Dietary intakes and antioxidant status in mind-body exercising pre- and postmenopausal women

Abstract

Objective

The decline in antioxidant defenses due to both estrogen loss and frequent adoption of poor dietary choices exposes postmenopausal women to cardiovascular diseases. Adequate nutrition and physical exercise are two factors of health promotion. This study investigated whether regular practice of mind-body exercise (yoga and/or tai chi) alters dietary intake and antioxidant status and balances the menopause related increases in lipid peroxidation and cardiovascular risk.

Design

Cross-sectional study. Setting: The study was conducted in an urban community in Bangkok (Thailand) between May and August 2007.

Participants

Premenopausal (Pre M; 39±8 yrs; n=56) and postmenopausal (Post M; 54±5 yrs; n=39) women who had been practicing yoga (Y) and/or tai chi (TC) more than 3 hours/week for a year, or who had no regular physical activity practice (sedentary, S).

Measurements

All participants completed food frequency questionnaires and 4-day food and activity records. Blood was collected on day 5. Factorial ANOVA tests were performed according to menopause status, exercise, and hormone replacement therapy (HRT) groups.

Results

Post M had higher (p = 0.01) dietary fiber intake compared with Pre M. Yoga practitioners had lower BMI (p = 0.004) and lower fat intake (p = 0.02) compared with their S and TC counterparts. Plasma total antioxidant status was significantly and independently lower and higher in Y and Post M groups, respectively. However, no difference was shown after adjusting for BMI. Regardless of menopause status and HRT, the activity of erythrocyte glutathione peroxidase an aerobic training responsive enzyme was higher (p < 0.001 ) in TC practitioners compared with other groups. No effects were shown on erythrocyte superoxide dismutase activity, plasma lipid peroxidation (TEARS) or total homocysteine concentrations.

Conclusion

Yoga and tai chi exercises can be used as components of a strategy to promote healthy lifestyles (balanced diet and moderate intensity exercise) in vulnerable populations, such as menopausal women, in order to prevent aging induced oxidative stress diseases.

Introduction

In Thailand, economic, political, and environmental changes and the adoption of western culture have had an impact on the way of life and eating behaviors of the Thai people. This in turn has increased the incidence of psychological stress- and oxidative stress-related diseases, such as cancer, diabetes, and cardiovascular diseases. The consequences of both poor nutrition and physical inactivity are expected to manifest in the near future in postmenopausal women as an increased incidence of these diseases. With menopause, the decline of estrogen, combined with the adoption of poor dietary choices and a sedentary lifestyle, leads to a decrease in women antioxidant defenses.

We have previously shown that aerobic exercise training improves the glutathione system in both sedentary and elderly subjects 1, 2. In addition to these endogenous antioxidant effects, our previous studies showed that exercising improves the quality of dietary intake. Athletes who have high daily energy expenditures have been shown to consume food with high nutrient density regarding vegetal proteins, carbohydrates, vitamin C, folate and selenium, and reach recommended food nutrient intake levels more frequently than non exercising subjects 3, 4, 5. Consequently, the antioxidant response to regular exercise is suggested to be investigated in relation to dietary micronutrient intake (6). Particularly, the concentration of plasma total homocysteine, a cardiovascular risk marker, is lower in the subjects who regularly perform aerobic exercises and this effect could be attributed to their higher folate intake (4).

Paradoxically, elements of the Asian lifestyle, such as “Thai diet” and mind-body exercises, are increasingly popular in western countries for their healthy-enhancing patterns. The “Thai diet” in particular contains a wide variety of vegetables, fruits, herbs, and spices (7) with high antioxidant densities 8, 9, 10. Yoga and tai chi are mind-body exercises. These two physical activities show similar patterns consisting of slow and rotational movements with deep breathing and meditation. Both are suitable for postmenopausal women because of their low impact and low velocity (11). While yoga intensity may be too low to induce cardiovascular effects, tai chi is a moderate intensity physical activity (12) that can promote the significant metabolic strain necessary for subsequent adaptations. Interestingly, the yogic philosophy is that the true benefits of nutrients are found in their natural form and not in their isolate form. Moreover, the basic yogic principle of nutrition is to eat small quantities of high quality food, i.e., a diet rich in fruits, vegetables, whole grains and nuts (13). This diet provides a wide variety of antioxidants and is low in fat. Thus, both yoga and tai chi would be useful components of a strategy to promote a healthy lifestyle (regular physical activity and balanced diet) in vulnerable populations such as in postmenopausal women.

We investigated 1) whether regular practice of yoga and/or tai chi exercise affects dietary intake, antioxidant and lipid status, plasma lipid peroxidation, and total homocysteine levels, and 2) whether these effects depend on the menopause status. We conducted a cross-sectional study in pre- and postmenopausal Thai women who regularly practice yoga and/or tai chi. The confounding effects of hormone replacement therapy (HRT) and calcium and antioxidant supplements on the investigated variables were taken into account.

