Asia Pacific J Clin Nutr (1994) 3, 145-148

Dietary habits, physical activity and body size among Chinese in North America and China

Marion M. Lee PhD

Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, CA, USA

We examined the self-reported dietary nutrient intakes, physical activity patterns and body mass index (BMI) of 2488 healthy Chinese men and women residing in North America (and Canada) and in the People's Republic of China. On average, Chinese in China consumed more total energy (males 3024 kcal in China, vs 2122 kcal in North America; females 2351 kcal in China. vs 1745 kcal in North America) and carbohydrate but less fat (males 74.s g in China vs 82.0 g in North America, females 56.0 g in China vs 68.8 g in North America), protein, vitamin A, b -carotene and vitamin C than did Chinese in North America. Dietary fat provided 35% of total dietary energy for Chinese in North America and 22% for Chinese in China. Consumption of alcohol, particularly wine and hard liquor, was higher among Chinese in China than Chinese in North America. Chinese in China reported more kilocalories of energy expenditure per day, especially in vigorous activity and walking, than Chinese in North America. Chinese in China weighed less and were leaner than North American Chinese. These differences in nutrient intakes, physical activity and body size of Chinese living in two different continents suggest possible explanations for observed differences in chronic disease rates in the two populations.

Introduction

Chinese in western countries exhibit higher rates of many chronic diseases than do Chinese in Asia^1,2. But there is a lack of data for comparisons of the environmental and lifestyle factors for Chinese in China and Chinese residing in western countries.

This report describes dietary intakes, physical activity and body mass of healthy Chinese in: Los Angeles County and the San Francisco Bay Area, California; Vancouver, British Columbia; and Hangzhou and Ningpo in Zhejiang province of the People's Republic of China.

Methods

The data were obtained from controls in a multicenter case control study of colorectal cancer conducted from 1984 through 1987³. In the United States and China, controls were randomly selected from neighbourhoods of cases. In Canada, controls were selected from a provincial government medical insurance registry that covers virtually the entire population of British Columbia. In North America, controls were stratified by low (<10 %) and high (³ 10 %) Chinese density (percentage of the population that is Chinese) in the census tract of residence. Detailed control selection methods have been described . Controls were matched to cases by age (five year groups) and sex. Cases in China were younger than those in North America, therefore controls from China are younger than those from North America (Table 1).

Table 1. Demographic characteristics of Chinese in North America and China.

	Men		Women
North America	China	North America	China
Sample size	698	678	494	618
Mean age (years) ± SE	66± 0.5	56± 0.5	62± 0.7	53± 0.5
% <6th grade education	23.6	63.8	46.0	80.3
% Low income(<10,000 In US; <l.000 in China)	28.4	17.6	28.4	22.0
% Born in Asia	89.8	100	90.3	100
Mean height (cm) ± SE	166.9± 0.3	167.4± 0.2	156.1± 0.3	157.4± 0.2
Mean weigh (kg) ± SE	63.4± 0.4	58.9± 0.3	54.1 ± 0.4	51.9± 0.3
Body Mass Index (kg/m2)	22.7± 0.1	21.0± 0.1	22.2± 0.2	20.9± 0.1

Participants in North America (n=l192) and in China (n=1296) were interviewed in their homes by trained interviewers in the language of their choice. The questionnaires were available in English and Mandarin or Cantonese; the questions pertained to residential history, birth place, education, household income, and length of residence in the United States or Canada. The dietary component of the questionnaire^3a consisted of 84 frequently consumed food items selected to represent calories and nutrients of interest with respect to colorectal cancer (total fat, protein, b -carotene, vitamin C, calcium, phosphorus, and dietary fiber). In China, the dietary component of the questionnaire excluded four items asked in North America (sweets, cheeses, mayonnaise and cream sauces) but included additional items on soybean products, and fruits and vegetables indigenous to this part of China. Subjects reported the average frequency and serving size for each of the foods consumed in the year prior to the interview .

