Complementary Therapies in Medicine (2013) 21, 571—576
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/ctim
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes: A randomized controlled trial夽 Shreelaxmi V. Hegde a,∗, Prabha Adhikari b, Sowmya Shetty c, Poornima Manjrekar d, Vivian D’Souza d a
Department of Biochemistry, Srinivas Institute of Medical Science and Research Centre, Mangalore, India Department of Medicine, Kasturba Medical College and Hospital, Manipal University, Mangalore, Karnataka, India c Department of Community Medicine, Srinivas Institute of Medical Science and Research Centre, Mangalore, India d Departmentof Biochemistry, Kasturba Medical College and Hospital, Manipal University, Mangalore, Karnataka, India Available online 9 September 2013 b
KEYWORDS Prediabetes; Yoga; Oxidative stress; Antioxidants; Glycated haemoglobin
Summary Objectives: To study the effectiveness of yoga intervention on oxidative stress, glycemic status, blood pressure and anthropometry in prediabetes. Design: Randomized-controlled trial. Participants: Twenty nine prediabetes subjects aged 30—75 years. Setting: Yoga was conducted at 4 different community diabetes clinics in Mangalore, India. Interventions: Participants were randomized to either 3-month yoga or wait-list control groups. Main outcome measures: Malondialdehyde, glutathione, vitamin C, vitamin E, superoxide dismutase, plasma glucose, glycated haemoglobin, BMI, waist circumference, waist-to-hip ratio and blood pressure. Results: Yoga intervention resulted in a significant decline in malondialdehyde (p < 0.001), relative to the control group. In comparison with the control, there was a significant improvement in BMI, waist circumference, systolic blood pressure and fasting glucose levels at follow-up. No significant improvement in glycated haemoglobin, waist-to-hip ratio or any of the antioxidants was observed.
夽
This study was funded by Manipal University. Corresponding author at: Department of Biochemistry, Srinivas Institute of Medical Science and Research Centre, Mukka, Mangalore 574021, Karnataka, India. Tel.: +91 824 2425966; fax: +91 824 2442766; mobile: +91 9986668611. E-mail address: [email protected] (S.V. Hegde). ∗
0965-2299/$ — see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ctim.2013.08.013
572
S.V. Hegde et al. Conclusions: Yoga intervention may be helpful in control of oxidative stress in prediabetes subjects. Yoga can also be beneficial in reduction in BMI, waist circumference, systolic blood pressure and fasting glucose. Effect of yoga on antioxidant parameters was not evident in this study. The findings of this study need to be confirmed in larger trials involving active control groups. © 2013 Elsevier Ltd. All rights reserved.
Introduction The incidence of type 2 diabetes mellitus is increasing worldwide. Type 2 diabetes results from various factors like genetic predisposition, environmental and lifestyle risk factors.1 Lifestyle factors such as physical inactivity and dietary changes are the strongest modifiable risk factors in the prediabetes group which progresses them to the stage of diabetes.2,3 Prediabetes is a collective term for people with impaired glucose tolerance and/or impaired fasting glucose.4 Oxidative stress is a steady-state level of reactive oxygen radicals in a biological system. It may result from overproduction of oxygen radicals and/or decreased efficiency of antioxidant system. Non-enzymatic glycosylation, glucose auto-oxidation and polyol pathways are some of the biochemical pathways associated with hyperglycemia in diabetes mellitus leading to oxidative stress.5 Recent studies reveal that oxidative stress is also one of the pathogenic factor leading to insulin resistance, impaired glucose tolerance and ultimately to type 2 diabetes.6,7 Furthermore, macrovascular disease and its risk factors are often already present in this high risk group of developing type 2 diabetes.8 Hence lifestyle interventions designed to reduce oxidative stress in prediabetes may be useful in preventing their progression to type 2 diabetes. Yoga is found to be one of the effective non pharmacological intervention in reducing oxidative stress in type 2 diabetes.9—12 So far, interventions involving dietary change and increased physical activity to bring about weight loss and delay the onset of diabetes are encouraged in prediabetes subjects.13—15 But exercise therapy is a well-recognized model of OST as it increases the stress parameters.16,17 Two mechanisms have been documented to show increase in oxidative stress parameters after exercise, one by increase in oxygen consumption during exercise leading to disturbance of intracellular pro-oxidant-antioxidant homeostasis.18 Second mechanism is by increase in intracellular free radical generation in xanthine oxidase and electron transport chain.16 With this background in the present study we evaluated the effect of 3 months yoga on OST, antioxidant status, glycemic control, blood pressure and anthropometry in subjects with prediabetes.
