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Journal of the American College of Nutrition Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uacn20
Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen a
a
a
a
a
Min Mu MD , Su-Fang Wang MD , Jie Sheng PhD , Yan Zhao MD , Guo-Xiu Wang MD , a
a
b
Kai-Yong Liu PhD , Chuan-Lai Hu PhD , Fang-Biao Tao PhD & Hai-Lin Wang MD
c
a
Department of Nutrition , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA b
Department of Maternal, Child & Adolescent Health, School of Public Health , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA c
Click for updates
Department of University Hospital , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA Published online: 14 Apr 2014.
To cite this article: Min Mu MD , Su-Fang Wang MD , Jie Sheng PhD , Yan Zhao MD , Guo-Xiu Wang MD , Kai-Yong Liu PhD , Chuan-Lai Hu PhD , Fang-Biao Tao PhD & Hai-Lin Wang MD (2014) Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen, Journal of the American College of Nutrition, 33:2, 120-128, DOI: 10.1080/07315724.2013.874897 To link to this article: http://dx.doi.org/10.1080/07315724.2013.874897
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Original Research
Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Min Mu, MD, Su-Fang Wang, MD, Jie Sheng, PhD, Yan Zhao, MD, Guo-Xiu Wang, MD, Kai-Yong Liu, PhD, Chuan-Lai Hu, PhD, Fang-Biao Tao, PhD, Hai-Lin Wang, MD Department of Nutrition (M.M., S.-F.W., J.S., Y.Z., G.-X.W., K.-Y.L., C.-L.H.), Department of Maternal, Child & Adolescent Health, School of Public Health (F.B.T.), Department of University Hospital (H.-L.W.), Anhui Medical University, Hefei Province, PEOPLE’S REPUBLIC OF CHINA Key words: dietary pattern, body mass index (BMI), bone mineral density (BMD), freshmen Objective: Our objective was to examine associations between dietary patterns and body mass index (BMI) and bone mineral density (BMD) in Chinese freshmen. Methods: A cross-sectional study was done in 1319 college freshmen (aged 18.1 ± 1.2 years old). Diet was assessed by using a validated self-administrated food-frequency questionnaire. Blood pressure, weight, height, waist circumference, and hip circumference were measured and bone measurements were done using Quantitative Ultrasound System. Results: Four dietary patterns were identified by factor analysis: Western food, animal protein, calcium food, and Chinese traditional patterns. The prevalence of overweight/obesity and osteopenia/osteoporosis were 8.2% (108/1319) and 28.1% (371/1319). The highest tertile of Western food pattern scores had greater odds of overweight/obesity (highest vs. lowest tertile, odds ratio [OR] = 2.00, 95% confidence interval [CI], 1.24–3.22), and the highest tertile of Chinese traditional pattern scores had lower risk of overweight/obesity (highest vs. lowest tertile, OR = 0.65, 95% CI, 0.53–0.80) in an adjusted model. The calcium food pattern and Chinese traditional pattern were negatively associated with the risk of osteopenia/osteoporosis (highest vs. lowest tertile, OR = 0.59, 95% CI, 0.41–0.87; OR = 0.78, 95% CI, 0.55–0.89) after adjusting for confounders. Conclusion: These findings suggested that there was a positive correlation between Chinese traditional dietary pattern and healthy BMI and BMD and that this same association existed between calcium food pattern and BMD in Chinese freshmen. In contrast, the Western-style diet was negatively correlated with healthy BMI in Chinese freshmen.
INTRODUCTION
of osteoporosis and fracture in the elderly [4]. However, little attention has been given to preventative strategies for this population. Preventive measures that can promote low body fat and high BMD early in life are needed to reduce the public health burden of obesity and osteoporosis. However, there is a notable scarcity of studies in adolescents or young adults that evaluated dietary intakes that simultaneously optimize body mass index (BMI) and BMD. Such studies are needed to discern the effects of dietary intake and to inform practitioners to support appropriate growth and BMI and bone mass accrual in adolescence. Previous studies have mostly considered diet in terms of food groups (e.g., fruit and vegetables) or its content of single nutrient (e.g., dietary fat or fiber) or single food [5,6].
