1000

Asia Pacific J Clin Nutr (1997) 6(4): 277-286

Changes in food, nutrient and energy intake in People’s Republic of China samples of urban and rural north and south adults surveyed in 1983-84 and resurveyed in 1987-88

BH Dennis¹, B Zhou², X Liu³, J Yang², J Mai³, T Cao², G Ni³, L Zhao² and J Stamler⁴ for the PRC-USA Research Group*

¹ University of North Carolina, Chapel Hill, North Carolina, USA
² Cardiovascular Institute and Fu Wai Hospital, Beijing, PRC
³ Guangdong Provincial Cardiovascular Institute, Guangzhou, PRC
⁴ Northwestern University Medical School, Chicago, Illinois, USA

*PRC-Beijing: Shouchi Tao, Rusheng Tsai, Xigui Wu, Beifan Zhou, Hongye Zhang, Yangfeng Wu, Ying Li
PRC-Guangzhou: Zhendong Huang, Yihe Li, Susu Rao, Runchao Cen, Qiling Zhuo, Xiaoqing Liu
USA: Paul S Bachorik, Maryland; A Sonia Buist, Oregon; CE Davis, North Carolina; Barbara H Dennis, North Carolina, Aaron R Folsom, Minnesota; Jeremiah Stamler, Illinois; James D Taylor, Massachusetts (81-88); G Russell Warnik, Washington (81-90); O Dale Williams, Alabama
USA-NHLBI: Claude Lenfant, Suzanne Hurd, William Friedwald (83-88), Laura Greene (deceased), Ruth Hegyeli

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Dietary patterns were assessed in a prospective study of cardiovascular disease (CVD) risk factors in four Chinese populations: Beijing urban (BJ-U) and rural (BJ-R), Guangzhou urban (GZ-U) and rural (GZ-R). A total of 10,076 men and women 35-54 years old were surveyed in 1983-84 and resurveyed in 1987-88. Dietary data were obtained in a subsample of about 10% (n=169 BJ-U, 178 BJ-R, 198 GZ-U, 230 GZ-R). Three 24-hr recalls were collected on each participant in each survey. Comparison of mean intakes in the two periods showed increases in meat, poultry, fish (except GZ-R), eggs (rural only), milk (except BJ-R) and alcoholic beverages. The largest shifts were in meat intake (29%-39%), alcoholic beverages (71%-104%) and fats in the urban samples (33%-35%). These changes are reflected in increased mean intakes of animal protein, fat, saturated fatty acids (SFA) and higher Keys scores. Mean total fat intake now exceeds the PRC recommended range of 20-25% of energy in three of the four samples.

During this period BMI increased in all samples especially among men (3% - 6%). These surveys, conducted during a period of rapid economic development in China, show that such changes promote shifts in dietary patterns and energy balance towards increased risk of cardiovascular disease.

Key words: dietary survey, China, nutrient intake, cardiovascular

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Introduction

Coronary heart disease (CHD) is uncommon in the People’s Republic of China (PRC). Its r 1000 elatively rare occurrence has been attributed to particularly low serum total cholesterol related in turn to low saturated fatty acids (SFA) and cholesterol in the traditional Chinese diet. Economic reforms implemented in the early 1980s have significantly increased income levels in many segments of the Chinese population. It is a reasonable hypothesis that these changes, coupled with increased access to Western products are having an impact on the traditional diet and other lifestyle characteristics known to influence population serum lipids and other major cardiovascular risk factors, including blood pressure.

The Peoples Republic of China-United States (PRC-USA) Collaborative Study of Cardiovascular and Cardio-pulmonary Epidemiology initiated in 1981 under the PRC-USA Governmental Cooperation in Science and Technology provides an opportunity to test the foregoing hypothesis about dietary trends during this period of rapid economic change in four areas of China. This joint research study has carried out three surveys -- 1983-84, 1987-88, and 1993-94 -- on eight cohorts of adult men and women identified from urban and rural populations in, or close to, Beijing in the north and Guangzhou in the south of China. At each survey, three 24-hour dietary recalls were done on each of 775 men and women ages 35-54 years at baseline in 1983-84. Nutrient analyses have been completed from surveys 1 and 2. This report gives changes in food and nutrient intake from 1983-84 to 1987-88 -- by sex, site (north, south), and setting (urban, rural) -- related to the foregoing general hypothesis and its specific aspects.