Methods Recruitment The study was conducted during 2007 and 2008 at Kasturba Medical College Hospital (KMCH), Mangalore, India. Participants were recruited by conducting camps for detection of diabetes through media advertisements. Approval from the institutional ethical committee was taken prior to the study. All participants gave written informed consent. On
the day of the camp (visit 1) all the participants underwent fasting blood glucose and an oral glucose tolerance test (75 g of anhydrous glucose in 250 ml of water). Impaired fasting glucose was defined as fasting plasma glucose concentrations between 100 and 125 mg/dl (5.6—7.0 mmol/L) after an overnight fast. Impaired glucose tolerance was defined as plasma glucose concentrations between 140 and 200 mg/dl (7.8—11.0 mmol/L) 2 h after the oral glucose tolerance test. A lecture session on-role of diet, exercise and yoga in preventing the incidence of type 2 diabetes in prediabetes was conducted by the researcher. Finally 29 subjects were eligible for the study (Fig. 1). Non-alcoholics and non-smokers between the age of 30 and 75 years were only included for the study. Criteria for exclusion were a diagnosis of diabetes mellitus or any other diseases with elevated oxidative stress like cancer, pulmonary tuberculosis, rheumatoid arthritis, history of osteoporosis and infection. Eligible subjects were called for visit 2 during which they were randomized to the intervention group or the control group by means of a computer-generated randomization list. The study was not blinded.
Interventions Yoga centres were located at KMCH and at 4 community diabetes clinics offering primary care to diabetes patients in Mangalore city. Patients in the intervention group were given the choice to select any one of the yoga centre where they would practice yoga for the next 3-months. Yoga sessions consisted of 75—90 min each day interrupted by a two day weekend break for 3-months. Everyday yoga sessions began with asanas, followed by pranayama and shavasana.19 The list of asanas performed are given in Table 1. Compliance to the yoga classes was defined as attendance for atleast 3 days/week at the yoga centre for 3-months as documented by the yoga instructor. Subjects in the control group were the wait-list control group. Participants of both the groups were telephoned monthly by the researcher to monitor their adherence, improve their enthusiasm and to assist with any problems encountered with the study.
Outcome measures Outcome measures were assessed at baseline (visit 2) and 3-months. All study subjects completed a medical history questionnaire and underwent a physical examination that included anthropometric and blood pressure measurements according to standardized routines. Seven ml of venous blood was collected in EDTA and flouride tubes and immediately centrifuged to separate cells and plasma. Plasma was analysed for glucose, vitamin C and vitamin E. From the packed cells, red blood cell hemolysates were prepared to analyse malondialdehyde, reduced glutathione and superoxide dismutase (SOD) levels.
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes
Figure 1
573
Flow diagram for the trial: yoga intervention vs control.
Malondialdehyde, a product of lipid peroxidation was measured according to Stocks and Dormandy.20 Malondialdehyde reacts with thiobarbituric acid reagent in acidic medium to give pink colour at 97 ◦ C. The absorbance of the coloured product was estimated at 535 nm using a spectrophotometer. Reduced glutathione was determined by the method of Beutler et al.21 which is based upon the development of yellow coloured complex when 5,5 -dithiobis-2-nitrobenzoic acid reacts with sulfhydryl compounds. Activity of SOD was measured by Beauchamp and Fridovich method.22 Inhibition of reduction of nitroblue tetrazolium by superoxide radicals generated during the reaction was used as the basis for the assay of SOD. Vitamin C was estimated by 2,4-dinitro phenyl hydrazine.23 The method followed for estimation of vitamin E was that of Bieri et al.24 Tocopherols and carotenes were first extracted into petroleum ether and the absorbance was read at 460 nm to measure the carotenes. A correction was made for this after adding ferric chloride and read at 520 nm. Plasma glucose was measured by glucose oxidase method and glycated haemoglobin (HbA1 c) by particle enhanced immunoturbidimetric method using Dia Sys diagnostic kits, Holzheim, Germany in Hitachi 917 random access chemistry analyser.
Statistical analysis Analysis of endpoints was based on the principle of intention-to-treat using statistical package for social sciences (SPSS), version 16.0. Statistical analysis was done using ANCOVA taking baseline measurement of all the parameters (0 month) as a covariate and the measurement at 3 month being taken as dependent variable with fixed factor as the group (yoga and control). F value along with the descriptive that is mean, SD and CI were reported. A p-value of less than 0.05 was considered as statistically significant.