Materials and methods

Subjects

The study was conducted in an urban community in Bangkok (Thailand) between May and August 2007. One hundred and twenty healthy women between 25 and 65 years old were enrolled in the study and 100 completed the study (characteristics in Table 2). The women were assigned to groups according to their pre- (n=56) and postmenopausal (n=39) status using the Stage of Reproductive Aging Workshop menstrual criteria (14). Five women were in the perimenopausal period and were excluded from this study. Sixty-one women were regular practitioners of mind-body exercise (Y, yoga group, n = 32; TC, tai chi group, n=16; Y+TC, yoga + tai chi group, n=13), whereas 34 women were sedentary (S group) (Table 2).

Table 2.

Daily energy expenditure and daily nutrient intakes of pre- (Pre M) and postmenopausal (Post M) women

	Pre M (n = 56)	Post M (n = 39)	Thai DRI
Age (yrs)	39 ± 8	54 ± 5*
BMI (kg/m2)	22 ± 4	23 ± 4*
Energy expenditure (kcal/d)	1749 ± 399	1892 ± 328
Energy intake (kcal/d)	1651±461	1769 ± 625	1750
Carbohydrates (g/d)	206 ± 60	231 ± 91	196.9-284.4
% Energy intake	50 ± 6	53 ± 9	45-65
Proteins (g/kg BW/d)	1.40 ± 0.48	1.40 ± 0.80	1
% Energy intake	18 ± 4	17 ± 5	10-35
Animal (% total proteins)	68 ± 13	64 ± 16
Vegetal (% total proteins)	32 ± 13	36 ± 16
Lipid (g/d)	59 ± 21	57 ± 23	38.9-68.1
% Energy intake	32 ± 5	29 ± 7*	20-35
Dietary fiber (mg/d)	9.21 ± 3.76	12.58 ± 6.28*	25
Cholesterol (mg/d)	251 ± 130	224 ± 162	ND
Calcium (mg/d)	609 ± 249	591 ± 300	800
% Thai DRI	76 ± 32	62 ± 31*
Ca (+ Ca supplement) (mg/d)	659 ± 316	958 ± 576*
Vitamin A (RE/d)	444 ± 450	386 ± 395	600
% Thai DRI	73 ± 75	64 ± 66
Retinol (^g/d)	337 ± 442	275 ± 380	ND
ß-carotene (^g/d)	966 ± 700	1066 ± 981	ND
Vitamin C (mg/d)	86 ± 79	133 ± 116	75
% Thai DRI	113 ± 100	177 ± 155

Values are expressed as mean ± SD. *p < 0.05 vs Pre M. BMI, Body Mass Index; DRI, Dietary Reference Intake for Thai women; ND, Not Determined.

The participants were recruited through advertisements in Chulalongkorn University media, health education websites, invitation leaflets, and posters displayed in yoga institute networks, tai chi schools, the university campus, public parks, senior clubs and other public places. Women involved in regular yoga and/or tai chi activities for more than a year with a minimum of three training sessions per week, each lasting more than an hour, were selected for the mind-body exercise group. Women with no regular physical exercise for a minimum of one year were selected for the sedentary group. A preliminary lifestyle questionnaire was given to all participants. All eligible volunteers were non-smokers and none had renal or hepatic diseases, diabetes, asthma, cancer, heart disease or hypertension. Participants were informed of the nature and the progression of the experiment before giving their formal consent. Forty-six percent of Post M women had been taking calcium supplements (500-1500 mg/day) for more than 6 months. Fourteen percent of Pre M women and 28% of Post M women had been taking antioxidant supplements (vitamin E: 100-400 IU/day and/or vitamin C: 200-1000 IU/day) for a period of more than 6 months. Eighteen percent of Post M women had been taking HRT for more than 6 months.

The survey protocol was approved by the Ethical Review Committee for Research Involving Human Subjects in Research (Approval No. 076/2006, Chulalongkorn University), in accordance with the International Conference on Harmonization - Good Clinical Practice (ICH-GCP).

Experimental procedures

Participants completed 4-day food and activity records to quantify nutrient intake and daily energy expenditure (EE), respectively. Fasting venous blood samples were collected in resting conditions on day 5.

Dietary and activity records

Each subject completed a 4-day food record and a 4-day activity diary representative of typical training days, in a notebook. Participants were asked to maintain their normal lifestyle (diet and physical activity) during the study. At the start, a standardized individual information session gave each subject instructions on how to record their daily food intake. In parallel, participants completed a food frequency questionnaire (FFQ). Food quantities were estimated using standard measures for a cup, tablespoon and teaspoon (validated by the Institute of Nutrition, Mahidol University) and specifying the number of units/code corresponding to the size of the food portion by comparison with photos from an adapted portion book (15).

