Association between empirically derived dietary patterns with blood lipids, fasting blood glucose and blood pressure in adults - the India migration study.

BACKGROUND: Dietary patterns (DPs) in India are heterogenous. To date, data on association of indigenous DPs in India with risk factors of nutrition-related noncommunicable diseases (cardiovascular disease and diabetes), leading causes of premature death and disability, are limited. We aimed to evaluate the associations of empirically-derived DPs with blood lipids, fasting glucose and blood pressure levels in an adult Indian population recruited across four geographical regions of India. METHODS: We used cross-sectional data from the Indian Migration Study (2005-2007). Study participants included urban migrants, their rural siblings and urban residents and their urban siblings from Lucknow, Nagpur, Hyderabad and Bangalore (n = 7067, mean age 40.8 yrs). Information on diet (validated interviewer-administered, 184-item semi-quantitative food frequency questionnaire), tobacco consumption, alcohol intake, physical activity, medical history, as well as anthropometric measurements were collected. Fasting-blood samples were collected for estimation of blood lipids and glucose. Principal component analysis (PCA) was used to identify major DPs based on eigenvalue> 1 and component interpretability. Robust standard error multivariable linear regression models were used to investigate the association of DPs (tertiles) with total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), triglycerides, fasting-blood glucose (FBG), systolic and diastolic blood pressure (SBP and DBP) levels. RESULTS: Three major DPs were identified: 'cereal-savoury' (cooked grains, rice/rice-based dishes, snacks, condiments, soups, nuts), 'fruit-vegetable-sweets-snacks' (Western cereals, vegetables, fruit, fruit juices, cooked milk products, snacks, sugars, sweets) and 'animal food' (red meat, poultry, fish/seafood, eggs) patterns. High intake of the 'animal food' pattern was positively associated with levels of TC (ß = 0.10 mmol/L; 95% CI: 0.02, 0.17 mmol/L; p-trend = 0.013); LDL-C (ß = 0.07 mmol/L; 95% CI: 0.004, 0.14 mmol/L; p-trend = 0.041); HDL-C (ß = 0.02 mmol/L; 95% CI: 0.004, 0.04 mmol/L; p-trend = 0.016), FBG: (ß = 0.09 mmol/L; 95% CI: 0.01, 0.16 mmol/L; p-trend = 0.021) SBP (ß = 1.2 mm/Hg; 95% CI: 0.1, 2.3 mm/Hg; p-trend = 0.032); DBP: (ß = 0.9 mm/Hg; 95% CI: 0.2, 1.5 mm/Hg; p-trend = 0.013). The 'cereal-savoury' and 'fruit-vegetable-sweets-snacks' patterns showed no association with any parameter except for a positive association with diastolic blood pressure for high intake of 'fruits-vegetables-sweets-snacks' pattern. CONCLUSION: Our results indicate positive associations of the 'animal food' pattern with cardio-metabolic risk factors in India. Further longitudinal assessments of dietary patterns in India are required to validate the findings.

Associations between active travel to work and overweight, hypertension, and diabetes in India: a cross-sectional study.

BACKGROUND: Increasing active travel (walking, bicycling, and public transport) is promoted as a key strategy to increase physical activity and reduce the growing burden of noncommunicable diseases (NCDs) globally. Little is known about patterns of active travel or associated cardiovascular health benefits in low- and middle-income countries. This study examines mode and duration of travel to work in rural and urban India and associations between active travel and overweight, hypertension, and diabetes. METHODS AND FINDINGS: Cross-sectional study of 3,902 participants (1,366 rural, 2,536 urban) in the Indian Migration Study. Associations between mode and duration of active travel and cardiovascular risk factors were assessed using random-effect logistic regression models adjusting for age, sex, caste, standard of living, occupation, factory location, leisure time physical activity, daily fat intake, smoking status, and alcohol use. Rural dwellers were significantly more likely to bicycle (68.3% versus 15.9%; p<0.001) to work than urban dwellers. The prevalence of overweight or obesity was 50.0%, 37.6%, 24.2%, 24.9%; hypertension was 17.7%, 11.8%, 6.5%, 9.8%; and diabetes was 10.8%, 7.4%, 3.8%, 7.3% in participants who travelled to work by private transport, public transport, bicycling, and walking, respectively. In the adjusted analysis, those walking (adjusted risk ratio [ARR] 0.72; 95% CI 0.58-0.88) or bicycling to work (ARR 0.66; 95% CI 0.55-0.77) were significantly less likely to be overweight or obese than those travelling by private transport. Those bicycling to work were significantly less likely to have hypertension (ARR 0.51; 95% CI 0.36-0.71) or diabetes (ARR 0.65; 95% CI 0.44-0.95). There was evidence of a dose-response relationship between duration of bicycling to work and being overweight, having hypertension or diabetes. The main limitation of the study is the cross-sectional design, which limits causal inference for the associations found. CONCLUSIONS: Walking and bicycling to work was associated with reduced cardiovascular risk in the Indian population. Efforts to increase active travel in urban areas and halt declines in rural areas should be integral to strategies to maintain healthy weight and prevent NCDs in India. Please see later in the article for the Editors' Summary.

