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THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE
Volume 13, Number 10, 2007, pp. 1085–1090
© Mary Ann Liebert, Inc.
Improvement of Glutathione and Total Antioxidant
Status with Yoga
SANCHARI SINHA, M.Sc.,
SOM NATH SINGH, Ph.D.,
Y.P. MONGA, M.S.,
and UDAY SANKAR RAY, Ph.D.
Objective: Several studies suggest that yoga can decrease oxidative stress. However reports are scanty re-
garding whether yoga training can improve the glutathione level of individual. This study is designed to ap-
praise the role of yoga in maintaining glutathione (reduced and oxidized) levels and antioxidant status.
Study design: This study was conducted on healthy male volunteers from the Indian Navy, who were di-
vided into two groups—a yoga (n 30) group and a control (n 21) group. The yoga group was trained in
yoga for 6 months. The yoga schedule consisted of prayers, asana, pranayama, and meditation. The control
group practiced routine physical training exercise for 6 months. Blood samples were collected when the vol-
unteers were in fasting condition before and after completion of 6-month training period. Reduced and oxidized
glutathione, glutathione reductase activity and total antioxidant status (TAS) were estimated.
Results: Reduced glutathione level increased significantly (p 0.05) in the yoga group after completion of
training. Glutathione reductase activity increased significantly in the control group (p 0.05). TAS increased
significantly (p 0.001) in the yoga group and decreased significantly (p 0.001) in the control group.
Conclusions: Regular practice of yoga can maintain or improve antioxidant level of the body. The clinical
relevance is that yoga practice can be used to maintain the antioxidant defense system under stressful condi-
tions of training as observed in the case of soldiers and athletes.
oga is known for its beneficial effects on physiologic
and psychologic functions.
During the last 3 decades,
extensive physiologic research have been done on yogic
practices. It has been reported that yoga can increase mus-
cular efficiency, endurance time
and aerobic capacity, and
can reduce perceived exertion after exercise.
is widely used as a stress reliever.
has a profound effect on the autonomic nervous system
and may reduce stress levels in individuals
via this effect. Regarding oxidative stress, reports have sug-
gested that yoga can decrease oxidative stress,
the malonaldehyde (MDA) level, and increase superoxide
dismutase (SOD) and catalase activity.
Various reports re-
garding aerobic exercise training propose that mainly cata-
lase activity is increased by training
but exercise training
is not sufficient to maintain the redox status of the body.
There is growing evidence that supports the beneficial ef-
fect of yoga on antioxidant enzymes. But reports regarding
the role of yoga on glutathione (a major antioxidant tripep-
tide) level in reducing oxidative stress are scanty. Therefore
the present study was undertaken to evaluate the effect of
yoga on glutathione level and total antioxidant status (TAS).
MATERIALS AND METHODS
The study was conducted on healthy male volunteers of
the Indian Navy belonging to various branches (i.e., ship,
Defence Institute of Physiology and Allied Sciences, Delhi, India.
Indian Naval Hospital Ship, (INHS) Kalyni, Mumbai, India.
submarine, aviator, etc.). Initially, 60 volunteers were ran-
domly selected from the personnel of the Indian Navy. The
volunteers were briefed about the study protocol approved
by the ethical committee of the Defence Institute of Physi-
ology and Allied Sciences, Delhi, India, and written consent
was obtained from each volunteer. Then the volunteers were
divided into two groups: a yoga group and a control group.
The yoga group consisted of 30 volunteers (age: 32.8 1.4
yrs; height: 168.8 .9 cm; weight: 65.2 1.5 kg) and the
control group consisted of 21 volunteers (age: 25.5 1.6
yrs; height: 170.1 0.9 cm; weight: 62.7 1.8 kg). Ini-
tially, there were 30 volunteers in each group, but 9 volun-
teers dropped from the control group and could not continue
the entire 6 months of training. Thus, the control group com-
pleted the study with 21 volunteers. As the volunteers had
free choice to select which group to be in, the majority of
the older persons among the volunteers preferred to do yoga,
as this is a comparatively lower-intensity form of exercise.
Thus, the mean age of the yoga group was comparatively
higher (p 0.05) than that of the control group. For this
reason, each group was compared individually at baseline
and after 6 months.