Results All 29 subjects completed the study. The study population comprised of impaired fasting glucose (5 no), impaired glucose tolerance (17 no) and impaired fasting glucose plus impaired glucose tolerance (7 no) subjects. No adverse events were observed during the intervention period. Average attendance at the yoga classes was 90%. The mean (±SD) age in yoga group was 46.50 (±13.03) years and 44.67 (±9.57) years in the control group (Table 2). Number of males/females recruited for the study was 6/8 in yoga
574
S.V. Hegde et al.
Table 1 Set of asanas and pranayama included in the yoga intervention. Sanskrit
English
Tadasana Padahastasana Vrikshasana Trikonasana Parshvothanasana
Mountain pose 2 min Forward bend pose 3 min Tree pose 3 min Triangle pose 3 min Extreme sideways 3 min stretch pose Thunderbolt pose 3 min Twist pose 4 min Cow-faced pose 4 min Seated forward 4 min bend pose Raised feet pose 4 min Wind relieving pose 5 min Cobra pose 3 min Locust pose 3 min Bow pose 3 min Inverted action pose 4 min Teeth hissing 8 min Bee breathing 6 min Alternate nostril 10 min breathing Corpse pose 10 min
Vajrasana Vakrasana Gomukasana Paschimotasana Uttanapadasana Pawanamuktasana Bhujangasana Shalabasana Dhanurasana Viparitakarani Sitkari pranayama Bhramari pranayama Anuloma viloma Shavasana
Time duration
intervention and 8/7 in control group. Measurements like BMI, waist circumference, waist-to-hip ratio, blood pressure, fasting plasma glucose, post prandial plasma glucose, HbA1 c, malondialdehyde and antioxidants were comparable at baseline. Yoga intervention in prediabetes significantly reduced BMI, waist circumference, systolic blood pressure and fasting plasma glucose levels (Table 3). There was a significant improvement in malondialdehyde and SOD levels. There was no significant improvement in waist circumference, post prandial plasma glucose, HbA1 c and other antioxidants.
Discussion Principle finding The present study demonstrates that yoga intervention in prediabetes can significantly reduce oxidative stress as evidenced by malondialdehyde and superoxide dismutase levels. In this study the participants in yoga group showed a marginal reduction in other variables like BMI, waist circumference, fasting glucose and systolic blood pressure. Prediabetes is an intermediary stage between normal glucose tolerance and decreased tolerance to glucose as in type 2 diabetes mellitus. Studies reveal that this mild increase in blood glucose in prediabetes can result in oxidative stress.6,25 Thus there is a gradual rise in oxidative stress from the stage of prediabetes to diabetes without complications and with various complications.6 Many of the controlled trials in type 2 diabetes have shown improvement in oxidative stress markers and glycemic control after yoga intervention.9—12 The duration of yoga intervention delivered in these studies have ranged from 40 days to 6 months. When compared to our previous study in type 2 diabetes,12 in the present study we did not observe any significant improvement in any of the antioxidant parameters after yoga. This could be due to the reason that the antioxidant levels of glutathione, vitamin C and E in prediabetes subjects at baseline may not be deteriorated as in diabetes. The previous study12 was not randomized and also age has a significant role to play in maintaining the antioxidant status of the body.26 All the previous studies in type 2 diabetes comprised of the elderly population. Interventions involving exercise and dietary restriction in prediabetes subjects have shown to improve body weight, blood pressure, fasting glucose and serum insulin significantly.13—15 When compared to the earlier studies on exercise, in this pilot study we found marginal reduction in BMI, waist circumference, fasting glucose and systolic blood pressure.
Possible mechanisms of action Table 2 Baseline characteristics of the subjects in the intervention and control groups. Characteristic Sex (no) Male Female Age (yr) Body-mass index (kg/m2 ) Waist circumference (cm) Fasting plasma glucose (mmol/l) HbA1 c (%) Malondialdehyde (mol/L)
Intervetion group (n = 14)
Control group (n = 15)
6 (43%) 8 (57%) 46.50 ± 13.03 27.2 ± 3.7
8 (53%) 7 (47%) 44.67 ± 9.57 26.2 ± 4.3
88.9 ± 9.9
89.7 ± 13.7
5.3 ± 0.8
5.8 ± 0.9
6.3 ± 0.4 42.2 ± 10.0
6.2 ± 0.3 41.3 ± 5.4
Plus-minus values are mean ± SD.