Reproducibility and validity of a quantitative food frequency questionnaire in an urban and rural area of northern India.

Background. Food frequency questionnaires (FFQs) have been used in epidemiological studies across the world to capture the usual food intake of individuals. As food habits vary in different population groups, FFQs should be validated before use. Hence, we determined the reproducibility and validity of FFQs designed for urban and rural populations of northern India. Methods. Separate FFQs, designed for urban and rural populations using standard methods, were administered to a sample of 200 subjects (100 urban and 100 rural) in the age group of 35-70 years in the beginning (baseline FFQ) of the study and after an interval of 1 year (1-year FFQ) to assess their reproducibility. Six 24-hour dietary-recalls, taken at an interval of 2 months over a period of 1 year, were used as a reference method to test the validity. Crude and energy- adjusted nutrient intakes estimated from FFQs and 24-hour dietary-recalls were compared using Pearson correlation coefficients. Bland and Altman plots were also used to test the agreement between the two methods. Results. Nutrient intakes were found to be similar at the baseline and 1-year FFQs in urban and rural areas. The unadjusted Pearson correlation between 24-hour dietary- recalls and 1-year FFQ ranged from 0.22 for vitamin C to 0.63 for iron in the urban area. It ranged from 0.06 for vitamin C to 0.74 for energy in the rural area. The correlations lowered after adjusting for energy and there was a minimal increase after de-attenuation. Conclusion. The FFQs were reproducible and valid for assessing nutrient intakes except for some micronutrients.

Evaluation of the Indian Migration Study Physical Activity Questionnaire (IMS-PAQ): a cross-sectional study.

BACKGROUND: Socio-cultural differences for country-specific activities are rarely addressed in physical activity questionnaires. We examined the reliability and validity of the Indian Migration Study Physical Activity Questionnaire (IMS-PAQ) in urban and rural groups in India. METHODS: A sub-sample of IMS participants (n = 479) was used to examine short term (≤ 1 month [n = 158]) and long term (> 1 month [n = 321]) IMS-PAQ reliability for levels of total, sedentary, light and moderate/vigorous activity (MVPA) intensity using intraclass correlation (ICC) and kappa coefficients (k). Criterion validity (n = 157) was examined by comparing the IMS-PAQ to a uniaxial accelerometer (ACC) worn ≥ 4 days, via Spearman's rank correlations (ρ) and k, using Bland-Altman plots to check for systematic bias. Construct validity (n = 7,000) was established using linear regression, comparing IMS-PAQ against theoretical constructs associated with physical activity (PA): BMI [kg/m2], percent body fat and pulse rate. RESULTS: IMS-PAQ reliability ranged from ICC 0.42-0.88 and k = 0.37-0.61 (≤ 1 month) and ICC 0.26 to 0.62; kappa 0.17 to 0.45 (> 1 month). Criterion validity was ρ = 0.18-0.48; k = 0.08-0.34. Light activity was underestimated and MVPA consistently and substantially overestimated for the IMS-PAQ vs. the accelerometer. Criterion validity was moderate for total activity and MVPA. Reliability and validity were comparable for urban and rural participants but lower in women than men. Increasing time spent in total activity or MVPA, and decreasing time in sedentary activity were associated with decreasing BMI, percent body fat and pulse rate, thereby demonstrating construct validity. CONCLUSION: IMS-PAQ reliability and validity is similar to comparable self-reported instruments. It is an appropriate tool for ranking PA of individuals in India. Some refinements may be required for sedentary populations and women in India.