Twenty Naval personnel of the Eastern Naval Command
were chosen for training as yoga instructors. The profes-
sional instructors of the Kaivalyadhama Institute, Lonavala,
Maharastra, India, trained the personnel in yoga for 2
months. The training schedule included practical asanas and
theory lectures. The trainers taught both theory and practical
aspects of yoga and its benefits to the volunteers (Table 1).
The yoga group underwent yogic training, for 1 hour in
the morning, 5 days per week for 6 months. The yoga sched-
ule consisted of prayers, asanas, pranayama, and medita-
tion. Each asana was performed for 1–2 minutes’ duration
(Table 2). At the end of the asana, various breathing ma-
neuvers (pranayama) were performed for 5–10 minutes.
Pranayama included deep breathing, inhalation-retention-
exhalation with a ratio of 1:1:2, abdominal (diaphagramatic)
breathing, and alternate nostril breathing. Breathing exer-
cises were recommended immediately after practicing
asanas. This was then followed by meditation for 5 min-
utes. Meditation was a component of Patanjali’s Astanga
yoga. During meditation the individuals sat in a comfortable
posture (either Sukhasana or padmasana) with eyes closed
and tried to feel completely relaxed. First, the subjects fol-
lowed the usual wandering mind/thought process that allows
the mind freedom. Later, slowly, they tried to be aware of
their surroundings. Subsequently, the subjects tried to pay
attention, slowly, to different body parts from toe to head
and, ultimately, to the breathing process (i.e., awareness of
a normal breathing cycle). After this the subjects chanted
the Omkar Mantra (the syllable AUM) and tried to feel the
presence of the Almighty. The pattern was, to some extent,
similar to a meditation technique mentioned in a paper by
Wallace and Benson.
The control group practiced routine
physical training (PT) exercises during the same period. The
PT schedule (total 1 hour) included slow running up to 4
km (30 minutes), body-flexibility exercises (10 minutes),
pull ups (5 minutes), and games (15 minutes). On comple-
tion of 1 hour of daily training, both groups returned to their
SINHA ET AL.
Practical asanas—2 hrs
Theory lectures—3 hrs
Practical asanas—1 hrs
1 month 2 months
Ardha Halasana with one leg 3 times Halasana
Pavan Muktasana with one leg 3 times Pavan Muktasana
Bhujanganasana Crocodile poses
Shalabhasana with one leg Paschimtanasan
Pada hastasan Setubandasan
Brahma Mudra Vrikshasan
Yoga Mudra Santulasan
Anuloma Viloma Utkatasan
Kapalbhati Agnisar Kriya
Bandhas—Moll band uddiya, Jalandar
normal daily routines in their respective units. This routine
PT schedule was followed by both of the groups before the
commencement of the 6 month training schedule.
Collection of samples
Fasting blood samples were collected when the volun-
teers were in resting condition in the morning hours (at
) before and after completion of 6 months of
training and analyzed for reduced glutathione (GSH), oxi-
dized glutathione (GSSG), glutathione reductase (GR), ac-
tivity, and TAS.
For the estimation of GSH and GSSG, blood samples
were collected in 10% (w/v) metaphosphoric acid and
estimated using the fluorimetric method of Hissin and
This method measures both GSH and GSSG with an
o-phthalaldehyde (OPT) as a fluorescent reagent. Briefly,
metaphosphoric acid-treated whole blood was centrifuged
and the supernatant was treated with OPT at a pH of 8 and
estimated for GSH using a fluorescence spectrophotometer
with an excitation and emission wave lengths of 350 nm and
420 nm. The same process was followed for GSSG at pH
12. For estimating GSSG, GSH can be complexed to N-
ethylmaleimide to prevent interference of GSH with the
measurement of GSSG.
To measure GR activity, whole blood was taken in an
EDTA (ethylenediaminetetraacetic-acid)-treated vial and a
10% lysate of whole blood was prepared to measure the
activity spectrophotometrically by the method of Racker.
Via this method, lysate was incubated with GSSG and
NADPH (nicotinamide adenine dinucleotide phosphate re-
duced) at a pH 7.5 and changes in optical density were mea-
sured at 340 nm for 3 minutes at an interval of 30 seconds.
The results were expressed as mol of NADPH oxidized
per minute per mL of lysate.
TAS was measured as an ABTS (2,2-azino-di[3-ethyl-
benzthiazoline sulphonate) radical cation decolorizing assay
using a Randox kit (Cat No. NX 2332) (Randox Laborato-
ries Ltd., Ardmore, U.K.).
