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- Ashwagandha (Withania somnifera)
- Mental Stress
- Cardiovascular Health
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Date:
10-31-2014 | HC# 051456-507
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Re: Ashwagandha May Reduce Stress-induced Cardiovascular Changes in Healthy Males; More Study Is Needed
Pingali
U, Pilli R, Fatima N. Effect of Withania
somnifera extract on mental stress induced changes in hemodynamic
properties and arterial wave reflections in healthy subjects. Curr Top Nutraceutical Res.
2013;11(4):151-158.
Mental
stress adversely affects the circulatory system and cardiovascular health, and
impairs the body's antioxidant defense system. Ashwagandha (Withania somnifera) is used in Ayurvedic
medicine to help the body adapt to stress. It is also used to promote physical
and mental health. The purpose of this randomized, placebo-controlled,
double-blind, crossover study was to evaluate the effect of ashwagandha on
cardiovascular and hemodynamic responses to mental stress in healthy male subjects.
Healthy
men (n = 20, mean age 25 years) participated in this study conducted in
Panjagutta, Hyderabad, India. The inclusion criteria were as follows:
nonsmoker; nonobese (body mass index <23 kg/m2); no hypertension,
diabetes, or hyperlipidemia; and not taking antioxidant vitamin supplements for
the prior 3 months. Subjects abstained from caffeine and alcohol for 24 hours
prior to and during the test days and were trained on ≥ 2 occasions on the
study procedures. Subjects received either placebo or 1,000 mg/day (500 mg twice
daily) aqueous ashwagandha root and leaf extract (Sensoril®; Natreon
Inc.; New Brunswick, New Jersey) for 14 days. The ashwagandha extract was
prepared from a genetically uniform withaferin A and withanolide
glycoside-dominant chemotype grown in the northern and central provinces of
India. The extract was standardized to contain not less than 10% withanolide
glycosides, not more than 0.5% withaferin A, and not less than 32%
oligosaccharides. The identical placebo capsules contained microcrystalline cellulose,
lactose, and magnesium stearate.
At
baseline and 3 hours after dosing on day 15, blood pressure, heart rate,
arterial stiffness, augmentation index, and augmented pressure of the central
(aortic) pressure waveform were measured before and 2 min after the mental
stress test was performed. The mental stress test consisted of the following computerized
psychometric tests: choice discrimination test, digit symbol substitution test,
and digit vigilance test. Blood was drawn before and after each test to measure
high-sensitivity C-reactive protein (hs-CRP), cortisol levels, and safety
parameters. Following a 14-day washout period, the subjects were crossed over
to the other treatment and the protocol was repeated.
In
the placebo group, mental stress increased blood pressure, but did not increase
heart rate compared with baseline. According to the authors, post-treatment and
post-stress, compared to the placebo group, the ashwagandha group had lower
aortic pressure (P < 0.001), augmentation index (P < 0.05),
subendocardial viability ratio (an indicator of myocardial perfusion, P <
0.05), radial systolic blood pressure (P < 0.05), radial diastolic blood
pressure (P < 0.01), radial mean pressure (P < 0.01), aortic systolic
blood pressure (P < 0.01), aortic diastolic blood pressure (P < 0.01),
aortic mean pressure (P < 0.01), and aortic pulse pressure (P < 0.01). Hs-CRP,
which is known to increase with stress, was significantly decreased following
stress in the ashwagandha group vs. placebo group (P < 0.01). Cortisol and malondialdehyde
(MDA) levels, which increase with stress, were decreased following stress in
the ashwagandha group vs. placebo group (P < 0.05 and P < 0.01,
respectively), according to the authors. The blood analyses showed that none of
the treatments affected safety parameters.
The
authors conclude that ashwagandha "can ameliorate the negative change in
cardiovascular parameters associated with mental stress." Ashwagandha had
a beneficial effect on arterial function by reducing aortic stiffness, wave
reflections, and aortic pulse pressure. Also, the decrease in MDA levels
supports the hypothesized in vivo antioxidant effect of ashwagandha. However,
since the subjects were all healthy young males, the results cannot be
generalized to consumers at large.
In
the text of the article, it is stated that the changes in the ashwagandha group
were significant compared to both baseline and placebo (except for the changes
in blood pressure which were said to be significant only in comparison to
placebo). However, the data indicating the statistical significance of the
changes between pre- and post-placebo and pre- and post-ashwagandha treatment measures
(pairwise comparison P-values; the purported purpose of the study) are not
presented. It is not clear why the authors chose instead to report P-values for
non-pairwise comparisons in the data tables (i.e., comparing post-stress
pretreatment measures in the placebo group with post-stress post-treatment measures
in the ashwagandha group). In addition, the authors do not report any
statistical adjustments for multiple comparisons and therefore the reported
significant differences may be biased.
These
preliminary results may have been over-interpreted by the authors. Additional
studies with larger sample sizes and much more rigorous statistical analyses
and reporting are needed to corroborate the results.
—Heather S. Oliff,
PhD
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