Socio-demographic patterning of physical activity across migrant groups in India: results from the Indian Migration Study.

OBJECTIVE: To investigate the relationship between rural to urban migration and physical activity (PA) in India. METHODS: 6,447 (42% women) participants comprising 2077 rural, 2,094 migrants and 2,276 urban were recruited. Total activity (MET hr/day), activity intensity (min/day), PA Level (PAL) television viewing and sleeping (min/day) were estimated and associations with migrant status examined, adjusting for the sib-pair design, age, site, occupation, education, and socio-economic position (SEP). RESULTS: Total activity was highest in rural men whereas migrant and urban men had broadly similar activity levels (p<0.001). Women showed similar patterns, but slightly lower levels of total activity. Sedentary behaviour and television viewing were lower in rural residents and similar in migrant and urban groups. Sleep duration was highest in the rural group and lowest in urban non-migrants. Migrant men had considerably lower odds of being in the highest quartile of total activity than rural men, a finding that persisted after adjustment for age, SEP and education (OR 0.53, 95% CI 0.37, 0.74). For women, odds ratios attenuated and associations were removed after adjusting for age, SEP and education. CONCLUSION: Our findings suggest that migrants have already acquired PA levels that closely resemble long-term urban residents. Effective public health interventions to increase PA are needed.

Micronutrient supplementation improves physical performance measures in Asian Indian school-age children.

Micronutrients are important in physical work capacity and therefore performance. The impact of a multi-micronutrient-fortified nutritional beverage on physical performance measures among clinically healthy school-age children was assessed in a double-blind (for test and placebo groups), placebo-controlled, randomized trial in children aged between 7 and 10.5 y (n = 300). The participants with height- and weight-for-age Z-scores between 0 and ≥ -3 were randomized to 1 of 3 study arms: fortified choco-malt beverage powder (F), matched energy equivalent unfortified placebo (U), and untreated control (C). Participants in the F and C groups were given 40 g fortified (19 key vitamins and minerals) and unfortified choco-malt beverage, respectively, daily for 120 d. Primary efficacy outcomes included endurance and aerobic capacity using a 20-m shuttle test and step test. Other physical performance measures included speed (40-m sprint), visual reaction time, maximal hand grip, and forearm static endurance. Micronutrient status included thiamin, riboflavin, folate, niacin, iron, pyridoxal phosphate, and vitamins B-12 and C. All measurements were made at baseline and the end of the intervention. There was a within-subject increase in aerobic capacity and whole body endurance (P < 0.05) accompanied by a significant improvement in the status of iron thiamin, riboflavin, pyridoxal phosphate, folate, and vitamins C and B-12 in the F group compared to the within-subject changes in the other 2 groups (P < 0.05). The study suggests that multiple micronutrient supplementation in similar populations may be beneficial in improving micronutrient status and enhancing aerobic capacity and endurance in children.

Dietary intake and rural-urban migration in India: a cross-sectional study.

BACKGROUND: Migration from rural areas of India contributes to urbanisation and lifestyle change, and dietary changes may increase the risk of obesity and chronic diseases. We tested the hypothesis that rural-to-urban migrants have different macronutrient and food group intake to rural non-migrants, and that migrants have a diet more similar to urban non-migrants. METHODS AND FINDINGS: The diets of migrants of rural origin, their rural dwelling sibs, and those of urban origin together with their urban dwelling sibs were assessed by an interviewer-administered semi-quantitative food frequency questionnaire. A total of 6,509 participants were included. Median energy intake in the rural, migrant and urban groups was 2731, 3078, and 3224 kcal respectively for men, and 2153, 2504, and 2644 kcal for women (p<0.001). A similar trend was seen for overall intake of fat, protein and carbohydrates (p<0.001), though differences in the proportion of energy from these nutrients were <2%. Migrant and urban participants reported up to 80% higher fruit and vegetable intake than rural participants (p<0.001), and up to 35% higher sugar intake (p<0.001). Meat and dairy intake were higher in migrant and urban participants than rural participants (p<0.001), but varied by region. Sibling-pair analyses confirmed these results. There was no evidence of associations with time in urban area. CONCLUSIONS: Rural to urban migration appears to be associated with both positive (higher fruit and vegetables intake) and negative (higher energy and fat intake) dietary changes. These changes may be of relevance to cardiovascular health and warrant public health interventions.