The activities to be recorded in the 4-day activity diary were divided into the following groups: (1) sleep position; (2) mild activities (sitting, rest: TV, computer, video games, reading, meals, working in office, lecture, etc.); (3) moderate activities (standing position: walking, toilet, housework, working in laboratory, shopping, etc.); (4) slightly high activities (quick walking, active leisure, gardening, etc.); (5) yoga training; (6) tai chi training. The total duration was reported for each activity group.

After the 4 days of record-keeping, the diet and activity records were reviewed individually by an expert to ensure completeness. The average nutritional intakes were calculated using INMUCAL nutrient software, version 2007, which uses the Thai dietary database of the Institute of Nutrition, Mahidol University, and the Nutrition Division, Department of Health, Ministry of Public Health of Thailand (version 2003).

The estimated dietary intakes were compared with the Thai Dietary Recommendation of Intakes (Thai DRI) established by the Department of Health, Ministry of Public Health of Thailand, 2003. The estimated energy expenditure was calculated using an adapted method of the Ainsworth Compendium (16). The energy cost of physical activities was expressed as metabolic equivalents.

Blood sampling

Blood samples were obtained on day 5 after the 4 days of diet and activities recording. Fasting blood samples were drawn from a forearm vein and collected in K3EDTA tubes and Li heparin tubes (Vacuette, Greiner Bio-One, Germany) in the morning. Blood collection was avoided during the menstruation period. Hematological parameters were analyzed from EDTA tubes within 4 hours of blood collection under strict quality control conditions. Heparinized plasma was removed within an hour of blood collection for total antioxidant status, the lipid peroxidation marker, and total homocysteine analyses. Packed red blood cells were washed three times with two volumes of isotonic saline solution. The washed RBCs were hemolyzed by suspension in double distilled water, centrifuged at 3000 x g at 4°C for 15 min, and then kept at -80°C until endogenous antioxidant enzyme analysis. The samples were stored in cryotubes at -80°C and thawed only once before analysis to eliminate a freeze-thaw effect.

All assays for each marker were performed with the same conditions (same set of reagent kit, same control, same automate) on the same day, to avoid inter-assay variations. The automate system was set to randomly repeat the control during the batch to avoid run-to-run variations. The within-run coefficient of variation was less than 2.5 % for the biochemical markers measured.

Routine haematological and biochemical measurements Hemoglobin concentration, hematocrit, and leukocyte and platelet counts were analyzed with a Sysmex SF-3000 hematoanalyzer (TOA Company, Japan). Uric acid, triglycerides, and HDL-, LDL- and total-cholesterols were analyzed from heparinized plasma by RANDOX reagent kits using a biochemical analyzer (Vitalab Selectra XL, Flexor Company, the Netherlands).

Total antioxidant status (TAS)

Total antioxidant activity was analyzed by radical cation decolorization assay (17). This assay is based on the inhibition by antioxidants of the free radical cation from ABTS (2,2’-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid diamonium salt) using spectrophotometer (Shidmadzu UV-1601, Japan) measurement at 734 nm. This assay was calibrated using Trolox as the standard.

Lipid peroxidation marker (TBARS)

Lipid peroxidation was assayed by measuring the formation of malondialdehyde (18), using thiobarbituric acid (TBA) and trichloroacetic acid (TCA), and was then measured using a UV spectrophotometer (Shidmadzu UV-1601, Japan) calibrated by tetra-ethoxypropane as the standard.

Erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities

Erythrocyte SOD and GPx activities were measured by enzyme kinetic-colorimetric assay (Randox Laboratories, UK).

Total plasma homocysteine (tHcy)

Total homocysteine was analyzed by a fluorescence polarization immunoas say (FPIA) for the quantitative measurement of total L-homocysteine in plasma using the AxSYM automatic system (Abbott Laboratories, USA).

Statistical Analysis

Differences between groups (menopause; mind-body exercise) were analyzed by a two-way analysis of variance (ANOVA) followed by a post-hoc test (Fischer PLSD). As groups were not homogeneous regarding age, HRT or supplement used (calcium, antioxidant), effects inherent to these factors were first tested by a one-way ANOVA. Statistical significance was accepted at p < 0.05. All values are presented as mean ± standard deviation. SPSS, version 15.0, was used for all analyses (SPSS, Inc., USA).