Obesity and osteoporosis are related to significant morbidity and mortality. Both diseases may contribute to low quality of life and increase the public health burden [1]. The 2002 China National Nutrition and Health Survey indicated that the prevalence of overweight and obesity was 22.8% and 7.1% in Chinese adults [2]. In addition, it was estimated that about 88 million people were suffering from primary osteoporosis, and one in 3 women in China over aged 50 years would experience osteoporotic fractures [3]. Low bone mineral density (BMD) during adolescence or early adulthood and premature bone loss would lead to failure to attain the optimal peak bone mass and finally increase the risk
Address correspondence to: Su-Fang Wang, Department of Nutrition, School of Public Health, Anhui Medical University, 81 Meishan Rd., Hefei Province, Anhui 230032, PEOPLE’S REPUBLIC OF CHINA. E-mail: [email protected] Abbreviations: BMI = body mass index; BMD = bone mineral density; FFQ = Food Frequency Questionnaire; WHR = waist-to-hip ratio; IPAQ-C = International Physical Activity Questionnaire.
Journal of the American College of Nutrition, Vol. 33, No. 2, 120–128 (2014) C American College of Nutrition Published by Taylor & Francis Group, LLC 120
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Dietary Patterns and BMI However, given the complexity of human diets, the high correlations between intakes of various nutrients or food items, and the many nutrient-to-nutrient biochemical interactions, results describing the effects of consumption levels of single nutrient or food on a given health outcome may be spurious [7]. Therefore, a measurement of the overall pattern of dietary intake may have a greater potential for being associated with health outcomes than any single component [8]. Dietary pattern analysis, which reflects the complexity of dietary intake, has recently received more attention from nutritional epidemiologists [9,10]. A dietary pattern approach can summarize complex dietary data into more practical and meaningful information. Otherwise, an epidemiological nutrient approach is not directly related to dietary recommendation, because individuals ultimately determine nutrient intake largely by their choice of different foods [11]. Thus, it is more useful to give advice on dietary patterns than nutrients in nutrition intervention planning. Although the importance of adolescent diet for lifelong health is increasingly recognized, there is little information about what constitutes a diet that promotes healthy BMI and BMD during adolescence. Our primary objective was to examine associations between dietary patterns and BMI and BMD in Chinese freshmen.
MATERIALS AND METHODS Participants We selected subjects from 4 universities. A total of 1414 freshmen entering school in September 2010 were enrolled. The survey was carried out in September 2010 and 1319 freshmen completed the questionnaire and were included in the study; another 81 freshmen who did not finish the questionnaire and 14 freshmen with diseases/medication (such as glucocorticoids, dermatomyositis) known to influence body composition or BMD were excluded. Students were provided monetary compensation for completing assessments. The study was approved by the Ethics Committee of Anhui Medical University, and all participants provided written informed consent.
Assessment of Dietary Intake Dietary intake was assessed by the use of a modified food frequency questionnaire (FFQ). According to the dietary features of the target population, the FFQ was modified on the basis of a previous questionnaire [12]. The FFQ contains 19 food groups that Chinese people often eat. Each item represents a food group, and participants were asked how often (daily, weekly, monthly, annually, or never) they consumed each food group. We assessed the reliability and validity of the FFQ. For the reliability test, we chose 30 students from a small class to complete the FFQ, and after one month we conducted the second FFQ survey (FFQ1
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION
and FFQ2). The Pearson correlation coefficients of the comparison of the 2 FFQs ranged between 0.71 and 0.89 for major food groups. For the validity test, after the first investigation, the FFQ was validated by a pilot survey within the same population by comparison with three 24-hour dietary recalls before the study, and the correlation coefficients between the FFQ and averages from 24-hour dietary recalls ranged between 0·41 and 0·69 for major food groups. Overall, these data indicated that the FFQ provided reasonably valid measurements of dietary intakes. A trained dietitian administered the entire questionnaire. Participants were asked how often they had consumed each food group over the past year. Subjects responded in 3 frequency consumption categories: daily (core food), weekly (secondary core food), or monthly (peripheral food). Each consumption category was scored as follows: never eat = 0; 1–3 times = 1; 4–5 times = 2; 6–8 times = 3; and more than 8 times = 4. This article focuses only on the frequency of each food item, and information on the portion size is not included.