Subjects were also asked their height, weight and activity patterns for the previous year. Physical measurements 1000 were not taken. Subjects estimated the amount of time they spent in four activities: sleeping; sitting; light or moderate activity; and vigorous activity during a typical 24-hour day. In addition, in North America, questions on miles walked per day and flights of stairs climbed per day were included; whereas in China, miles of bicycling per day were asked.

All data were edited, coded and checked for range and consistency. Nutrient values of food items were obtained from several standard sources in the United States^4-6 and in China⁷. An estimate of each subject's average intake of the nutrients was calculated by multiplying the frequency of intake by the serving size of each food consumed, and summing these quantities to obtain a single value for each nutrient^3a. We also calculated each subject's frequency of consumption of the following food groups: pork; beef; red meats (including beef, pork and lamb); dairy products; soybean products; vegetables; fruits; beers; wine; and hard liquor. Total energy (kcal) expenditures were estimated by assigning expenditure rates per minute specific to body weight for each of the four activity categories, then summing the four activities to obtain a single estimate of daily energy expenditure³. Descriptive statistics were calculated specific for gender and stratified by continent. We compared dietary intakes, physical activities and body mass across continents using two-tailed z tests⁸.

Results

Both men and women were less educated and lighter in China than in North America (Table 1). Body mass index (kg/m²) did not vary by sex on each continent. A majority of North American Chinese (90 %) were born in Asia, about 45 % of them lived in census tracts with low density (<10%) of Chinese suggesting greater acculturation in a Western lifestyle.

Males reported higher nutrient intakes than females in both countries (Table 2). Consumption of total energy and carbohydrate was higher in China than in North America. Consumption of total fat, protein, vitamin A, b -carotene, vitamin C and calcium was significantly lower in China than in North America (P<0.01). There were differences in the percentage of energy from protein (North America 18 %, China 10 %), fat (North America 35 %, China 22 %) and carbohydrates (North America 47 %, and China 68 %) in North America compared with Chinese.

Table 2. Mean (SE) daily intake of dietary nutrients among Chinese in North America and China.

	Men		Women
	North America	China	North America	China
	N=698	N= 678	N=494	N=618
Total energy (kcal)	2122 (26)	3024 (32)	1745 (25)	2357 (26)
Total fat (g)	82.0 (1.2)	74.5 (1.2)	68.8 (1.2)	58.3 (1.4)
Protein (g)	93.7 (1.6)	68.5 (0.9)	77.9 (1.4)	56.0 (0.8)
Carbohydrate (g)	250.1 (3.5)	463.7 (5.3)	208.2 (3.3)	394.2 (4.3)
Saturated fat (g)	21.0 (0.4)	18.4 (0.6)	16.4 (0.4)	13.2 (0.5)
Monounsaturated fat (g)	44.6 (0.7)	30.1 (0.8)	37.6 (0.7)	23.2 (0.6)
Polyunsaturated fat (g)*	17.3 (0.2)	17.0 (0.3)	15.4 (0.3)	14.6 (0.3)
Cholesterol (g)*	278.5 (6.9)	270.8 (7.7)	233.6 (8.0)	225.8 (8.1)
Percent calories from fat	34.8 (0.3)	21.7 (0.3)	35.2 (0.4)	21.7 (0.3)
Calcium (mg)	586 (12)	532 (12)	514 (14)	485 (12)
Phosphorus (mg)	1270 (19)	1427 (17)	1060 (19)	1163 (14)
vitamin A (IU)	8501 (221)	5057 (311)	8200 (222)	4153 (344)
b -carotene (IU)	5612 (176)	4333 (167)	5572 (173)	4000 (167)
Crude fiber (g)	4.3 (0.1)	4.9 (0.1)	4.0 (0.1)	4.6 (0.1)
vitamin c (mg)	117.6 (2.5)	70.3 (2.5)	114 (2.9)	65.5 (2.3)

*P value > 0.05 for North America - China comparison in both sexes

North American Chinese consumed more red meats, particularly beef, more dairy products and fruits, but less soybean products and vegetables than Chinese in China (Table 3). Higher consumption of meat and dairy products in North American Chinese contributed to their higher intakes of protein and fat.