Results

Dietary intakes

Menopause effects

Rice and side dishes were the main staples consumed. Green/red curry with chicken/pork was the most frequently consumed meal of Pre M women while soup with vegetable and/or pork/chicken was the most consumed by Post M women. Guava was the most frequent fruit consumed by both Pre M and Post M women (Table 1). Energy intake, as well as the percentage of energy intake derived from carbohydrates, proteins and lipids, were within the ranges of Thai DRI in both groups (Table 2). Calcium intake (without supplement intake) were below Thai DRI in both groups (Table 2). Fifty-nine percent of Pre M and 74 % of Post M women reached 2/3 of

Table 1.

Most frequent food intakes in pre- (Pre M) and postmenopausal (Post M) women according to mind-body exercise groups

	% Pre M consumer				% Post M consumer
	S	Y	TC	Y+TC	Total	S	Y	TC	Y+TC	Total
	(n=21)	(n=23)	(n=6)	(n=6)	(n=56)	(n=13)	(n=9)	(n=10)	(n=7)	(n=39)
One plate dish
Rice noodleds with meat/fish products	53	39	16	50	43	54	33	70	42	51
Wheat Chinese noodles with pork/chicken	5	17	33	33	16	7	11	40	14	18
Vegetable salad western style	5	22	66	50	23	15	55	50	57	41
Staple rice
Steamed rice, polished	100	91	100	100	96	92	89	100	86	92
Steamd rice, whole grain, partial polished	4	30	16	33	20	15	33	50	14	28
Side dish foods
Green/red curry with chicken/pork	62(1)	17	50(1)	16	38(1)	38(3)	11	20	42(2)	28(2)
Chicken/pork fried with holy basil leaves	293	26	16	16	25	30	22	20	14	23
Soup with vegetable and/or pork/chicken	43(2)	52(1)	16	16	34(2)	54(1)	66(1)	40(1)	42(2)	51(1)
Spicy Thai style soup (Kaeng Som)	14	13	16	16	14	46(2)	11	20	14	26
Spicy papaya salad Thai style (Som Tam)	24	40(3)	0	16	27	1	22	0	14	10
Mixed-vegetable fried	14	52(1)	16	50(1)	34(2)	30	22	10	57(1)	28(2)
Fruits
Guava	29	23	33	33	27(1)	38	44	40	29	38(1)
Orange	43	4	33	0	21	23	22	30	14	23
Apple	0	22	33	33	16	8	33	40	42	26
Rambutan	43	23	0	33	25	23	11	40	14	23
Mango	24	22	16	33	23	23	22	10	14	18

(1) Most frequent food ranking (from 4-day dietary record). S, Sedentary; Y, Yoga; TC, Tai Chi; Y+C, Yoga and Tai Chi

Thai DRI for vitamin C (Table 2).

The percentage of energy intake derived from lipids, and fiber intake were respectively lower (p = 0.026) and higher (p = 0.013) in Post M compared with Pre M women (Table 2). No significant difference between groups was evident for daily energy expenditure and for daily dietary energy, calcium, retinol, vitamin C, and ß-carotene intakes (Table 2).

Mind-body exercise effects

Independently of their menopause status, Y practitioners had a lower BMI (p = 0.004) and lower daily lipid intake (p = 0.022) compared with other groups (Table 3). Daily energy expenditure and daily dietary intakes of proteins, carbohydrates, calcium, retinol, vitamin C, and ß-carotene were not significantly different between groups (Table 3).

Table 3.

Selected characteristics and dietary intakes in pre- (Pre M) and postmenopausal (Post M) women according to mind-body exercise groups