Assessment of Anthropometric Measures Weight was measured with a Seca scale (HW - 700, Kai Yuan Corporation, Zheng Zhou, China) and recorded to the nearest 100 g. Height was measured with a Seca stadiometer (HW – 700, Kai Yuan Corporation, Zheng Zhou, China) while the subjects were in a standing position with their shoulders in normal position. BMI was computed as weight (kilograms) divided by height (meters) squared. According to the Working Group on Obesity in China, obesity was defined as a BMI of at least 28 kg/m2, and overweight was defined as 24 kg/m2 ≤ BMI < 28 kg/m2 [13]. Waist circumference was measured to the narrowest level between the lowest rib and the iliac crest. Hip circumference was measured at the maximum level over light clothing using an outstretched tape measure. Measurements were recorded to the nearest 0.1 cm. Waist-to-hip ratio was calculated. We defined central adiposity as waist circumference > 85 cm for men and waist circumference > 80 cm for women [14]. Participants were made to rest for 15 minutes before their blood pressure was measured. A qualified physician then measured the blood pressure of a seated subject twice with a standard mercury sphygmomanometer, and thereafter the mean of 2 measurements was considered the participant’s blood pressure. Systolic blood pressure was defined as the appearance of the first sound (Korotkoff phase 1), and the diastolic blood pressure was defined as the disappearance of the sound (Korotkoff phase 5) during deflation of the cuff at a decrement rate of 2 to 3 mm/s of the mercury column. Elevated blood pressure was defined as systolic blood pressure > 120 mmHg and/or diastolic blood pressure > 80 mmHg, and hypertension was defined as systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg [15].
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Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Dietary Patterns and BMI Speed of sound (SOS) was measured in the subjects using an ultrasound bone densitometer (CM-200, Furuno Electric Corporation, Hyogo Nishinomiya, Japan) on the right calcaneus. After inputting the name, age, gender, and other relevant data and disinfecting the right foot with both sides, we measured the SOS. SOS refers to the speed of the sound wave traveling through the calcaneus, measured in meters per second. All measurements were made 2 times. A T value is used to evaluate the risk of osteoporosis. T value = (the SOS of subjects − the peak SOS of normal young people)/SD (standard deviation of SOS of normal young people). The epidemiological diagnosis standards [16] are as follows: A T value more than −1.0 is regarded as normal, a T value more than −2.50 and less than −1.0 is diagnosed as osteopenia, and a T value less than −2.50 is diagnosed as osteoporosis.
Assessment of Other Variables The Chinese version of the International Physical Activity Questionnaire was used to measure the physical activity of this population, and the reliability and validity of the questionnaire has been examined. Physical activity can be divided into 3 grades: strenuous exercise, medium-intensity exercise, and lowintensity exercise [17]. Data on physical activity were obtained by using participants’ responses to a simple question. How much time do you exercise in a week? We categorized the responses to this question as never, 0.30 are provided in bold.
There were more male participants (p < 0.05), participants who participated in strenuous exercise (p < 0.05), and participants who took calcium supplements (p < 0.001) in the highest tertile than in the lowest tertile of the calcium food pattern. Those in the highest tertile of the Chinese traditional pattern took calcium supplements more often.