Heart rate and systolic blood pressure variability: the impact of thinness and aging in human male subjects.

BACKGROUND: Life spans are steadily increasing in developing countries where 'thinness' is widely prevalent. However, the interaction of aging and thinness has been poorly studied in terms of its physiological consequences. OBJECTIVE: To determine the impact of aging and 'thinness' (body mass index (BMI) < 18.5 kg/m2) on resting heart rate and systolic blood pressure (SBP) variability indices in the frequency domain. SUBJECTS: Ninety seven healthy male subjects were divided into two age categories; young; 18-30 yrs and old superior 60 yrs. The subjects were further divided on the basis of BMI into young, thin (n=32), young, normal BMI (BMI 18.5-25, n = 27), old, thin (n = 15) and old, normal BMI (n = 23) groups. METHODS: Cardiac autonomic nerve function was determined using heart rate variability indices in the frequency domain (low frequency, cardiac sympathetic 0.04- 0.15 Hz; high frequency, cardiac parasympathetic 0.15-0.4 Hz). Vasomotor sympathetic activity was determined from the low frequency component of SBP variability. Baroreflex sensitivity was determined from the spectral power of both RR variability and SBP variability between 0.07 to 0.14 Hz. RESULTS: Thinness was associated with a reduction in the absolute total, low and high frequency heart rate power spectrum as compared to individuals of normal BMI, but this difference was only apparent in young adults (P < 0.05) and not in older subjects. The age related decline in heart rate variability (absolute units) was apparent for subjects of both low and normal BMI (P < 0.05). There were no differences in SBP variability either with age or BMI. CONCLUSIONS: The data suggest that aging has a pronounced effect on heart rate variability, which may mask differences in heart rate variability related to thinness.

How sedentary are people in "sedentary" occupations? The physical activity of teachers in urban South India.

AIMS: The aim of this study was to assess the total and occupational physical activity status of school and college teachers in Bangalore, South India and to evaluate the use of "job description" as an indicator of occupational physical activity. METHOD: A self-administered questionnaire was given to a convenience sample of 198 (25 males and 173 females) school and college teachers. RESULTS: Despite the categorization of "teacher" in India as "sedentary", our data indicate that the overall physical activity status of teachers varies considerably and is dependent on non-occupational physical activity, such as household chores and discretionary exercise. Thus, only 12% of teachers were truly sedentary, based on computations of the contributions of all measured physical activity domains, while 10% were heavily active. The contribution of other physical activity domains to the overall physical activity status in our data set was dependent on gender; in women, the energy expenditure related to household chores was 4-fold higher than in men (P < 0.01), while in men, energy expenditure related to discretionary exercise was 3-fold higher than in women (P < 0.01). CONCLUSIONS: This study highlights the problems associated with extrapolating occupational activity using job descriptors to overall physical activity status. The findings have implications in epidemiological studies which use occupational activity as a surrogate for overall physical activity status. However, the impact of potential misclassifications will need to be assessed within a socio-cultural context.

Effect of age and nutritional status on heart rate responses to cough and maximum handgrip.

Autonomic nerve activity can be assessed using simple bed side tests such as cough and maximum hand grip (MHG). The alterations in these tests are, however, poorly documented in physiological states. The present study aimed to uncover the effect of nutritional status and age on these tests. 93 male adults were divided into normal body mass index (BMI) (BMI; 18.5 to 25 kg/m2; young 18-30 yrs, n=28; old >60 yrs, n=25) and low BMI (BMI; <18.5 kg/m2; young 18-30 yrs, n=19; old >60 yrs, n=14) groups. The younger subjects showed a significantly higher heart rate response to cough and MHG in both normal and low BMI groups as compared to the older subjects (P<0.01). However, there were no significant differences for the heart rate responses to cough and MHG between the low and normal BMI groups either in the young or in the elderly. The data suggest that while the heart rate response to cough and MHG are useful tests of vagal activity to the heart when expected differences are large, they may be of limited use in uncovering more subtle changes.

