Fengying Zhai

Cohort Profile: The China Health and Nutrition Survey—monitoring and understanding socio-economic and health change in China, 1989–2011

This research journal article presents a detailed overview of a cohort profile of the China Health and Nutrition Survey (CHNS) which allows for the monitoring and understanding of socio-economic and health change in China from 1989-2011. The author discusses the history and development of the CHNS as a result of the countrys transformations since Chinas reform and open policy. The CHNS was established with the goal to develop a multipurpose longitudinal survey that would allow the research group to examine a series of economic sociological demographic and health questions. The article describes the design of the survey to include in-depth coverage at the individual household and community levels though it was not designed to be representative of China but to be randomly selected and capture a range of economic and demographic circumstances. It provides data randomly from eight different provinces and rounds have been completed nearly every three years since 1989. Though they are very complex to determine with the survey response rates and attrition are assessed along with descriptions of changes in lost-to-follow-up rates. The article describes key finds and publications to be numerous including links to obesity from occupation and transportation; nutrition and chronic disease; and important policy results for agriculture and poverty reduction programs. Lastly the author provides a summary of the CHNSs strengths and weaknesses and recommendations for accessing the data and further information.

A new stage of the nutrition transition in China

OBJECTIVE To fully explore the long-term shifts in the nutrition transition and the full implications of these changes in the Chinese diet. DESIGN A descriptive, population-based study. SETTING Data come from nationally representative surveys: the China Health and Nutrition Survey (1989-1997), the China National Nutrition Survey (1982 and 1992), the annual household consumption surveys of the State Statistical Bureau, and the Annual Death Report of China. RESULTS During the first part of the major economic transformation in China (before 1985), cereal intake increased but decreased thereafter. There was also a long-term reduction of vegetable consumption that has now stabilised. Intake of animal foods increased slowly before 1979 and more quickly after the economic reforms occurred. While the total energy intake of residents has decreased, as has energy expenditure, large changes in the composition of energy have occurred. The overall proportion of energy from fat increased quickly, reaching an overall average of 27.3% and 32.8% for urban residents in 1997. Over a third of all Chinese adults and 60.1% of those in urban areas consumed over 30% of their energy from fat in 1997. Large shifts towards increased inactivity at work and leisure occurred. These changes are linked with rapid increases of overweight, obesity and diet-related non-communicable diseases (DR-NCDs) as well as total mortality for urban residents. CONCLUSIONS The long-term trend is a shift towards a high-fat, high-energy-density and low-fibre diet. The Chinese have entered a new stage of the nutrition transition.

Prospective study on nutrition transition in China.

The aim of the prospective study reported here was to examine the effects of social and economic transformation on dietary patterns and nutritional status in China. The study began in 1989 and continued with follow-ups in 1991, 1993, 1997, 2000, and 2004. A total of 5000 subjects aged 18-45 years from 4280 households in nine provinces were included. Weighed records and three consecutive 24-h recalls were used. Over the study period, average consumption of all animal foods except milk increased, while cereal intake decreased. The proportion of animal protein and fat as a percentage of energy also increased. However, vitamin A and calcium intake did not increase and remained low. Child height and weight increased while undernutrition decreased and overweight increased. The results indicate that rapid changes in dietary pattern are associated with economic reforms in China.

Structural change in the impact of income on food consumption in China, 1989-1993.

China is undergoing a marked transition in its diet and nutritional status patterns. This study determines the structural change in the impact of income on food consumption in China during 1989-93. Utilizing data from a longitudinal study of 3800 households in China evidence points to a shift in the relationship between income dietary structure and total nutrient intake at the macrolevel. Overall it is noted that the increase in income over time in the country coincided with a shift in the demand for inferior and normal food groups. In addition there was a pronounced increase in the income elasticity for more luxury foods during the specified period while less superior goods became more inferior over this 4-year span. Such an increase in income elasticities for total energy and for energy from fat suggest a worsening of the composition of the diet in ways that are linked to obesity and obesity-related diseases as incomes continue to rise. In view of this several implications for the formulation of future nutrition policies in China are cited.

Dynamics of the Chinese diet and the role of urbanicity, 1991-2011.

Chinas food consumption patterns and eating and cooking behaviours changed dramatically between 1991 and 2011. Macronutrient composition has shifted towards fats, and protein and sodium intakes remain high and potassium intake low. The rapid decline in intake of coarse grains and, later, of refined grains and increases in intake of edible oils and animal‐source foods accompanied by major eating and cooking behaviour shifts are leading to what might be characterized as an unhealthy Western type of diet, often based on traditional recipes with major additions and changes. The most popular animal‐source food is pork, and consumption of poultry and eggs is increasing. The changes in cooking and eating styles include a decrease in the proportion of food steamed, baked, or boiled, and an increase in snacking and eating away from home. Prior to the last decade, there was essentially no snacking in China except for hot water or green tea. Most recently, the intake of foods high in added sugar has increased. The dietary shifts are affected greatly by the countrys urbanization. The future, as exemplified by the diet of the three mega cities, promises major growth in consumption of processed foods and beverages.

The China Health and Nutrition Survey, 1989–2011

The China Health and Nutrition Survey (CHNS) began in 1989 with the goal of creating a multilevel method of data collection from individuals and households and their communities to understand how the wide‐ranging social and economic changes in China affect a wide array of nutrition and health‐related outcomes. Initiated with a partial sample in 1989, the full survey runs from 1991 to 2011, and this issue documents the CHNS history. The CHNS cohort includes new household formation and replacement communities and households; all household members are studied. Furthermore, in‐depth community data are collected. The sample began with eight provinces and added a ninth, Heilongjiang, in 1997 and three autonomous cities, Beijing, Shanghai, and Chongqing, in 2011. The in‐depth community contextual measures have allowed us to create a unique measure of urbanicity that captures major dimensions of modernization across all 288 communities currently in the CHNS sample. The standardized, validated urbanicity measure captures the changes in 12 dimensions: population density; economic activity; traditional markets; modern markets; transportation infrastructure; sanitation; communications; housing; education; diversity; health infrastructure; and social services. Each is based on numerous measures applicable to each dimension. They are used jointly and separately in hundreds of studies.

