China Health and Nutrition Survey - Health and Nutrition Survey

Health and Nutrition Survey

All household members in 1991 and subsequent surveys provided individual data on dietary intake, body composition, blood pressure, health history, and health-related behaviors (e.g., smoking, beverage consumption, medication, key chronic diseases). These data include dietary intake for 3 consecutive days as well as detailed physical examinations that include blood pressure (for adults), clinical measures of health, weight, height, and arm and head circumference (and also waist-hip ratios beginning in 1993). The 3 consecutive days during which detailed household food consumption data were collected were randomly allocated from Monday to Sunday and are almost equally balanced across the 7 days of the week for each sampling unit. Household food consumption was determined by examining changes in inventory from the beginning to the end of each day, in combination with a weighing and measurement technique. Chinese balances with a maximum limit of 15 kilograms and a minimum of 20 grams were used. All processed foods (including edible oils and salt) remaining after the last meal before initiation of the survey were weighed and recorded. All purchases, home production, and processed snack foods were recorded. Whenever foods were brought into the household unit, they were weighed and preparation waste (e.g., spoiled rice, discarded cooked meals fed to pets or animals) was estimated when weighing was not possible. At the end of the survey, all remaining foods were again weighed and recorded. The number of household members and visitors were recorded at each meal.

Individual dietary intake for the same three consecutive days was surveyed for all children aged 1 to 6 and all adults aged 20 to 45 in 1989, and for all individuals in later years. This was achieved by asking individuals each day to report all food consumed away from home on a 24-hour recall basis, and the same daily interview was used to collect at-home individual consumption. In a few cases, subjects missed one day due to absence, but over 99 percent of the sample was available for the full three days of data.

The collection of both household and individual dietary intake allowed us to check the quality of data collection by comparing the two. Thus, each individual's average daily dietary intake, calculated from the household survey, was compared with his or her dietary intake based on 24-hour recall data. Where significant discrepancies were found, the household and the individual in question were revisited and asked about their food consumption in order to resolve these discrepancies.

All field workers were trained nutritionists who are otherwise professionally engaged in nutrition work in their own counties and who have participated in other national surveys. Almost all interviewers were graduates of post-secondary schools; many had four-year degrees. In addition, 3 days of specific training in the collection of dietary data were provided for this survey.

The 1991 Food Composition Table (FCT) for China was utilized to calculate nutrient values for the dietary data of 2000 and previous years. This FCT represents a significant advance over the earlier China FCT both for higher quality chemical analyses and for improved techniques of developing average nutrient values for foods whose nutrient value varies over the country in a geographic context. The UNC group has worked with the National Institute of Nutrition and Food Safety to update and improve this FCT. A new version of FCT (2002) was used for 2004 survey and the latest version (2004) was used for 2006 survey.