Distribution of Anthropometric Characteristics Multivariate-adjusted (adjusted for sex, physical activity, economic status, passive smoking, drinking, calcium supplements, BMD further adjusted for BMI) means of anthropometric measurements across tertiles of the major dietary patterns are listed in Table 4. After adjustment for potential
Table 2. The 19 Food Groupings Used in the Dietary Pattern Analysis1 Food Group Grains Fresh vegetables Fresh fruits Pork Mutton and beef Poultry meat Animal liver Eggs Fish and shrimp Marine products Dairy products Beans and bean products Hamburger and fried food Pickled food Nuts Snack food Cola Coffee Sugars 1
Foods in the Group Wheat, rice, corn, sorghum, potato (boiled or baked) Carrots, tomatoes, green pepper, broccoli, lettuce, green leafy vegetables such as spinach, cucumber, Chinese cabbage, onion, eggplant Oranges, bananas, apples, strawberries, grapes, peaches, pears, kiwi fruit, melons, watermelon Lard, fat and lean meat Fat and lean meat Chicken, duck, goose Pork liver and other types of liver Egg (including yolk) Carp, grass carp, silver carp, herring, shrimp Kelp laver, sea fish, seaweed Whole milk, low-fat milk, skim milk, yogurt, cheese, cottage cheese, lactic acid bacteria–containing beverages, ice cream Red bean, green beans, black beans, soybean, bean curd, bean sprouts, soya-bean milk Youtiao, oil cake, fried chicken, chip, hamburger Sausage, ham, pickled vegetables, pickled meat, salted egg Peanut, walnut, melon seed, cashew Chocolate, cake, biscuit Cola Coffee Candy, cookie
Foods listed in the table are from the self-administered diet questionnaire.
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION
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Dietary Patterns and BMI Table 3. Characteristics of the Study Participants across Tertiles of Major Dietary Patterns: Freshmen (n = 1319) Aged 16–20 Years, Hefei, China, 20101
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Male (%) Yes No Rural (%) Yes No ePlace for meals (%) Canteen Eatery or at home Family incomes (%) Wealthy General Poor Passive smoking (%) Yes No Drinking (%) Yes No Physical activity (%) Strenuous exercise2
Journal of the American College of Nutrition Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uacn20
Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen a
a
a
a
a
Min Mu MD , Su-Fang Wang MD , Jie Sheng PhD , Yan Zhao MD , Guo-Xiu Wang MD , a
a
b
Kai-Yong Liu PhD , Chuan-Lai Hu PhD , Fang-Biao Tao PhD & Hai-Lin Wang MD
c
a
Department of Nutrition , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA b
Department of Maternal, Child & Adolescent Health, School of Public Health , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA c
Click for updates
Department of University Hospital , Anhui Medical University , Hefei Province , PEOPLE’S REPUBLIC OF CHINA Published online: 14 Apr 2014.
To cite this article: Min Mu MD , Su-Fang Wang MD , Jie Sheng PhD , Yan Zhao MD , Guo-Xiu Wang MD , Kai-Yong Liu PhD , Chuan-Lai Hu PhD , Fang-Biao Tao PhD & Hai-Lin Wang MD (2014) Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen, Journal of the American College of Nutrition, 33:2, 120-128, DOI: 10.1080/07315724.2013.874897 To link to this article: http://dx.doi.org/10.1080/07315724.2013.874897
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Original Research
Dietary Patterns Are Associated with Body Mass Index and Bone Mineral Density in Chinese Freshmen
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Min Mu, MD, Su-Fang Wang, MD, Jie Sheng, PhD, Yan Zhao, MD, Guo-Xiu Wang, MD, Kai-Yong Liu, PhD, Chuan-Lai Hu, PhD, Fang-Biao Tao, PhD, Hai-Lin Wang, MD Department of Nutrition (M.M., S.-F.W., J.S., Y.Z., G.-X.W., K.-Y.L., C.-L.H.), Department of Maternal, Child & Adolescent Health, School of Public Health (F.B.T.), Department of University Hospital (H.-L.W.), Anhui Medical University, Hefei Province, PEOPLE’S REPUBLIC OF CHINA Key words: dietary pattern, body mass index (BMI), bone mineral density (BMD), freshmen Objective: Our objective was to examine associations between dietary patterns and body mass index (BMI) and bone mineral density (BMD) in Chinese freshmen. Methods: A cross-sectional study was done in 1319 college freshmen (aged 18.1 ± 1.2 years old). Diet was assessed by using a validated self-administrated food-frequency questionnaire. Blood pressure, weight, height, waist circumference, and hip circumference were measured and bone measurements were done using Quantitative Ultrasound System. Results: Four dietary patterns were identified by factor analysis: Western food, animal protein, calcium