Subjects and methods

Study populations: Four cohorts of at least 2000 men and women 35 to 54 years old were selected for the study. The Beijing population included workers from the Capital Iron and Steel Complex (CISC) in Beijing. This large complex encompassed 16 separate factories employing about 80,000 people at the time screening was initiated in 1981. All age-eligible workers in five factories were asked to participate. Due to the small number of female workers at CISC, additional women in a specified residential district, most of them wives of CISC workers, as well as women working in other nearby factories were also surveyed. The Beijing rural population included all age-eligible men in all 11 farm brigades and all age-eligible women in 9 of 11 farm brigades in Shijingshan agricultural district at the time of the 1981 census. The Guangzhou urban population comprised mainly employed male and female manual workers, plus some engineers, technicians, cadres (party members), physicians, and retired workers from the Guangzhou Ship-yard Company. The request to participate was made to age-eligible persons in eight of the 25 company workshops. The Guangzhou rural population comprised age-eligible men and women working in 14 of 21 agricultural villages near Guangzhou, in the Dashi township of Panyu County at the time of the 1981 census. Approximately 10% of those screened were invited to participate in a more intensive data collection, which included assessment of dietary intake and urinary electrolytes. In Beijing, the urban subsample was selected on a day when employees of a given factory appeared for the general examination. From the first 50 general examinees, 20 were selected and studied for three consecutive days; additional 20/50 samples were sequentially selected. The rural subsample was selected in a similar way. These were "convenience" subsamples, since potential participants were excluded if they 1) lived far away, 2) worked outside the village or industrial complex, 3) appeared unreliable, or 4) were unavailable for three consecutive days of data collection.

In Guangzhou, a 10% subsample was rand 1000 omly selected from attendees at the general survey. Every 10th person was included, unless the person refused or was judged to be potentially unreliable, in which case the 11th person was selected.

Data in this report are based on the cohorts of participants who provided at least two reliable dietary recalls both in the fall of 1983-84 and again in the fall of 1987-88. Sample sizes for participants who completed both surveys were 169 (Beijing urban), 178 (Beijing rural), 198 (Guangzhou urban), and 230 (Guangzhou rural). Three individuals were excluded from the baseline analysis because they did not return for subsequent surveys.

Dietary assessment: Dietary data were collected according to a standardised 24-hour dietary recall procedure over three consecutive days. The dietary assessment was carried out by physicians trained according to a common protocol. Standard utensils such as bowls and spoons, samples of real food, scales, and graduated cylinders were used to quantify amounts of foods reported. For the Guangzhou rural area, dietary interviews were usually conducted in the home. Otherwise, participants were interviewed at screening sites. Quality control procedures for the interview and data processing consisted of standardised training, standard procedure manuals, and random observation and inspection of forms by supervisors.

Nutrient database: Energy and nutrient intakes were calculated from a specially constructed nutrient database, which is a subset of the Chinese national tables of food composition¹, supplemented by international data, chemical assays, and calculated recipes. When published nutrient composition data were unavailable, nutrients were imputed according to standard procedures². Many fatty acid values and most carbohydrate fractions were imputed.

Nutrients in the database were selected for their putative role in cardiovascular risk factor development and include total fat, saturated (SFA), monounsaturated (MFA), and polyunsaturated (PFA) fatty acids, cholesterol, protein (total, animal, vegetable), total carbohydrate, starch, refined sugar, alcohol, sodium, potassium, and calcium.

Composition of foods in the database is generally based on the state of the food when purchased. Hence, composition of commodity foods (eg, meats and vegetables), is for raw foods, and for processed foods (such as commercial biscuits), it is for the cooked product. Recipe items were usually calculated from raw ingredients. No factors were applied to account for alterations in nutrients during cooking. Leaching of sodium and potassium into the cooking medium was not considered to be a major source of error since most meats and vegetables were prepared either stir-fried or as soups and the cooking medium was consumed.