Statistical analysis of the work was carried out by a Stu-
dent’s paired t test.
In the yoga group, GSH level increased significantly (p
0.05) from the baseline value of 235.3 16.9 nmol/L to
331.7 37.6 nmol/L after completion of training. In the
control group, the GSH level decreased. Values of GSSG
decreased in the yoga group and increased in the control
group. The ratio of GSH/GSSG increased significantly (p
0.001) from the pretraining value of 0.88 0.02 to 1.34
0.04 in the yoga group. In the control group, this ratio did
not decrease significantly. GR activity increased signifi-
cantly (p 0.05) from baseline value of 0.82 .05
mol/mL/min to 0.98 0.06 mol/mL/min after comple-
tion of training in the control group. TAS significantly (p
0.001) increased from the pretraining value of 1.23 .04
mmol/L to the post-training value of 1.96 0.03 mmol/L
in the yoga group and decreased significantly (p 0.001)
from the pretraining value of 1.37 0.05 nmol/L to the
post-training value of 1.06 0.04 nmol/L in the control
group. Comparisons of various parameters between the two
groups are presented in Table 3.
GSH is a very important substrate for antioxidant defense
system and is used by glutathione peroxidase as a donor of
a hydrogen atom to reduce hydrogen peroxide (H
An increased amount of GSH is very helpful for an
antioxidant defense mechanism that reduces oxidative
GSH is oxidized to GSSG in cells in response to
an increase in free radicals in a state of oxidative stress.
It is well-recognized in the literature that acute bouts of ex-
ercise can change the glutathione redox status of the cells
toward an oxidized state (i.e., a decrease in GSH level and
an increase in GSSG level).
In the case of training, re-
ports suggest that aerobic training can increase the produc-
tion of oxygen-free radicals and that oxidative stress is likely
because of electron leakage at intermediary steps in the elec-
YOGA AND ANTIOXIDANTS
Duration: 1 hour
1st month 2nd–6th months
Ardha Halasana Kapalbhati—2 minutes
Pavan Muktasana Surya Namaskar—2 rounds
Bhujanganasana Asanas (30 minutes)
Parvatasana Yoga Mudra
Yoga Mudra Karmapadasana
Pranayama (15 minutes)
Parameters Baseline After 6 months p-value
GSH (nmol/L) 235.3 16.9 331.65 37.6 p 0.05
GSSG (nmol/L) 263.2 9.4 255.8 10.8 Not significant
GSH/GSSG 0.88 0.02 1.34 0.004 p 0.001
GR activity 0.89 0.05 0.88 0.05 Not significant
TAS (mmol/L) 1.23 0.04 1.96 0.03 p 0.001
Parameters Baseline After 6 months p-value
GSH (nmol/L) 328.1 28.5 288.6 18.7 Not significant
GSSG (nmol/L) 294.3 9.3 314.6 18.5 Not significant
GSH/GSSG 1.19 0.07 0.98 0.12 Not significant
GR activity 0.82 0.05 0.98 0.06 p 0.05
TAS (mmol/L) 1.37 0.05 1.06 0.04 p 0.001
Value: Mean standard error of the mean.
GSH, reduced glutathathoine; GSSG, oxidized glutathione; GR, gluthathione reductase; TAS, total antioxidant status.
Comparison of GSH status in yoga and control group
at baseline and after 6 months of training
Comparison of GSSG status in yoga and control group
at baseline and after 6 months of training
Comparison of GR activity in yoga and control group
at baseline and after 6 months of training
Comparison of TAS in yoga and control group
at baseline and after 6 months of training
FIG. 1. Comparison of the levels of reduced glutathione (A), oxidized glutathione (B), and glutathione reductase (C), as well as to-
tal antioxidant status (D) in the yoga and control groups. Phase I is before training. Phase II is after 6 months of training. *p 0.05;
tron-transport chain. Over the past decade, numerous stud-
ies examined exercise training as an oxidative stressor to
evaluate the ability of the body to respond to the potential
oxidative stress of training via positive adaptation to its an-
tioxidant defense. However, there was a lack of antioxidant
adaptation to aerobic and anaerobic training at substrate
level in humans.