food, and Chinese traditional patterns. The prevalence of overweight/obesity and osteopenia/osteoporosis were 8.2% (108/1319) and 28.1% (371/1319). The highest tertile of Western food pattern scores had greater odds of overweight/obesity (highest vs. lowest tertile, odds ratio [OR] = 2.00, 95% confidence interval [CI], 1.24–3.22), and the highest tertile of Chinese traditional pattern scores had lower risk of overweight/obesity (highest vs. lowest tertile, OR = 0.65, 95% CI, 0.53–0.80) in an adjusted model. The calcium food pattern and Chinese traditional pattern were negatively associated with the risk of osteopenia/osteoporosis (highest vs. lowest tertile, OR = 0.59, 95% CI, 0.41–0.87; OR = 0.78, 95% CI, 0.55–0.89) after adjusting for confounders. Conclusion: These findings suggested that there was a positive correlation between Chinese traditional dietary pattern and healthy BMI and BMD and that this same association existed between calcium food pattern and BMD in Chinese freshmen. In contrast, the Western-style diet was negatively correlated with healthy BMI in Chinese freshmen.
INTRODUCTION
of osteoporosis and fracture in the elderly [4]. However, little attention has been given to preventative strategies for this population. Preventive measures that can promote low body fat and high BMD early in life are needed to reduce the public health burden of obesity and osteoporosis. However, there is a notable scarcity of studies in adolescents or young adults that evaluated dietary intakes that simultaneously optimize body mass index (BMI) and BMD. Such studies are needed to discern the effects of dietary intake and to inform practitioners to support appropriate growth and BMI and bone mass accrual in adolescence. Previous studies have mostly considered diet in terms of food groups (e.g., fruit and vegetables) or its content of single nutrient (e.g., dietary fat or fiber) or single food [5,6].
Obesity and osteoporosis are related to significant morbidity and mortality. Both diseases may contribute to low quality of life and increase the public health burden [1]. The 2002 China National Nutrition and Health Survey indicated that the prevalence of overweight and obesity was 22.8% and 7.1% in Chinese adults [2]. In addition, it was estimated that about 88 million people were suffering from primary osteoporosis, and one in 3 women in China over aged 50 years would experience osteoporotic fractures [3]. Low bone mineral density (BMD) during adolescence or early adulthood and premature bone loss would lead to failure to attain the optimal peak bone mass and finally increase the risk
Address correspondence to: Su-Fang Wang, Department of Nutrition, School of Public Health, Anhui Medical University, 81 Meishan Rd., Hefei Province, Anhui 230032, PEOPLE’S REPUBLIC OF CHINA. E-mail: [email protected] Abbreviations: BMI = body mass index; BMD = bone mineral density; FFQ = Food Frequency Questionnaire; WHR = waist-to-hip ratio; IPAQ-C = International Physical Activity Questionnaire.
Journal of the American College of Nutrition, Vol. 33, No. 2, 120–128 (2014) C American College of Nutrition Published by Taylor & Francis Group, LLC 120
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Dietary Patterns and BMI However, given the complexity of human diets, the high correlations between intakes of various nutrients or food items, and the many nutrient-to-nutrient biochemical interactions, results describing the effects of consumption levels of single nutrient or food on a given health outcome may be spurious [7]. Therefore, a measurement of the overall pattern of dietary intake may have a greater potential for being associated with health outcomes than any single component [8]. Dietary pattern analysis, which reflects the complexity of dietary intake, has recently received more attention from nutritional epidemiologists [9,10]. A dietary pattern approach can summarize complex dietary data into more practical and meaningful information. Otherwise, an epidemiological nutrient approach is not directly related to dietary recommendation, because individuals ultimately determine nutrient intake largely by their choice of different foods [11]. Thus, it is more useful to give advice on dietary patterns than nutrients in nutrition intervention planning. Although the importance of adolescent diet for lifelong health is increasingly recognized, there is little information about what constitutes a diet that promotes healthy BMI and BMD during adolescence. Our primary objective was to examine associations between dietary patterns and BMI and BMD in Chinese freshmen.