Development of the nutrient database was a collaborative project involving Chinese investigators; the National Heart, Lung, and Blood Institute; the U.S. Department of Agriculture; and the University of Minnesota Nutrition Coordinating Center (NCC). Before utilising the nutrient database for calculation of recalls, it was subjected to a series of logic and consistency checks. Unusual values were flagged and verified or corrected. The nutrient database is maintained in the United States at the NCC and in China at Fu Wai Hospital in Beijing and at Guangdong Provincial Cardiovascular Institute in Guangzhou. Data in this report are based on version 1 of the nutrient database².

Body size and energy expenditure: Height was measured to the nearest centimetr 1000 e (cm) with use of a standard right-angle device. Each participant was measured without shoes and in a standing position. Weight was measured to the nearest kilogram (kg) with use of a spring balance. Each participant was measured wearing usual indoor clothing and no shoes.

Body mass index (BMI) was calculated as: weight (kg)/ height (m)². Energy expenditure was calculated as kilo-calories per kg body weight.

Statistical methods: To assess changes in reported nutrient and food intake, means, and standard deviations are reported for each of the two surveys and differences between them calculated.

Results

Changes in food intake

Food is a complex mixture of nutrients and other compounds, the balance of which can have beneficial or detrimental effects on serum lipids and blood pressure. Changes in food intake from 1983-84 to 1987-88 by location and site are displayed in Figures 1-5, and for men and women separately in Tables 1-4.

Figure 1. Mean consumption of meat, fish, and poultry in 1983-84 survey and 1987-88 re-survey in Beijing and Guangzhou.

Figure 2. Mean consumption of eggs, milk and added fats in 1983-84 survey and 1987-88 re-survey in Beijing and Guangzhou.

Figure 3. Mean consumption of staple foods and fresh vegetables in 1983-84 survey and 1987-88 re-survey in Beijing and Guangzhou.

Meat consumption rose in all four areas but the increase was greater in the GZ rural sample where it rose 39%. By 1987-88, reported mean consumption of meat ranged from 63 g/d in BJ rural to 105 g/d in GZ urban samples. The increase in meat consumption was similar in men and women in Beijing and urban Guangzhou. The most striking increase occurred in Guangzhou rural men where meat consumption nearly doubled. By 1987-88, meat contributed on average 13% of energy, an increase of 4%.

Figure 4. Mean consumption of legumes and fruits in 1983-84 survey and 1987-88 re-survey in Beijing and Guangzhou.

Figure 5. Mean consumption of salted products and alcoholic beverages in 1983-84 survey and 1987-88 re-survey in Beijing and Guangzhou.

Fish consumption decreased slightly in GZ rural samples and increased in GZ urban women and Beijing urban and rural samples. Fish consumption was considerably lower in Beijing, averaging about 10 g/d compared to nearly 60 g/d in Guangzhou in 1987-88. There were modest changes in fish and poultry consumption. Poultry was rarely consumed in Beijing. In Guangzhou mean consumption more than doubled in the urban sample and the increase was even larger in the rural sample. Changes were similar in men and women.

Egg consumption decreased slightly in both urban samples. Rural women had a larger increase than men. Mean egg consumption was much lower in the GZ rural sample, 11 g/d vs 25 g/d in the other samples. There was a small increase in milk consumption (except GZ rural); however the mean was still very low, ranging from 3 g/d in GZ rural men to 33 g/d in BJ urban women.

Overall 1000 total consumption of animal products increased by 25 to 30% except in the Guangzhou urban sample where it increased only 13%. In 1987-88 consumption of animal products ranged from 116 g/d in BJ rural sample to 219 g/d in GZ urban sample. On average animal products contributed 18% of energy in 1987-88.

Table 1. Mean grams of food and percent of energy for Beijing urban men and women surveyed in 1983-84 (V1) and re-surveyed in 1987-88 (V2).