It has been hypothesized that yoga reduces oxidative stress by two mechanisms.27,28 First mechanism is by reducing the over activation of the hypothalamic—pituitary—adrenal axis and the sympathoadrenalmedullary axis. These systems can produce high levels of stress hormones like cortisol and epinephrine which can increase the heart rate, blood pressure, metabolic and inflammatory responses. Second mechanism is that yoga emphasis on long exhalation and conscious slow breathing which reactivates the parasympathetic nervous system leading to these positive changes.
Limitations and scope for future study As this is a pilot study, the sample size was small with 14 in the experimental and 15 in control group. This may have affected the ability of the findings to be generalized to the broader population. The study results are encouraging and show that yoga might be an effective adjunctive treatment for oxidative stress reduction in subjects with prediabetes.
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes
575
Table 3 Changes in selected clinical and oxidative stress variables from baseline to the end of 3 month follow-up in the intervention and control groups. Variables
Fasting plasma glucose (mmol/l) Post prandial plasma glucose (mmol/l) HbA1 c (%) BMI (kg/m2 ) Waist circumference (cm) Waist-to-hip ratio Systolic blood pressure (mmHg) Diastolic blood pressure (mmHg) Malondialdehyde (mol/L) Glutathione (mol/gmHb) Vitamin C (mol/L) Vitamin E (mol/L) Superoxide dismutase (unit/gmHb)
Intervention group (n = 14)
Control group (n = 15)
Baseline (95% CI)
3 months (95% CI)
Baseline (95% CI)
3 months (95% CI)
5.3 ± 0.8 (5.3—6.2) 7.2 ± 1.1 (6.6—7.8) 6.3 ± 0.4 (6.1—6.6) 27.2 ± 3.7 (25.0—29.3) 88.9 ± 9.9 (84.2—95.6) 0.89 ± 0.04 (0.80—0.90) 125.5 ± 17.9 (115.1—135.9) 86.4 ± 9.2 (81.4—91.7) 42.2 ± 10.0 (36.0—48.0) 7.8 ± 2.5 (6.4—9.3) 27.3 ± 13.6 (19.3—35.2) 57.6 ± 16.0 (48.1—66.9) 4721.0 ± 1263.0 (3992.0—5450)
5.1 ± 0.7 (4.7—5.5) 6.6 ± 1.1 (6.0—7.2) 6.2 ± 0.4 (6.0—6.5) 26.8 ± 3.5 (24.7—28.8) 89.4 ± 9.1 (83.2—93.7) 0.88 ± 0.04 (0.85—0.90) 119.1 ± 13.2 (111.5—126.7) 81.0 ± 5.9 (77.5—84.4) 37.3 ± 6.7 (33.5—41.2) 8.2 ± 2.4 (6.8—10.0) 27.3 ± 14.8 (18.7—35.8) 52.5 ± 14.2 (44.3—60.6) 4340.0 ± 978.0 (3776.0—4905.0)
5.8 ± 0.9 (5.3—6.2) 6.8 ± 1.0 (6.3—7.4) 6.2 ± 0.3 (6.0—6.3) 26.2 ± 4.3 (23.8—28.6) 89.7 ± 13.7 (82.1—97.3) 0.92 ± 0.08 (0.88—0.96) 121.8 ± 9.6 (116.0—127.1) 78.7 ± 8.6 (73.9—83.4) 41.3 ± 5.4 (38.0—44.3) 8.3 ± 3.6 (6.3—10.2) 24.4 ± 9.6 (19.3—30.1) 53.6 ± 16.9 (44.1—62.7) 5056.0 ± 1069.0 (4464.0—5648.0)
5.6 ± 0.7 (5.2—5.9) 6.5 ± 1.4 (5.7—7.2) 6.2 ± 0.4 (6.0—6.4) 26.3 ± 4.4 (23.8—28.7) 90.0 ± 13.7 (82.4—97.6) 0.93 ± 0.08 (0.88—0.97) 125.6 ± 13.4 (118.1—133.0) 81.7 ± 8.8 (76.8—86.5) 42.9 ± 4.2 (40.5—45.3) 8.2 ± 2.4 (6.8—9.5) 22.1 ± 10.2 (16.5—27.8) 46.0 ± 8.8 (41.1—50.8) 5900.0 ± 1031.0 (5329.0—6473.0)
F, p valuea
4.97, 0.035 0.30, 0.585 0.73, 0.40 7.0, 0.013 5.56, 0.026 3.33, 0.08 7.4, 0.01 0.26, 0.61 51.7,
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/ctim
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes: A randomized controlled trial夽 Shreelaxmi V. Hegde a,∗, Prabha Adhikari b, Sowmya Shetty c, Poornima Manjrekar d, Vivian D’Souza d a
Department of Biochemistry, Srinivas Institute of Medical Science and Research Centre, Mangalore, India Department of Medicine, Kasturba Medical College and Hospital, Manipal University, Mangalore, Karnataka, India c Department of Community Medicine, Srinivas Institute of Medical Science and Research Centre, Mangalore, India d Departmentof Biochemistry, Kasturba Medical College and Hospital, Manipal University, Mangalore, Karnataka, India Available online 9 September 2013 b
KEYWORDS Prediabetes; Yoga; Oxidative stress; Antioxidants; Glycated haemoglobin