	Pre M S (n=21)	Y (n=23)	TC (n=6)	Y+TC (n=6)	Post M S (n=13)	Y (n=9)	TC (n=10)	Y+TC (n=7)
Age (yrs)	40 ± 9	35 ± 6	47 ± 4	41 ± 7	56 ± 5	53 ± 3	54 ± 5	52 ± 5
Weight (kg)	56 ± 9	53 ± 12	53 ± 7	50 ± 4	54 ± 8	57 ± 12	54 ± 6	58 ± 15
BMI (kg/m2)	22.6 ± 3.1*	19.9 ± 1.4	21.5 ± 3.3*	20.5 ± 1.7	23.0 ± 3.2*	21.2 ± 1.8	21.7 ± 2.3*	22.0 ± 2.6
EE (kcal/d)	1755 ± 294	1675 ± 527	1915±282	1779 ± 194	1713 ± 318	1967±319	1912 ± 214	2100 ± 385
EI (kcal/d)	1776 ± 577	1550 ± 329	1563 ± 398	1688 ± 503	1692 ± 506	1324 ± 367	2145 ± 835	1753 ± 434
Carbohydrates (g/d)	221 ± 68	193 ± 53	188 ± 46	225 ± 59	231 ± 86	186 ± 73	279 ± 105	219 ± 84
% EI	51 ± 7	49 ± 6	48 ± 4	54 ± 7	55 ± 9	55 ± 11	53 ± 9	49 ± 7
Proteins (g/kg BW/d)	1.49 ± 0.53	1.42 ± 0.51	1.16 ± 0.26	1.23 ± 0.23	1.34 ± 0.45	1.03 ± 0.35	1.80 ± 1.38	1.42 ± 0.32
% EI	19 ± 3	19 ± 5	16 ± 2	15 ± 2	17 ± 2	18 ± 6	17 ± 7	19 ± 4
Animal (%total Prot)	73 ± 10	69 ± 14	59 ± 16	61 ± 10	60 ± 20	66 ± 17	63 ± 14	68 ± 13
Vegetal (%total Prot)	27 ± 10	31 ± 14	41 ± 16	39 ± 10	40 ± 20	34 ± 17	37 ± 14	32 ± 13
Lipid (g/d)	61 ± 26*	55 ± 13	63 ± 18*	61 ± 30*	54 ± 23*	39 ± 15	72 ± 28*	61 ± 10*
% EI	31 ± 6	32 ± 4	36 ± 4	32 ± 8	29 ± 8	27 ± 8	30 ± 4	32 ± 5
Dietary fiber (mg/d)	9.48 ± 3.23	8.68 ± 4.11	8.58 ± 4.24	10.96 ± 4.00	14.33 ± 7.48	9.57 ± 4.66	13.50 ± 5.19	11.87 ± 6.79
Cholesterol (mg/d)	275 ± 140	256 ± 138	199 ± 58	198 ± 105	206 ± 108	177 ± 66	285 ± 288	230 ± 41
Calcium (mg/d)	656 ± 249	604 ± 267	445 ± 143	624 ± 245	526 ± 257	516 ± 190	744 ± 435	589 ± 224
Vitamin A (RE/d)	480 ± 403	499 ± 572	266 ± 166	283 ± 143	370 ± 385	222 ± 132	661 ± 541	233 ± 190
Retinol (^g/d)	386 ± 396	383 ± 561	141 ± 172	180 ± 112	288 ± 383	104 ± 97	528 ± 531	107 ± 49
ß-carotene (^g/d)	845 ± 640	1010 ± 689	1035 ± 645	1151±1065	818±481	1252±1162	1102 ± 811	1234±1621
Vitamin C (mg/d)	84 ± 74	73 ± 69	87 ± 69	145 ± 127	130 ± 108	163 ±134	124 ± 115	114±128

Values are expressed as mean ± SD. *p < 0.05 vs Y. S, Sedentary; Y, yoga; TC, Tai Chi; Y+C, Yoga and Tai Chi; BMI, Body Mass Index; EE, Energy Expenditure; EI, Energy Intake; BW, body weight; RE, Retinol Equivalent.

Biological parameters

Supplement intake effects

In Post M women, HRT users had a higher (p = 0.014) erythrocyte GPx activity than non-users but other evaluated biological parameters were not different (Table 4).

Table 4.

Antioxidant status and oxidative damages markers in postmenopausal women according to calcium, hormone replacement therapy and antioxidant supplement consumptions

	TAS (mmol/l TE)	eSOD (U/g Hb)	eGPx (U/g Hb)	TBARS (/µmol/l)	tHcy (/µmol/l)
Calcium supplement
Non-users, Post M (n = 21)	1.22 ± 0.16	2203 ± 544	46 ± 11	1.72 ± 1.97	11.8 ± 1.8
Users, Post M (n = 18; 46% in S, 45% in Y,	1.16 ± 0.14	2077 ± 438	43 ± 11	0.98 ± 1.62	11.0 ± 2.3
50% in TC, 43% in Y+TC)
Hormone replacement therapy
Non-users, Post M (n = 32)	1.17 ± 0.14	2174 ± 495	42.3 ± 10.7	1.16 ± 1.72	11.3 ± 2.0
Users, Post M (n = 7; 15% in S, 22% in Y,	1.29 ± 0.19	2008 ± 509	53.3 ± 6.3*	2.21 ± 2.10	12.1 ± 2.4
20% in TC, 14% in Y+TC)
Antioxidant supplement
Non-users, Pre M (n = 48)	1.12 ± 0.13	2355 ± 523	42 ± 13	0.76 ± 1.17	11.0 ± 2.5
Non-users, Post M (n = 28)	1.19 ± 0.16	2239 ± 470	44 ± 11	1.30 ± 1.70	11.6 ± 2.3
Users, Pre M (n = 8; 17% in Y, 33% in TC,	1.03 ± 0.14	2295 ± 397	53 ± 14	1.92 ± 2.31	9.3 ± 2.4
33% in Y+TC)
Users, Post M (n = 11; 30% in S, 22% in	1.21 ± 0.15	1903 ± 498	44 ± 12	1.51 ± 2.15	11.1 ± 1.3
Y, 30% in TC, 29% in Y+TC)

Values are expressed as mean ± SD; *p < 0.05 vs non-users. TAS, Total Antioxidant Status; TBARS, plasma Thiobarbituric Acid Reactive Substances; eSOD, erythrocyte Superoxide Dismutase activity; eGPx, erythrocyte Glutathione Peroxidase activity; tHcy, plasma total Homocysteine.