MATERIALS AND METHODS Participants We selected subjects from 4 universities. A total of 1414 freshmen entering school in September 2010 were enrolled. The survey was carried out in September 2010 and 1319 freshmen completed the questionnaire and were included in the study; another 81 freshmen who did not finish the questionnaire and 14 freshmen with diseases/medication (such as glucocorticoids, dermatomyositis) known to influence body composition or BMD were excluded. Students were provided monetary compensation for completing assessments. The study was approved by the Ethics Committee of Anhui Medical University, and all participants provided written informed consent.
Assessment of Dietary Intake Dietary intake was assessed by the use of a modified food frequency questionnaire (FFQ). According to the dietary features of the target population, the FFQ was modified on the basis of a previous questionnaire [12]. The FFQ contains 19 food groups that Chinese people often eat. Each item represents a food group, and participants were asked how often (daily, weekly, monthly, annually, or never) they consumed each food group. We assessed the reliability and validity of the FFQ. For the reliability test, we chose 30 students from a small class to complete the FFQ, and after one month we conducted the second FFQ survey (FFQ1
JOURNAL OF THE AMERICAN COLLEGE OF NUTRITION
and FFQ2). The Pearson correlation coefficients of the comparison of the 2 FFQs ranged between 0.71 and 0.89 for major food groups. For the validity test, after the first investigation, the FFQ was validated by a pilot survey within the same population by comparison with three 24-hour dietary recalls before the study, and the correlation coefficients between the FFQ and averages from 24-hour dietary recalls ranged between 0·41 and 0·69 for major food groups. Overall, these data indicated that the FFQ provided reasonably valid measurements of dietary intakes. A trained dietitian administered the entire questionnaire. Participants were asked how often they had consumed each food group over the past year. Subjects responded in 3 frequency consumption categories: daily (core food), weekly (secondary core food), or monthly (peripheral food). Each consumption category was scored as follows: never eat = 0; 1–3 times = 1; 4–5 times = 2; 6–8 times = 3; and more than 8 times = 4. This article focuses only on the frequency of each food item, and information on the portion size is not included.
Assessment of Anthropometric Measures Weight was measured with a Seca scale (HW - 700, Kai Yuan Corporation, Zheng Zhou, China) and recorded to the nearest 100 g. Height was measured with a Seca stadiometer (HW – 700, Kai Yuan Corporation, Zheng Zhou, China) while the subjects were in a standing position with their shoulders in normal position. BMI was computed as weight (kilograms) divided by height (meters) squared. According to the Working Group on Obesity in China, obesity was defined as a BMI of at least 28 kg/m2, and overweight was defined as 24 kg/m2 ≤ BMI < 28 kg/m2 [13]. Waist circumference was measured to the narrowest level between the lowest rib and the iliac crest. Hip circumference was measured at the maximum level over light clothing using an outstretched tape measure. Measurements were recorded to the nearest 0.1 cm. Waist-to-hip ratio was calculated. We defined central adiposity as waist circumference > 85 cm for men and waist circumference > 80 cm for women [14]. Participants were made to rest for 15 minutes before their blood pressure was measured. A qualified physician then measured the blood pressure of a seated subject twice with a standard mercury sphygmomanometer, and thereafter the mean of 2 measurements was considered the participant’s blood pressure. Systolic blood pressure was defined as the appearance of the first sound (Korotkoff phase 1), and the diastolic blood pressure was defined as the disappearance of the sound (Korotkoff phase 5) during deflation of the cuff at a decrement rate of 2 to 3 mm/s of the mercury column. Elevated blood pressure was defined as systolic blood pressure > 120 mmHg and/or diastolic blood pressure > 80 mmHg, and hypertension was defined as systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg [15].