Summary Objectives: To study the effectiveness of yoga intervention on oxidative stress, glycemic status, blood pressure and anthropometry in prediabetes. Design: Randomized-controlled trial. Participants: Twenty nine prediabetes subjects aged 30—75 years. Setting: Yoga was conducted at 4 different community diabetes clinics in Mangalore, India. Interventions: Participants were randomized to either 3-month yoga or wait-list control groups. Main outcome measures: Malondialdehyde, glutathione, vitamin C, vitamin E, superoxide dismutase, plasma glucose, glycated haemoglobin, BMI, waist circumference, waist-to-hip ratio and blood pressure. Results: Yoga intervention resulted in a significant decline in malondialdehyde (p < 0.001), relative to the control group. In comparison with the control, there was a significant improvement in BMI, waist circumference, systolic blood pressure and fasting glucose levels at follow-up. No significant improvement in glycated haemoglobin, waist-to-hip ratio or any of the antioxidants was observed.
夽
This study was funded by Manipal University. Corresponding author at: Department of Biochemistry, Srinivas Institute of Medical Science and Research Centre, Mukka, Mangalore 574021, Karnataka, India. Tel.: +91 824 2425966; fax: +91 824 2442766; mobile: +91 9986668611. E-mail address: [email protected] (S.V. Hegde). ∗
0965-2299/$ — see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ctim.2013.08.013
572
S.V. Hegde et al. Conclusions: Yoga intervention may be helpful in control of oxidative stress in prediabetes subjects. Yoga can also be beneficial in reduction in BMI, waist circumference, systolic blood pressure and fasting glucose. Effect of yoga on antioxidant parameters was not evident in this study. The findings of this study need to be confirmed in larger trials involving active control groups. © 2013 Elsevier Ltd. All rights reserved.
Introduction The incidence of type 2 diabetes mellitus is increasing worldwide. Type 2 diabetes results from various factors like genetic predisposition, environmental and lifestyle risk factors.1 Lifestyle factors such as physical inactivity and dietary changes are the strongest modifiable risk factors in the prediabetes group which progresses them to the stage of diabetes.2,3 Prediabetes is a collective term for people with impaired glucose tolerance and/or impaired fasting glucose.4 Oxidative stress is a steady-state level of reactive oxygen radicals in a biological system. It may result from overproduction of oxygen radicals and/or decreased efficiency of antioxidant system. Non-enzymatic glycosylation, glucose auto-oxidation and polyol pathways are some of the biochemical pathways associated with hyperglycemia in diabetes mellitus leading to oxidative stress.5 Recent studies reveal that oxidative stress is also one of the pathogenic factor leading to insulin resistance, impaired glucose tolerance and ultimately to type 2 diabetes.6,7 Furthermore, macrovascular disease and its risk factors are often already present in this high risk group of developing type 2 diabetes.8 Hence lifestyle interventions designed to reduce oxidative stress in prediabetes may be useful in preventing their progression to type 2 diabetes. Yoga is found to be one of the effective non pharmacological intervention in reducing oxidative stress in type 2 diabetes.9—12 So far, interventions involving dietary change and increased physical activity to bring about weight loss and delay the onset of diabetes are encouraged in prediabetes subjects.13—15 But exercise therapy is a well-recognized model of OST as it increases the stress parameters.16,17 Two mechanisms have been documented to show increase in oxidative stress parameters after exercise, one by increase in oxygen consumption during exercise leading to disturbance of intracellular pro-oxidant-antioxidant homeostasis.18 Second mechanism is by increase in intracellular free radical generation in xanthine oxidase and electron transport chain.16 With this background in the present study we evaluated the effect of 3 months yoga on OST, antioxidant status, glycemic control, blood pressure and anthropometry in subjects with prediabetes.