No effect of either antioxidant supplement or calcium supplement used was evidenced on the parameters measured (Table 4).

Menopause effects

Triglycerides (p = 0.003), LDL- (p = 0.006) and total-cholesterol (p = 0.002) concentrations were higher in Post M compared with Pre M women (Table 5).

Table 5.

Hematological and biochemical parameters of pre- (Pre M) and postmenopausal (Post M) women according to mind-body exercise groups

	Pre M					Post M
	S	Y	TC	Y+TC	Total	S	Y	TC	Y+TC	Total
	(n=21)	(n=23)	(n=6)	(n=6)	(n=56)	(n=13)	(n=9)	(n=10)	(n=7)	(n=39)
Hemoglobin (g/dl)	12.8 ± 1.0	12.5 ± 1.0	12.6 ± 1.4	12.5 ± 0.7	12.6 ± 1.0	12.4 ± 1.0	13.2 ± 0.7	12.8 ± 1.6	13.2 ± 1.2	12.8 ± 1.1
Hematocrit (g%)	39 ± 3	38 ± 3	38 ± 3	38 ± 2	38 ± 3	38 ± 2	39 ± 2	39 ± 4	39 ± 3	39 ± 3
Leukocytes (x109/l)	6.21 ± 0.92	5.74 ± 1.55	6.32 ±;1.38	5.35 ±1.40	5.94 ± 1.31	5.41 ±1.18	4.57 ± 0.85	5.21 ± 1.06	4.67 ± 1.22	5.03 ± 1.11*
Platelets (x109/l)	251 ± 38	232 ± 46	246 ± 55	249 ± 51	242 ± 45	204 ± 58	235 ± 63	226 ± 34	234 ± 47	222 ± 52
Glucose (mg/dl)	80 ± 11	78 ± 8	84 ± 31	71 ± 7	79 ± 13	79 ± 10	78 ± 8	83 ±16	80 ± 9	80 ± 11
Uric acid (mg/dl)	4.96 ± 1.67	4.47 ± 0.97	5.02 ± 1.18	4.18 ± 0.38	4.68 ± 1.27	4.98 ± 1.11	5.16 ± 1.59	5.01 ± 0.70	4.83 ± 1.63	5.00 ± 1.21
Triglycerides (mg/dl)	78 ± 31	59 ± 30	74 ± 25	51 ± 11	67 ± 30	86 ± 37	86 ± 27	101 ± 58	92 ± 56	91 ± 43*
Total cholesterol (mg/dl)	199 ± 38	200 ± 42	175 ± 25	196 ± 56	197 ± 40	228 ± 35	223 ± 38	214 ± 37	230 ± 45	223 ± 37*
HDL cholesterol (mg/dl)	54 ± 15	58 ± 9	58 ± 12	67 ± 11	57 ± 12	61 ± 12	58 ± 14	51 ± 10	61 ± 20	58 ± 14
LDL cholesterol (mg/dl)	130 ± 38	130 ± 38	102 ± 18	118 ± 47	126 ± 38	150 ± 34	147 ± 38	143 ± 36	150 ± 35	147 ± 34*
TAS (mmol/l TE)	1.17 ± 0.14	1.04 ± 0.11	1.10 ± 0.08	1.10 ± 0.16	1.10 ± 0.14	1.23 ± 0.12	1.13 ± 0.08	1.22 ±0.21	1.17 ± 0.19	1.20 ± 0.15
eSOD (U/g Hb)	2392 ± 587	2245 ± 512	2426 ± 324	2498 ± 268	2347 ± 504	2067 ± 541	2028 ± 238	2330 ± 465	2173 ± 482	2145 ± 495
TBARS (µmol/l)	0.60 ± 0.46	1.07 ± 1.35	1.73 ± 1.91	1.79 ± 2.48	1.35 ± 1.42	1.33 ± 1.89	0.83 ± 1.78	2.51 ± 1.94	2.19 ± 1.50	1.48 ±1.82
tHcy (µmol/l)	11.1 ± 1.9	10.1 ± 3.2	11.4 ± 2.7	11.1 ± 1.4	10.7 ± 2.6	11.8 ± 1.9	12.0 ± 2.8	10.7 ± 1.3	11.0 ± 2	11.4 ± 2.1

Values are expressed as mean ± SD; *p < 0.05 vs Pre M (Total). S, Sedentary; Y, yoga; TC, Tai Chi; Y+C, Yoga and Tai Chi; TAS, plasma Total Antioxidant Status; TBARS, plasma Thiobarbituric Acid Reactive Substances; eSOD, erythrocyte Superoxide Dismutase activity; tHcy, plasma total Homocysteine.