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Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Dietary Patterns and BMI Speed of sound (SOS) was measured in the subjects using an ultrasound bone densitometer (CM-200, Furuno Electric Corporation, Hyogo Nishinomiya, Japan) on the right calcaneus. After inputting the name, age, gender, and other relevant data and disinfecting the right foot with both sides, we measured the SOS. SOS refers to the speed of the sound wave traveling through the calcaneus, measured in meters per second. All measurements were made 2 times. A T value is used to evaluate the risk of osteoporosis. T value = (the SOS of subjects − the peak SOS of normal young people)/SD (standard deviation of SOS of normal young people). The epidemiological diagnosis standards [16] are as follows: A T value more than −1.0 is regarded as normal, a T value more than −2.50 and less than −1.0 is diagnosed as osteopenia, and a T value less than −2.50 is diagnosed as osteoporosis.
Assessment of Other Variables The Chinese version of the International Physical Activity Questionnaire was used to measure the physical activity of this population, and the reliability and validity of the questionnaire has been examined. Physical activity can be divided into 3 grades: strenuous exercise, medium-intensity exercise, and lowintensity exercise [17]. Data on physical activity were obtained by using participants’ responses to a simple question. How much time do you exercise in a week? We categorized the responses to this question as never, 0.30 are provided in bold.
There were more male participants (p < 0.05), participants who participated in strenuous exercise (p < 0.05), and participants who took calcium supplements (p < 0.001) in the highest tertile than in the lowest tertile of the calcium food pattern. Those in the highest tertile of the Chinese traditional pattern took calcium supplements more often.
Distribution of Anthropometric Characteristics Multivariate-adjusted (adjusted for sex, physical activity, economic status, passive smoking, drinking, calcium supplements, BMD further adjusted for BMI) means of anthropometric measurements across tertiles of the major dietary patterns are listed in Table 4. After adjustment for potential
Table 2. The 19 Food Groupings Used in the Dietary Pattern Analysis1 Food Group Grains Fresh vegetables Fresh fruits Pork Mutton and beef Poultry meat Animal liver Eggs Fish and shrimp Marine products Dairy products Beans and bean products Hamburger and fried food Pickled food Nuts Snack food Cola Coffee Sugars 1
Foods in the Group Wheat, rice, corn, sorghum, potato (boiled or baked) Carrots, tomatoes, green pepper, broccoli, lettuce, green leafy vegetables such as spinach, cucumber, Chinese cabbage, onion, eggplant Oranges, bananas, apples, strawberries, grapes, peaches, pears, kiwi fruit, melons, watermelon Lard, fat and lean meat Fat and lean meat Chicken, duck, goose Pork liver and other types of liver Egg (including yolk) Carp, grass carp, silver carp, herring, shrimp Kelp laver, sea fish, seaweed Whole milk, low-fat milk, skim milk, yogurt, cheese, cottage cheese, lactic acid bacteria–containing beverages, ice cream Red bean, green beans, black beans, soybean, bean curd, bean sprouts, soya-bean milk Youtiao, oil cake, fried chicken, chip, hamburger Sausage, ham, pickled vegetables, pickled meat, salted egg Peanut, walnut, melon seed, cashew Chocolate, cake, biscuit Cola Coffee Candy, cookie
Foods listed in the table are from the self-administered diet questionnaire.
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Dietary Patterns and BMI Table 3. Characteristics of the Study Participants across Tertiles of Major Dietary Patterns: Freshmen (n = 1319) Aged 16–20 Years, Hefei, China, 20101
Downloaded by [University of Colorado at Boulder Libraries] at 22:13 24 December 2014
Male (%) Yes No Rural (%) Yes No ePlace for meals (%) Canteen Eatery or at home Family incomes (%) Wealthy General Poor Passive smoking (%) Yes No Drinking (%) Yes No Physical activity (%) Strenuous exercise2