Methods Recruitment The study was conducted during 2007 and 2008 at Kasturba Medical College Hospital (KMCH), Mangalore, India. Participants were recruited by conducting camps for detection of diabetes through media advertisements. Approval from the institutional ethical committee was taken prior to the study. All participants gave written informed consent. On
the day of the camp (visit 1) all the participants underwent fasting blood glucose and an oral glucose tolerance test (75 g of anhydrous glucose in 250 ml of water). Impaired fasting glucose was defined as fasting plasma glucose concentrations between 100 and 125 mg/dl (5.6—7.0 mmol/L) after an overnight fast. Impaired glucose tolerance was defined as plasma glucose concentrations between 140 and 200 mg/dl (7.8—11.0 mmol/L) 2 h after the oral glucose tolerance test. A lecture session on-role of diet, exercise and yoga in preventing the incidence of type 2 diabetes in prediabetes was conducted by the researcher. Finally 29 subjects were eligible for the study (Fig. 1). Non-alcoholics and non-smokers between the age of 30 and 75 years were only included for the study. Criteria for exclusion were a diagnosis of diabetes mellitus or any other diseases with elevated oxidative stress like cancer, pulmonary tuberculosis, rheumatoid arthritis, history of osteoporosis and infection. Eligible subjects were called for visit 2 during which they were randomized to the intervention group or the control group by means of a computer-generated randomization list. The study was not blinded.
Interventions Yoga centres were located at KMCH and at 4 community diabetes clinics offering primary care to diabetes patients in Mangalore city. Patients in the intervention group were given the choice to select any one of the yoga centre where they would practice yoga for the next 3-months. Yoga sessions consisted of 75—90 min each day interrupted by a two day weekend break for 3-months. Everyday yoga sessions began with asanas, followed by pranayama and shavasana.19 The list of asanas performed are given in Table 1. Compliance to the yoga classes was defined as attendance for atleast 3 days/week at the yoga centre for 3-months as documented by the yoga instructor. Subjects in the control group were the wait-list control group. Participants of both the groups were telephoned monthly by the researcher to monitor their adherence, improve their enthusiasm and to assist with any problems encountered with the study.
Outcome measures Outcome measures were assessed at baseline (visit 2) and 3-months. All study subjects completed a medical history questionnaire and underwent a physical examination that included anthropometric and blood pressure measurements according to standardized routines. Seven ml of venous blood was collected in EDTA and flouride tubes and immediately centrifuged to separate cells and plasma. Plasma was analysed for glucose, vitamin C and vitamin E. From the packed cells, red blood cell hemolysates were prepared to analyse malondialdehyde, reduced glutathione and superoxide dismutase (SOD) levels.
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes
Figure 1
573
Flow diagram for the trial: yoga intervention vs control.
Malondialdehyde, a product of lipid peroxidation was measured according to Stocks and Dormandy.20 Malondialdehyde reacts with thiobarbituric acid reagent in acidic medium to give pink colour at 97 ◦ C. The absorbance of the coloured product was estimated at 535 nm using a spectrophotometer. Reduced glutathione was determined by the method of Beutler et al.21 which is based upon the development of yellow coloured complex when 5,5 -dithiobis-2-nitrobenzoic acid reacts with sulfhydryl compounds. Activity of SOD was measured by Beauchamp and Fridovich method.22 Inhibition of reduction of nitroblue tetrazolium by superoxide radicals generated during the reaction was used as the basis for the assay of SOD. Vitamin C was estimated by 2,4-dinitro phenyl hydrazine.23 The method followed for estimation of vitamin E was that of Bieri et al.24 Tocopherols and carotenes were first extracted into petroleum ether and the absorbance was read at 460 nm to measure the carotenes. A correction was made for this after adding ferric chloride and read at 520 nm. Plasma glucose was measured by glucose oxidase method and glycated haemoglobin (HbA1 c) by particle enhanced immunoturbidimetric method using Dia Sys diagnostic kits, Holzheim, Germany in Hitachi 917 random access chemistry analyser.
Statistical analysis Analysis of endpoints was based on the principle of intention-to-treat using statistical package for social sciences (SPSS), version 16.0. Statistical analysis was done using ANCOVA taking baseline measurement of all the parameters (0 month) as a covariate and the measurement at 3 month being taken as dependent variable with fixed factor as the group (yoga and control). F value along with the descriptive that is mean, SD and CI were reported. A p-value of less than 0.05 was considered as statistically significant.