Similarly, our results did not show this
kind of positive adaptation in the control group after 6
months of training. Proper positive adaptation might depend
on the intensity and duration of training used. These results
suggest that the aerobic training to which volunteers were
exposed might not be sufficient enough to induce positive
In this study, we have seen that GSH level increased sig-
nificantly in the yoga group (p 0.05) and decreased in the
control group. However, GSSG levels decreased in the yoga
group and increased in the control group but these changes
were not significant. This suggests that redox status can be
shifted toward a reduced state by practicing yoga, which is
an important adaptative strategy for minimizing oxidative
stress and its effects. GSH/GSSG ratio is another important
and sensitive marker of the antioxidant system. This ratio
increased significantly in the yoga group, which confirms
further the beneficial effect of yoga training on the antiox-
idant system. A decreased GSH/GSSG ratio in the control
group indicated a decrease in the reductive capacity of the
red blood cells.
Generally, aging persons are more susceptible to oxida-
tive stress. In this study, in spite of the subjects of the yoga
group being comparatively aged (32.8 1.4 yrs) than the
control group (25.5 1.6 yrs), the yoga group had a better
capacity to combat oxidative stress. This reaffirms that yo-
gic practices help in the management of oxidative stress.
Among antioxidant enzymes, GR is a primary enzyme for
maintaining glutathione redox status. It converts GSSG to
its reduced state (GSH). In the process of reduction GR uses
NADPH as a hydrogen donor.
Previous reports proposed
enhancement in GR activity after exercise.
also showed the same trend. Here, in the control group GR
activity increased significantly as a result of increased avail-
ability of its substrate (i.e., GSSG). But this increased GR
activity was not sufficient enough to maintain the body mi-
lieu in a reduced state, as a result GSSG levels were still high
in the control group. However, decreased levels of GSSG and
GR activity in the yoga group again showed a positive re-
sponse to yoga on the part of the antioxidant system.
TAS of a cell represents overall antioxidant capacity of
the cell. It has been suggested that oxidative stress occurs
during physical exercise.
In this study, significant in-
crease in TAS in the yoga group clearly showed a marked
improvement of overall cellular antioxidant level. However,
significant reductions in TAS in the control group showed
diminished antioxidant capacity, an effect that makes an in-
dividual affected more by the deleterious effects of oxida-
To achieve better comprehension we did intergroup com-
parisons and these also showed a supportive result for the
yoga group. In the GSH value at baseline, there was a
marked difference (p 0.001) between the two groups and
the redox status was much better in the control group, which
had higher GSH levels. This could be attributed to the young
age of the subjects in that group. But this trend reversed af-
ter 6 months of yoga training. Yoga augmented the GSH
levels significantly (p 0.05) in the yoga group compared
to the control group. For GSSG, there was no such signifi-
cant difference at baseline between the two groups. But af-
ter training, GSSG levels increased significantly (p 0.001)
in the control group in contrast to the yoga group. GR ac-
tivity also showed a similar trend. TAS value was moder-
ately higher in the control group almost approaching sig-
nificance (p 0.07) at baseline. But after yoga training, an
enormous raise in TAS value was seen in the yoga group
(p 0.001) compared to the control group. All these results
are clearly evidence of the fact that, despite being older, vol-
unteers in the yoga group had better antioxidant adaptation
after performing 6 months of training.
According to the findings of this study, it may be con-
cluded that yoga may upregulate the antioxidant capacity of
cells to combat oxidative stress.
The authors are grateful to the director of the Defence In-
stitute of Physiology and Allied Sciences (DIPAS), Delhi,
India, for giving necessary permission for this study to be
performed. We are thankful to the Integrated Head quarters,
in the Ministry of Defence (DGMS-Navy) for encouraging
the work. We are also grateful to Surg. Cdr. Marys Joseph,
at INHS Kalyani, and the staff members of the INHS
Kalyani, Mr. O.S Tomer, Technical Officer “B,” DIPAS,
Delhi, for their kind help in the successful completion of the
study. We are sincerely thankful to Dr. Y.K. Sharma, Sci-
entist “E,” at DIPAS, Delhi for statistical analysis. Last but
not least, we are thankful to all the volunteers from the INHS
Kalyani who were the subjects for this study.
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Address reprint requests to:
Uday Sankar Ray, Ph.D.
Defence Institute of Physiology and Allied Sciences
Timarpur, Delhi 110054
SINHA ET AL.