Physical activity and risk of coronary heart disease in India.

BACKGROUND: Physical exercise has been inversely associated with coronary heart disease (CHD) risk in Western populations; however, the association has not been examined in India where physical inactivity levels in urban areas are now comparable with the West. METHODS: We conducted a hospital-based case-control study and collected data from 350 cases of acute myocardial infarction and 700 controls matched on age, gender, and hospital in New Delhi and Bangalore. We used conditional logistic regression to control for the matching and other risk factors. RESULTS: Of the controls, 48% participated in some form of leisure-time exercise compared with 38% of cases. In age- and sex-adjusted analyses, people in the highest level of leisure-time exercise (>145 metabolic equivalents [MET]-minutes per day, equivalent to 36 minutes of brisk walking per day) had a relative risk of 0.45 (95% CI: 0.31, 0.66) compared with non-exercisers. Multivariate adjustment for other risk factors did not substantially alter the association. We observed a positive association between non-work sedentary activity and CHD risk; people with >3.6 hours per day of sedentary activity (for example, television viewing) had an elevated risk of 1.88 (95% CI: 1.09, 3.20) compared with <70 minutes per day in multivariate analysis. CONCLUSION: Leisure-time exercise, including as much as 35-40 minutes per day of brisk walking, was protective for CHD risk and sedentary lifestyles were positively associated with risk of CHD. Given limited resources for care of CHD in India and the important role of physical exercise in disease risk in urban India, improvements in physical activity should be promoted.

Perceptions of the intensity of specific physical activities in Bangalore, South India: implications for exercise prescription.

OBJECTIVE: To assess perceptions of the intensity of specific physical activities in urban Indians and to determine whether these perceptions are dependent on age, gender, body mass index and actual physical patterns. METHOD: A self-administered questionnaire in a convenience sample of 782 adults (441 women) aged 17 to 70 years in the city of Bangalore. RESULTS: Women rated the intensity of carpentry, jogging, manual labour and walking uphill significantly higher than men. These differences persisted when they were adjusted for total daily physical activity levels and levels of discretionary exercise. In contrast, while men rated household activities such as manual washing of clothes and sweeping at higher levels than women, these differences disappeared when they were adjusted for actual levels of daily activity related to household chores. There were clear age-related changes in the perception of intensity of physical activities and these persisted even after adjustment for overall physical activity patterns. CONCLUSIONS: This study demonstrates clear age and gender-related differences in the perception of physical activities. This is important to know while motivating individuals to change physical activity patterns and assumes added importance given the recent evidence that perceived intensity of habitual activity is predictive of coronary heart disease, even at levels of activity that are below standard recommendations.

Heart rate variability and baroreflex sensitivity are reduced in chronically undernourished, but otherwise healthy, human subjects.

Alterations in autonomic nerve activity in subjects in a chronically undernourished state have been proposed, but have been inadequately documented. The present study evaluated heart rate and systolic blood pressure variability in the frequency domain in two underweight groups, one of which was undernourished and recruited from the lower socio-economic strata [underweight, undernourished (UW/UN); n =15], while the other was from a high class of socio-economic background [underweight, well nourished (UW/WN); n =17], as well as in normal-weight controls [normal weight, well nourished (NW/WN); n =27]. Baroreflex sensitivity, which is a determinant of heart rate variability, was also assessed. The data indicate that total power (0-0.4 Hz), low-frequency power (0.04-0.15 Hz) and high-frequency power (0.15-0.4 Hz) of RR interval variability were significantly lower in the UW/UN subjects ( P <0.05) than in the NW/WN controls when expressed in absolute units, but not when the low- and high-frequency components were normalized for total power. Baroreflex sensitivity was similarly lower in the UW/UN group ( P <0.05). Heart rate variability parameters in the UW/WN group were generally between those of the UW/UN and NW/WN groups, but were not statistically different from either. The mechanisms that contribute to the observed differences between undernourished and normal-weight groups, and the implications of these differences, remain to be elucidated.