Results All 29 subjects completed the study. The study population comprised of impaired fasting glucose (5 no), impaired glucose tolerance (17 no) and impaired fasting glucose plus impaired glucose tolerance (7 no) subjects. No adverse events were observed during the intervention period. Average attendance at the yoga classes was 90%. The mean (±SD) age in yoga group was 46.50 (±13.03) years and 44.67 (±9.57) years in the control group (Table 2). Number of males/females recruited for the study was 6/8 in yoga
574
S.V. Hegde et al.
Table 1 Set of asanas and pranayama included in the yoga intervention. Sanskrit
English
Tadasana Padahastasana Vrikshasana Trikonasana Parshvothanasana
Mountain pose 2 min Forward bend pose 3 min Tree pose 3 min Triangle pose 3 min Extreme sideways 3 min stretch pose Thunderbolt pose 3 min Twist pose 4 min Cow-faced pose 4 min Seated forward 4 min bend pose Raised feet pose 4 min Wind relieving pose 5 min Cobra pose 3 min Locust pose 3 min Bow pose 3 min Inverted action pose 4 min Teeth hissing 8 min Bee breathing 6 min Alternate nostril 10 min breathing Corpse pose 10 min
Vajrasana Vakrasana Gomukasana Paschimotasana Uttanapadasana Pawanamuktasana Bhujangasana Shalabasana Dhanurasana Viparitakarani Sitkari pranayama Bhramari pranayama Anuloma viloma Shavasana
Time duration
intervention and 8/7 in control group. Measurements like BMI, waist circumference, waist-to-hip ratio, blood pressure, fasting plasma glucose, post prandial plasma glucose, HbA1 c, malondialdehyde and antioxidants were comparable at baseline. Yoga intervention in prediabetes significantly reduced BMI, waist circumference, systolic blood pressure and fasting plasma glucose levels (Table 3). There was a significant improvement in malondialdehyde and SOD levels. There was no significant improvement in waist circumference, post prandial plasma glucose, HbA1 c and other antioxidants.
Discussion Principle finding The present study demonstrates that yoga intervention in prediabetes can significantly reduce oxidative stress as evidenced by malondialdehyde and superoxide dismutase levels. In this study the participants in yoga group showed a marginal reduction in other variables like BMI, waist circumference, fasting glucose and systolic blood pressure. Prediabetes is an intermediary stage between normal glucose tolerance and decreased tolerance to glucose as in type 2 diabetes mellitus. Studies reveal that this mild increase in blood glucose in prediabetes can result in oxidative stress.6,25 Thus there is a gradual rise in oxidative stress from the stage of prediabetes to diabetes without complications and with various complications.6 Many of the controlled trials in type 2 diabetes have shown improvement in oxidative stress markers and glycemic control after yoga intervention.9—12 The duration of yoga intervention delivered in these studies have ranged from 40 days to 6 months. When compared to our previous study in type 2 diabetes,12 in the present study we did not observe any significant improvement in any of the antioxidant parameters after yoga. This could be due to the reason that the antioxidant levels of glutathione, vitamin C and E in prediabetes subjects at baseline may not be deteriorated as in diabetes. The previous study12 was not randomized and also age has a significant role to play in maintaining the antioxidant status of the body.26 All the previous studies in type 2 diabetes comprised of the elderly population. Interventions involving exercise and dietary restriction in prediabetes subjects have shown to improve body weight, blood pressure, fasting glucose and serum insulin significantly.13—15 When compared to the earlier studies on exercise, in this pilot study we found marginal reduction in BMI, waist circumference, fasting glucose and systolic blood pressure.
Possible mechanisms of action Table 2 Baseline characteristics of the subjects in the intervention and control groups. Characteristic Sex (no) Male Female Age (yr) Body-mass index (kg/m2 ) Waist circumference (cm) Fasting plasma glucose (mmol/l) HbA1 c (%) Malondialdehyde (mol/L)
Intervetion group (n = 14)
Control group (n = 15)
6 (43%) 8 (57%) 46.50 ± 13.03 27.2 ± 3.7
8 (53%) 7 (47%) 44.67 ± 9.57 26.2 ± 4.3
88.9 ± 9.9
89.7 ± 13.7
5.3 ± 0.8
5.8 ± 0.9
6.3 ± 0.4 42.2 ± 10.0
6.2 ± 0.3 41.3 ± 5.4
Plus-minus values are mean ± SD.