Table 3. Mean (SE) times per week consumption of food groups among Chinese in North America and China.

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North America

	Men		Women
	North America	China	China
	N=698	N=678	N=494	N=618
Pork	5.8(0.2)	4.1 (0.2)	5.0(0.2)	3.4(0.2)
Beef	3.1 (0.1)	0.2 (0.0)	2.4 (0.1)	0.1 (0.0)
Red Meat	9.2 (0.2)	4.3 (0.2)	7.8 (0.2)	3.4 (0.2)
Dairy	8.7 (0.3)	0.8 (0.1)	6.7 (0.3)	0.5 (0.2)
Soy Products	1.5(0.1)	5.2 (0.2)	1.3 (0.1)	5.1 (0.2)
Vegetables	19.5 (0.4)	21.9(0.6)	18.7(0.5)	24.1 (0.7)
Fruits	12.2 (0.3)	3.3(0.2)	12.2(0.3)	4.1 (0.2)
Beer*	0.6 (0.1)	0.4 (0.1)	0.1 (0.0)	0.2 (0.0)
Wine	0.4 (0.1)	3.0(0.2)	0.1 (0.0)	0.7(0.1)
Liquor	1.1 (0.1)	2.1 (0.2)	0.2 (0.0)	0.4 (0.1)

>0.05 for North Chinese - China comparison in both sexes.

Chinese in China reported higher intakes of wine and hard liquor than Chinese in North America; while the intake of beer was similar in both continents. Regardless of gender, Chinese in China were more frequent consumers of alcoholic beverages than North American Chinese. The mean frequencies of alcoholic consumption (combined beer, wine and hard liquor) were 2.1 and 0.4 per week for North American Chinese men and women, respectively, and 5.5 and 1.3 for Chinese men and women in China, respectively.

Chinese in China reported spending more time in vigorous activities and walking, and less time in sitting than did Chinese in North America (Table 4). Average daily energy (kcal) expenditures were higher in China than in North America for both sexes.

Table 4. Mean (SE) daily physical activity of Chinese in North America and China.

China

	Men		Women
	North America	North America	China
	N=698	N=678	N=494	N=618
Energy (kcal) expenditure	2882 (25)	3218 (32)	2508 (26)	2707 (25)
Sitting (hours)	8.1(0.1)	6.0(0.1)	80(0.1)	5.7(0.1)
Vigorous activity (hours)	0.34(0.04)	2.69(0.12)	0.23(0.04)	1.20(0.09)
Moderate and light activity (hours)	7.2 (0.1)	6.5(0.l)	7.5(0.l)	8.2(0.1)
Sleeping (hours)	8.4 (0.1)	8.8(0.1)	8.3(0.1)	8.8(0.1)
Walking per day (miles)	4.7 (0.1)	6.4 (0.1)	4.5 (0.2)	9.2 (0.1)
Stairs climbed per day (flights)	7.0 (0.4)	--	6.0 (0.4)	--
Biking (Li)*	--	2.4 (0.2)	--	0.7 (0.1)

* 1 Li = 0.67 mile.

Discussion

Subjects in this study were selected randomly from the general population, and their nutrient intake, physical activity and body size represent those of middle-aged and elderly Chinese. Two previous studies^9,10 have assessed dietary intake of Chinese Americans; their sample sizes (n=346⁹, n=67¹⁰) were small compared to the present study (n=1192). These studies reported much lower daily intake of protein and fat (46.2 g fat⁹,75 g protein and 49 g fat¹⁰) than the present study (86 g protein, 75 g fat). The dietary assessment methods in this study (diet history^3a) compared with those used in the two earlier studies (24-hour recall^9,10) may explain some of the differences.