Total antioxidant status was significantly higher in Post M than in Pre M women but this difference was no longer significant when BMI was taken into account as a covariate in ANOVA analysis. Erythrocyte GPx and SOD activities, plasma TBARS and tHcy concentrations were not significantly different in Pre M compared with Post M women (Table 5).

Mind-body exercise effects

Mind-body exercise and type of mind-body exercise (Y and/or TC) had no significant effect on the routine parameters measured (hemoglobin, hematocrit, leukocytes, platelets, plasma glucose, uric acid, triglycerides, HDL-, LDL- and total-cholesterol concentrations) (Table 5). Plasma TAS was significantly lower in Y group than in the other groups and this effect was independent of the menopause status (Table 5). However, this effect on TAS was also no longer significant when BMI was taken into account as a covariate. Erythrocyte GPx activity was higher (p < 0.001) in TC practitioners and Y+TC practitioners compared with Y and S groups (Figure 1). After exclusion of postmenopausal women who were undergoing HRT, erythrocyte GPx activity was still significantly higher in TC practitioners. No difference among groups was shown on erythrocyte SOD activity, plasma TBARS or tHcy concentrations (Table 5).

Figure 1.

Erythrocyte glutathione peroxidase activity (GPx; Unit/g Hb) in pre- (Pre M) and postmenopausal (Post M) women.

No interaction effect between menopause status and mind-body exercise was shown on any of the investigated parameters.

Discussion

We investigated whether regular practice of yoga and/or tai chi by Thai women affects dietary intake, antioxidant and lipid status, plasma lipid peroxidation, and total homocysteine level, and whether any observed effects would differ according to menopause status.

Although the energy intakes of these women were lower than those of women of the same age living in Europe (19) or of Thai women living in Germany (20), the intakes of the Thai postmenopausal women in our study were higher than those of Bangkok-community women in 1995 and 1999, as reported by Pongpaew et al. (2000) (1,189 kcal/d in 1995 and 1,397 kcal/d in 1999 vs. 1,769 kcal/d in our study). This suggests that the socioeconomic changes in Thailand, as well as place of living, have altered dietary behavior, leading to an increase in energy intakes.

With regard to nutrient intake and mind-body practice of the Thai women in our study, antioxidant intake was not different between groups. Unfortunately, as Thai food composition databases are still incomplete for the content of some micronutrients such as folate and vitamin E, among the antioxidant intakes, only vitamin C and ß-carotene could be considered. Yoga practitioners were shown to have different dietary habits than sedentary women. In fact, vegetable soup, spicy papaya salad, and fried mixed vegetables were the most frequently consumed meals by yoga practitioners, whereas coconut milk, high in saturated fat, is a component of green/red curry, a meal highly consumed in our sedentary and tai chi groups. Fat intake was shown to be significantly lower in yoga practitioners who also tended to have lower energy intakes compared to other groups. Moreover, they have been shown to have a lower BMI. It is possible that the characteristics of the yoga practice itself could have an impact on practitioners’ dietary intakes. Yoga is a holistic mind-body exercise that includes physical exercise, such as “asana” or postures, “pranayama” or breath control, and “vipassana” or meditation (13). Many yoga postures, particularly those that require gentle twisting and strength for body-locked positions, might influence yoga practitioners to reduce energy intake to maintain slimness for proper practice.

With regard to dietary intake, we did not evidence any interaction effect between the practice of mind-body exercise and the menopause status. Indeed, independently of their practice, Post M women had higher fiber intake and lower percentage of lipids in their daily energy intake compared to their sedentary counterparts. They more frequently consumed vegetable soups. However, dietary fiber intake (10.6 g/d) remained below the Thai DRI (25 g/d) in both groups, as it was previously reported in Thai women (20). The Thai diet contains a wide variety of vegetables and herbs, which are thought to provide high fiber intake. However, as these foods are eaten in small quantities and many herbs are grinded and mixed, like in curry paste, fiber intake can actually be lower than expected. This deficit as regard to Thai DRI may also be explained by the low fiber content in rice, the main meal of Thais.