Trends in the distribution of body mass index among Chinese adults, aged 20-45 years (1989-2000)

Objective:To describe body mass index (BMI, in kg/m2) distribution patterns and trends among Chinese adults, aged 20–45 years (1989–2000).Design:A descriptive, population-based study of BMI change.Setting:Chinese provinces (eight in 1989 and 1997; nine in 2000), representative of the household-based surveys (the China Health and Nutrition Survey, 1989–2000) using multistage, random cluster sampling, supplemented with annual household consumption survey data of the State Statistical Bureau (SSB).Subjects:A total of 4527, 4507 and 4046 adults, aged 20–45 years, in 1989, 1997 and 2000, respectively.Measurements:BMI (underweight: BMI<18.5 kg/m2 and overweight: BMI⩾25 kg/m2). Percentile curves for BMI in 1989 and 2000 were constructed by gender and age using the LMS (lambda, mu, sigma) method.Results:Compared with 1989, the 2000 BMI distribution curves flattened at higher levels of BMI (men and women). There was a 13.7% increase in the proportion of men and a 7.9% increase of women who were overweight or obese with a resulting greater change in the annualized prevalence rate for men. This increase in the prevalence of overweight and obesity was far greater than the decrease (2.1% for men; 2.2% for women) in that of underweight. Age–gender-specific percentile curves showed BMI increases mainly among women, aged 35–45 years, and among men at all age groups.Conclusions:Chinese BMI dynamics show much greater rates of change among men, aged 20–45 years, than among women, with the increase among women concentrated between ages 35 and 45 years. These changes portend large shifts in other diet-related non-communicable diseases in China over the following decades. Controlling the increasing trends of BMI, especially in men, is an important public health problem facing China.

Body weight patterns among the Chinese: results from the 1989 and 1991 China Health and Nutrition Surveys.

OBJECTIVES A longitudinal survey assessed the distribution of adult body weight among the Chinese population. METHODS Data from the 1989 and 1991 China Health and Nutrition Survey were used to study changes in the proportions of adults aged 20-45 years who were classified as underweight, normal weight, overweight, and severely overweight. RESULTS There was a slight decline in the proportion of men and women classified as underweight, but among lower-income persons an increase occurred. The proportion of adults with normal body weight decreased, and the proportions of those classified as overweight and severely overweight increased during the same period. The observed increases in proportions of adults classified as overweight and severely overweight were largely confined to the urban residents and to those in the middle- and high-income groups. CONCLUSIONS Results indicate increases in both obesity and undernutrition. Current efforts in China to develop a preventive health care policy emphasize the prevention of excess nutrient intakes and overnutrition and, hence, address the problem of the increase in obesity among well-to-do, mostly urban residents. However, the increase in undernutrition among low-income Chinese adults should not be overlooked and requires further research and serious policy consideration.

Longitudinal relationships between occupational and domestic physical activity patterns and body weight in China

Objectives:To examine the longitudinal relationship between occupational and domestic sources of physical activity and body weight in a sample of Chinese adults.Methods:Population-based longitudinal observational study of Chinese adults (4697 women and 4708 men) aged 18–55 from the 1991, 1993, 1997, and 2000 waves of the China Health and Nutrition Survey. Measured height and weight and detailed self-reported energy expenditure from multiple occupational and domestic sources were assessed over a 9-year period. Longitudinal relationships were modeled using linear random effects models.Results:Increased occupational physical activity resulted in overall lower body weight for both men and women (β-coefficients (95% confidence interval (CI)) for high levels: −0.46 (−0.76, −0.15) for men, −0.36 (−0.62, −0.10) for women, and increased domestic physical activity resulted in overall lower body weight in men (β-coefficient (95% CI): −0.40 (−0.62, −0.18)).Conclusions:Physical activity that occurs in the occupational and domestic sectors is often overlooked; yet our research suggests they have important effects on body weight in Chinese adults. As China continues to urbanize, energy expenditure from these sources is decreasing, and our results point out the need to explore these types of physical activity more broadly across the world as potential sources of weight gain.

Dynamic shifts in Chinese eating behaviors.

The purpose of the study is to examine the dynamic eating behaviors of the Chinese people, focusing on snacking and the choice of cooking methods, and to identify the influences of socioeconomic factors on these eating behaviors. Data for this study were from the China Health and Nutrition Survey (CHNS). There were 11780 subjects, older than two years (y), from the 1991 and 11169 from the 2004 surveys respectively. Logistic regressions of pooled data were performed to evaluate how socioeconomic status (SES) was associated with two eating behaviors: snacking and consuming excessive amounts of fried foods. Simulation techniques were used to clarify the effects of the results that included significant interaction terms. Results showed that the rapid shift in the food and nutrient profile of the Chinese population is accompanied by equally profound changes in meal and cooking patterns. Snacking behavior is beginning to emerge and there are shifts away from the steaming and boiling of food to the, less healthy, frying of food. Income is positively associated with the consumption of both snacks and excessive fried food. Urban residents are also more likely to snack and to consume excessive amounts of fried foods than rural residents. These findings indicate that eating behaviors are beginning to change rapidly toward less healthy options in China. SES plays a vital role in the early stages of the eating behavior transition in China. Future health promotion programs targeting the higher-SES population will exert far-reaching effects on the improvement of health status in this group.