The present results suggest that the dietary habits of North American Chinese are more similar to those of North American whites than of Chinese in China. For example, the quartile distributions of intakes of total fat and total energy for North American Chinese in our study were similar to those reported for whites in Utah¹¹.

The main source of red meat in the Chinese diet was pork. However, North American Chinese consumed beef in much higher proportion than Chinese in China or in Singapore¹². Red meats and dairy products accounted for two-thirds of the saturated fat in the North American Chinese diet, whereas pork was the main source of saturated fats in China.

Chinese in China seldo 1000 m consumed dairy products, however, their calcium intake was similar to that of North American Chinese. Their calcium intake comes from higher consumption of soybean products and calcium-rich vegetables. Another notable difference between the diet of North American Chinese and Chinese in China was the higher consumption of fruits among North American Chinese. A lower intake of fruits among Chinese in China might contribute to their lower intake of vitamin C. A recent dietary survey of elderly Chinese in China showed that the urban elderly consumed more meat, dairy products and fruits than the rural elderly¹³. The percentage of calories from fat (30.7 %) in urban elderly was closer to that of Chinese Americans (35 %) than of Chinese in China (22 %) in our study. One can assume that with growing economic affluence in China, there is a tendency towards a more Western dietary intake.

Chinese in China reported higher consumption of alcoholic beverages (combined beer, wine and hard liquor) than Chinese in North America. However, they reported a lower consumption of alcohol compared with that of US males and females surveyed in the First National Health and Nutrition Examination Survey (NHANES I) conducted in 1974-75¹⁴. The average number of drinks per week of alcohol consumption (combined beer, wine and hard liquor) among Chinese men and women in China was 5.5 and 1.3, respectively, whereas that of American men and women was 7.3 and 2.1

respectively. Our findings agree with other studies^15,16 showing lower alcohol consumption in Chinese communities compared to western countries. In a study on acculturation and alcohol consumption among Chinese college students^l7, alcohol consumption was found to be related to the degree of assimilation into American society. No differences between alcohol consumption and acculturation level as measured by Chinese density (high or low) in census tract were found. Differences in results might be due to different measures of acculturation, and the age of the study population (college age vs middle age to old age). A study of drinking behaviours among three Asian American groups (Japanese, Chinese and Korean) yielded similar findings¹⁸, namely, a low prevalence of alcohol consumption and a gender difference in drinking behavior among Chinese Americans.

The differences in nutrient intakes between North American Chinese and Chinese in China were greater for men than women. The greater male differential may be explained in part by the longer duration of residence in the United States of Chinese men than of Chinese woman.

North American Chinese were less physically active and had greater BMI than were Chinese in China. Chinese in China consumed more kilocalories and had a higher energy expenditure. In both continents, estimates of energy consumption exceeded energy expenditure; this may be due to our overestimation of absolute rates of energy expenditure with various physical activity categories³.

However, Chinese immigrants to the US often go through a gradual and continuous process of incorporating a Western lifestyle, although not abandoning entirely their native health habits. Information on their lifestyle factors may be useful for planning culturally sensitive chronic disease prevention programs in the United States.

Acknowledgements - This research was supported by NIH grant CA-36503; by British Columbia Health Care Research Foundation; and by the National Academy of Sciences of the People's Republic of China. The authors are grateful to Anna Wu-Williams, Alice S. Whittemore, Zheng Shu, Richard Gallagher, Chong-Ze Teh, Zhoin Lun, Wang Xianghui, Chen Kung, Ling Chengde, Jiao Deng-Ao, Dexter Jung, Ralph S. Paffenbarger Jr, Rita Leung, Sophie Ledenla, Florence Lee, Lynn Fang, Annie Fung, Yasamin Deccio, Jill Obata and Christine Choy for their assistance.

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3a. Lee MM, Lee F, Ladenla SW, Miike R, Semiquantitative dietary history questionnaire for Chinese Americans. Ann Epidemiol (In Press).

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