Foods	V1			V2			V2-V1			V1			V2		V2-V1
	Mean g	SD	Mean % en	Mean g	SD	Mean % en	g/d	%	Mean g	SD	Mean % en	Mean g	SD	Mean % en	g/d	%
	Men (n = 75)								Women (n = 94)
Meat	90	74.4	14.2	124	96.6	17.7	34	38	52	43.6	11.7	64	51.7	14.8	12	23
Poultry	1	6.4	0.1	2	7.2	0.1	1	100	--2	--	--	1	3.2	0.1	--	--
Fish	10	26.0	0.4	14	29.7	0.5	4	40	8	20.3	0.5	8	14.9	0.5	0	0
Eggs	30	32.0	1.7	28	33.6	1.6	-2	-7	27	26.6	2.3	23	26.3	1.9	-4	-15
Milk	22	58.1	0.6	25	68.1	0.7	3	14	19	56.4	0.7	33	80.3	1.2	14	74
Fats	29	16.8	9.0	37	22.7	11.1	8	28	18	9.9	7.9	25	16.6	11.1	7	39
Staples	508	113.3	53.0	481	126.1	50.8	-27	5	400	106.0	60.7	367	98.7	1000 56.0	-33	8
Legumes	61	78.9	3.0	69	80.9	3.2	8	13	32	60.4	2.3	28	59.1	2.1	-4	-12.5
Fresh Veg	288	126.7	2.7	284	131.1	2.7	-4	-1	271	160.2	3.5	266	154.9	3.3	-5	-2
Fruits	58	63.9	1.0	86	106.2	1.6	28	48	74	82.2	1.8	88	97.4	2.1	14	19
Nuts	11	23.0	1.9	13	24.5	2.4	2	18	3	11.2	0.8	4	10.2	1.0	1	33
Salted Veg1	29	14.9	0.8	33	16.1	0.7	4	14	20	10.4	0.7	17	9.5	0.5	3	15
Dried Veg	4	11.5	0.3	4	7.7	<0.1	0	0	1	2.9	0.1	3	7.9	0.1	2	200
Sweets	55	57.1	8.2	23	35.3	3.0	-32	-58	32	34.1	7.1	26	30.8	5.0	-6	-19
Alcoholic Bev	47	90.8	3.2	95	214.8	4.0	48	102	2	16.0	0.1	1	6.3	0.2	-1	-50

¹includes salt and soya sauce; ²negligible

Table 2. Mean grams of food and percent of energy for Beijing rural men and women surveyed in 1983-84 (V1) and re-surveyed in 1987-88 (V2).

Foods

V1

V2

V2-V1

V1

V2

V2-V1 1000

Mean g

SD

Mean % en

Mean g

SD

Mean % en

g/d

%

Mean g

SD

Mean % en

Mean g

SD

Mean % en

g/d

%

	Men (n = 107)								Women (n = 76)
Meat	55	64.1	8.9	74	68.9	12.2	19	35	44	42.1	9.3	56	57.9	12.8	12	27
Poultry	--	--	--1	2	5.6	0.1	--	+	1	3.5	--	3	11.5	0.2	2	100
Fish	8	33.8	0.3	10	29.0	0.4	2	25	7	22.3	9	8	24.6	0.5	1	14
Eggs	20	25.2	1.0	20	36.2	1.1	0	0	17	22.2	1.3	21	25.4	1.7	4	23
Milk	21	83.7	0.7	27	87.6	0.7	6	29	7	37.7	0.2	19	59.5	0.7	12	171
Fats	23	15.0	6.3	26	16.1	7.7	3	13	17	12.6	6.5	21	12.6	8.7	4	24
Staples	667	226.7	63.8	552	184.0	57.9	-115	-17	552	184.0	57.9	419	148.6	59.9	133	24
Legumes	46	71.9	2.1	19	41.2	0.9	-27	-59	28	50.4	1.8	17	42.3	1.1	11	39
Fresh Veg	299	147.3	3.1	295	148.7	2.8	-4	-1	283	157.0	3.1	275	138.4	3.6	-8	-3
Fruits	94	96.7	1.6	70	113.2	1.3	-24	-26	118	128.6	2.7	119	126.2	3.0	1	1
Nuts	10	24.4	1.7	15	43.8	2.4	5	50	3	9.8	0.8	6	18.4	1.6	3	100
Salted Veg2	46	25.6	1.0	36	17.9	0.8	10	22	32	18.7	1.0	24	12.8	0.8	8	25
Dried Veg	--	--	--	3	4.9	0.1	--	--	2	4.3	--	2	4.7	--	0	0
Sweets	39	67.6	5.2	50	71.9	5.3	11	28	35	49.6	6.4	32	54.6	4.6	-3	-9
Alcoholic Bev	71	198.3	4.2	111	199.0