It has been hypothesized that yoga reduces oxidative stress by two mechanisms.27,28 First mechanism is by reducing the over activation of the hypothalamic—pituitary—adrenal axis and the sympathoadrenalmedullary axis. These systems can produce high levels of stress hormones like cortisol and epinephrine which can increase the heart rate, blood pressure, metabolic and inflammatory responses. Second mechanism is that yoga emphasis on long exhalation and conscious slow breathing which reactivates the parasympathetic nervous system leading to these positive changes.
Limitations and scope for future study As this is a pilot study, the sample size was small with 14 in the experimental and 15 in control group. This may have affected the ability of the findings to be generalized to the broader population. The study results are encouraging and show that yoga might be an effective adjunctive treatment for oxidative stress reduction in subjects with prediabetes.
Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes
575
Table 3 Changes in selected clinical and oxidative stress variables from baseline to the end of 3 month follow-up in the intervention and control groups. Variables
Fasting plasma glucose (mmol/l) Post prandial plasma glucose (mmol/l) HbA1 c (%) BMI (kg/m2 ) Waist circumference (cm) Waist-to-hip ratio Systolic blood pressure (mmHg) Diastolic blood pressure (mmHg) Malondialdehyde (mol/L) Glutathione (mol/gmHb) Vitamin C (mol/L) Vitamin E (mol/L) Superoxide dismutase (unit/gmHb)
Intervention group (n = 14)
Control group (n = 15)
Baseline (95% CI)
3 months (95% CI)
Baseline (95% CI)
3 months (95% CI)
5.3 ± 0.8 (5.3—6.2) 7.2 ± 1.1 (6.6—7.8) 6.3 ± 0.4 (6.1—6.6) 27.2 ± 3.7 (25.0—29.3) 88.9 ± 9.9 (84.2—95.6) 0.89 ± 0.04 (0.80—0.90) 125.5 ± 17.9 (115.1—135.9) 86.4 ± 9.2 (81.4—91.7) 42.2 ± 10.0 (36.0—48.0) 7.8 ± 2.5 (6.4—9.3) 27.3 ± 13.6 (19.3—35.2) 57.6 ± 16.0 (48.1—66.9) 4721.0 ± 1263.0 (3992.0—5450)
5.1 ± 0.7 (4.7—5.5) 6.6 ± 1.1 (6.0—7.2) 6.2 ± 0.4 (6.0—6.5) 26.8 ± 3.5 (24.7—28.8) 89.4 ± 9.1 (83.2—93.7) 0.88 ± 0.04 (0.85—0.90) 119.1 ± 13.2 (111.5—126.7) 81.0 ± 5.9 (77.5—84.4) 37.3 ± 6.7 (33.5—41.2) 8.2 ± 2.4 (6.8—10.0) 27.3 ± 14.8 (18.7—35.8) 52.5 ± 14.2 (44.3—60.6) 4340.0 ± 978.0 (3776.0—4905.0)
5.8 ± 0.9 (5.3—6.2) 6.8 ± 1.0 (6.3—7.4) 6.2 ± 0.3 (6.0—6.3) 26.2 ± 4.3 (23.8—28.6) 89.7 ± 13.7 (82.1—97.3) 0.92 ± 0.08 (0.88—0.96) 121.8 ± 9.6 (116.0—127.1) 78.7 ± 8.6 (73.9—83.4) 41.3 ± 5.4 (38.0—44.3) 8.3 ± 3.6 (6.3—10.2) 24.4 ± 9.6 (19.3—30.1) 53.6 ± 16.9 (44.1—62.7) 5056.0 ± 1069.0 (4464.0—5648.0)
5.6 ± 0.7 (5.2—5.9) 6.5 ± 1.4 (5.7—7.2) 6.2 ± 0.4 (6.0—6.4) 26.3 ± 4.4 (23.8—28.7) 90.0 ± 13.7 (82.4—97.6) 0.93 ± 0.08 (0.88—0.97) 125.6 ± 13.4 (118.1—133.0) 81.7 ± 8.8 (76.8—86.5) 42.9 ± 4.2 (40.5—45.3) 8.2 ± 2.4 (6.8—9.5) 22.1 ± 10.2 (16.5—27.8) 46.0 ± 8.8 (41.1—50.8) 5900.0 ± 1031.0 (5329.0—6473.0)
F, p valuea
4.97, 0.035 0.30, 0.585 0.73, 0.40 7.0, 0.013 5.56, 0.026 3.33, 0.08 7.4, 0.01 0.26, 0.61 51.7,