Despite the fact that Post M women, in our study, were more concerned about healthy diet than younger women, they had higher triglycerides and total- and LDL-cholesterol levels than the Pre M women. BMI and TAS were also higher in Post M women than in their Pre M counterparts. Both parameters were significantly lower in the yoga practitioners than in the other groups. As a result of increasing adipocyte sizes, abundant hydrophobic antioxidants such as carotenoids and tocopherol, which are stored in adipocytes (21), can be mobilized to peripheral blood. We therefore took BMI into account as a covariate in the analysis of TAS variations. After adjusting with BMI, the difference shown on TAS according to menopause status and type of mind-body practice was no longer significant. Our results agree with those of Pansini et al. (2008), who evidenced an increase in TAS after menopause and a high correlation between trunk fat mass and total antioxidant status in Post M women (22). As Post M women are unable to optimally control lipid metabolism (23), our results suggest that TAS should be carefully considered in relation to confounding factors such as body fat.

Antioxidant and food supplements are now widely used in Thailand to prevent age-related pathology. Supplement use by Post M women depended mostly on individual preferences. In our study, supplement consumption has no effect on plasma TAS concentrations. Due to the low consumption of milk and dairy products by Thai people (24), calcium intake was shown to be under Thai DRI in both Pre M and Post M groups. Thus, calcium supplement intake allows to complete dietary calcium intake in the Post M calcium supplement users in our study. In agreement with the report of Hahn et al. (2008), we evidenced no effect of calcium supplementation on our antioxidant and damage markers.

As regard to endogenous antioxidants and damage markers variations according to mind-body exercise and menopause groups, we found that erythrocyte GPx activity was significantly higher in TC practitioners (TC and Y+TC groups) compared with S and Y groups, and that this increase was not due to an effect of menopause status or aging. However, erythrocyte SOD activity, plasma TBARS, and tHcy levels were not different. In agreement with the study of Bednarek-Tupikowska (25), we observed that erythrocyte GPx activity in participants who were undergoing hormone replacement therapy was also higher when compared with that of non-therapy users, suggesting that estradiol could benefit the endogenous antioxidant potential in postmenopausal women. We analyzed HRT effects by taking into account this confounding factor in the analysis of the effect of mind-body exercise on antioxidant markers. Erythrocyte GPx activity was still significantly higher in tai chi practitioners. We also excluded all participants who were undergoing HRT in all groups. The difference was still found to be due to the effect of tai chi practice. Hence, the data strongly suggested that tai chi practice improves erythrocyte GPx activity. Tai chi is a style of slow, rotational and multi-segmental exercise that includes deep breathing, meditation, balance and stability (26). It is a weight-bearing exercise that strengthens muscle and is characterized as an aerobic exercise of moderate intensity (12). Glutathione peroxydase is an important antioxidant, protecting against oxidative stress. A decrease in erythrocyte GPx activity was associated with an increased risk of cardiovascular diseases (27). Our previous reports have shown that aerobic training could improve erythrocyte GPx activity in sedentary or elderly subjects 1, 2, 28. Although exposure to moderate oxidative stress can increase GPx mRNA transcription and increase GPx activity (29), aerobic exercise may also reinforce GPx activity by post-translational effects, as previously suggested (1). Regarding the tai chi concept, Chi—”air” in Chinese, or energy flow from breathing—is controlled by an interaction between the mind and the rhythm of body movement, and this condition stimulates meditation during physical movement. A previous study demonstrated that tai chi training could increase plasma nitric oxide metabolite levels (30). Cutaneous microcirculatory function is higher during practice in tai chi practitioners than in their sedentary counterparts, and this may be mediated by enhanced nitric oxide release (30), a potent vaso-relaxant that can also induce the synthesis of the antioxidant glutathione via an increase in the expression of the catalytic subunit of glutamate cysteine ligase (31). Moreover, it has also been shown that the rhythm of breathing, slow and deep, is associated with a significant increase in the gene expression of glutathione S-transferase (32). A plausible explanation is that both a release of nitric oxide and the slow and deep rhythmic breathing during tai chi improve GPx activity in tai chi practitioners and consequently reinforce endogenous antioxidant potential.

Shortcoming inherent to the study is a general limitation of cross-sectional studies. Therefore, further studies with longer intervention periods, larger sample sized are suggested to confirm the presented results. Moreover, interventional studies such as involving mind-body exercise training should be conducted to confirm the effect of the specificity of these physical activities on body antioxidant capacity.

Conclusion

Our study indicated that, in postmenopausal women, the interpretation of antioxidant markers should be made in relation to body fat mass and HRT use. Besides the low-velocity, low-impact and safety benefits, regular practice of tai chi improves endogenous antioxidant defenses in erythrocytes by increasing the activity of the aerobic-responsive enzyme, erythrocyte glutathione peroxidase, in both pre- and postmenopausal women. This effect was not shown in yoga practitioners. We showed that yoga practice is associated with specific dietary behavior, as indicated by the lower fat intake and high vegetable diet. Thus, we conclude that yoga and tai chi exercises can be used as components of a strategy to promote healthy lifestyles in vulnerable populations, such as menopausal women, in order to prevent oxidative stress-related diseases.