future studies.
In this study, the effects of ashwagandha were examined over a
60-day duration, which is consistent with most studies. Longer
studies should be undertaken to examine the safety and efficacy of
ashwagandha supplementation over a longer period. Follow-up
after intake cessation will also be helpful to identify if there are
any withdrawal issues and whether positive changes are sustained
over time once supplementation is ceased.
In the 6 studies that have now examined the anxiolytic effects
of ashwagandha, varying ashwagandha extracts, using different
extraction techniques and standardization methods, have been
used. Overall, the findings have been positive; however, the
relative safety and anxiolytic potency of these different extracts
are yet to be examined. This may be of interest in future trials.
Moreover, dosages used across trials have varied significantly
making it difficult to decipher optimal therapeutic doses. Dose-
escalation studies for nonresponders and dose-response effects
may also be of interest. In a study by Auddy et al,
[20]
greater dose-
response effects were identified in chronically stressed adults.
Finally, we examined the physiological impact of ashwa-
gandha supplementation in stressed adults and identified several
changes in hormones associated with the adrenal and steroidal
system. Given the small sample size recruited in our study, we
were unable to examine the relevance of such changes for
symptom resolution. In future trials, it will not only be important
to examine physiological changes associated with ashwagandha
supplementation, but also to determine whether such changes are
related to symptomatic changes. This will help us develop clearer
hypotheses about ashwagandha’s anxiolytic mechanisms of
action. Moreover, further investigation into the effects of
ashwagandha on other hormones such as pregnenolone,
oestrogens, and progesterone; and examinations into gender
differences will be useful.
In conclusion, the findings from this study support the positive
anxiolytic effects of a novel ashwagandha extract (Shoden,
standardized to not less than 35% of total glycowithanolides)
taken for 60 days at a dose of 240 mg daily. Statistically
significant, between-group differences were confirmed by 1 mood
measure (HAM-A), while a strong positive trend was observed
for the DASS-21 measure. The ashwagandha extract was well-
tolerated with no reported significant adverse effects. Supple-
mentation was associated with a reduction in cortisol and DHEA-
S, and a positive, although nonsignificant trend of increased
testosterone in men. These results suggest the anxiolytic effects of
ashwagandha in stressed adults may be associated with an
attenuating effect on HPA axis activity and, in men, increased
testosterone production. However, there are potentially addi-
tional mechanisms of action that were not investigated in our
study. Further clinical trials are warranted using larger sample
sizes, differing cultural populations, and longer durations to
substantiate our findings and those from previously conducted
trials.
Acknowledgment
The authors gratefully acknowledge Arjuna Natural Ltd for
funding the project and supplying Shoden for use in this study.
Author contributions
Conceptualization: Hakeemudin Malvi, Rahul Kodgule.
Data curation: Rahul Kodgule.
Formal analysis: Adrian Lopresti, Stephen J Smith.
Funding acquisition: Rahul Kodgule.
Investigation: Hakeemudin Malvi, Rahul Kodgule.
Methodology: Adrian Lopresti, Stephen J Smith, Hakeemudin
Malvi, Rahul Kodgule.
Project administration: Hakeemudin Malvi, Rahul Kodgule.
Writing –original draft: Adrian Lopresti, Stephen J Smith.
Writing –review & editing: Adrian Lopresti, Stephen J Smith,
Hakeemudin Malvi, Rahul Kodgule.
Adrian Lopresti orcid: 0000-0002-6409-7839.
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