A comparative study of tests of cardiac parasympathetic nervous activity in healthy human subjects.

Conventional tests of cardiac parasympathetic nervous system (PNS) activity were compared with the high frequency component of the heart rate power spectrum in a heterogenous group of normal subjects encompassing a wide age range. The data suggest that the linear associations between the various conventional tests of parasympathetic nervous activity even when statistically significant, were relatively modest, with r values ranging from 0.23 to 0.53. Three of the five conventional tests of parasympathetic nervous activity were significantly correlated (r = 0.33 to 0.46) with the absolute high frequency power of RR variability. However, these relationships were poorer and non-significant when the high frequency power spectrum was normalized for total power (r = 0.06 to 0.19, NS). An evaluation of the heart rate responses to cough and a single maximal hand grip indicated that the responses were repeatable but that the extent to which these manoeuvres induced vagally mediated cardioacceleration was significantly lesser than the other conventional tests of PNS activity. Taken together, the data suggest that despite the advent of heart rate variability measures, it is advisable to use multiple tests of parasympathetic nervous activity while evaluating autonomic dysfunction, since, despite the specificity of the tests, there is a variable correlation between them.

Practices and perceptions of physical activity in urban, employed, middle-class Indians.

The aim of this study was to describe the detailed physical activity profiles of educated, employed, urban Indians and to ascertain their knowledge about the benefits of exercise, their concept of 'ideal' exercise, and the constraints in achieving it. To this end, 401 subjects (193 males, 208 females) between the ages of 25 and 58 years were studied. Women were significantly more active than men (p < 0.05), largely due to enhanced household activity (p < 0.05), which was not offset by the higher leisure time-related exercise of males (p < 0.05). Over 50 percent of subjects were aware of the benefits of exercise in preventing heart disease. The subjects' perceptions of 'ideal' exercise, based on exercise programmes they had drawn up for themselves, were adequate in terms of frequency and duration, but inadequate in intensity, when compared with the current recommendations for exercise in primary prevention of coronary heart disease. Lack of time (men 53.4%, women 68.3%) and lack of motivation (men 26.4%, women 28.4%) were the most-often cited reasons for being unable to achieve 'ideal' exercise goals. The data provides an important framework for understanding physical activity profiles of urban, educated and employed Indians on the basis of which behavioural strategies can be formulated to enhance physical activity and reduce cardiovascular risk.

The development & characteristics of a physical activity questionnaire for epidemiological studies in urban middle class Indians.

A single page physical activity questionnaire was designed for use in epidemiological studies. The questionnaire estimates 24 h energy expenditure as well as components of occupation and discretionary leisure time activities. Estimates of physical activity were highly repeatable, when the questionnaire was re-administered within a 4 wk period (e.g., r = 0.86, P < 0.01 for 24 h energy expenditure). Relative validity was assessed by comparing energy intake (using repeated 24 h dietary recalls) and expenditure (using the physical activity questionnaire) over the same period. A correlate of r = 0.33, P < 0.05 between the two measures compared well with reports from literature. The discriminatory power of the questionnaire was assessed by comparing the physical activity patterns of young (18-30 yr) and older (> 60 yr), free living healthy subjects. The questionnaire provides a tool for the assessment of physical activity patterns of urban middle class Indians, which despite its importance has been inadequately studied so far.

Gender differences in muscle strength & endurance in young Indian adults.

Muscle strength was studied in 70 males and 53 females between the ages of 17-30 yr, using a handgrip dynamometer. In a subset group of 31 males and 20 females, muscle endurance during sustained isometric contraction was studied using a load cell based handgrip dynamometer coupled to a polygraph. The males had a significantly greater muscle mass and lower body fat as compared to the females. Males had close to twice the handgrip strength of females in absolute terms (P < 0.01) and this difference persisted after correction for forearm muscle area (P < 0.05). In contrast, the rate of decline of muscle strength during sustained isometric contraction was lower in females as compared to males (P < 0.05), suggestive of greater skeletal muscle endurance in females. Physical activity patterns were not a determinant of skeletal muscle function. These findings are consistent with gender specific muscle fibre characteristics reported in literature in other racial groups.