点击显示 收起
1 From the Chinese Academy of Preventive Medicine, Beijing.
2 Presented at the symposium Fat Intake During Childhood, held in Houston, June 8–9, 1998. 3 Address correspondence to C Chunming, Chinese Academy of Preventive Medicine, 27 Nan Wei Road, Beijing 100050, China. E-mail: ccm{at}ccs.capm.ac.cn.
ABSTRACT
Although the fat intake of Chinese children is not critically high, on the basis of an 8-province survey, the fat intake of urban boys aged 12–15 y rose from 17% of their total energy intake in 1989 to nearly 30% in 1993. In contrast, a national survey conducted in 1992 indicated that the average fat intake of rural boys and girls aged 2–15 y was insufficient to meet the growth needs of early childhood, ranging from 16% to 20% of their total energy intake. The prevalence of underweight and stunting among Chinese children declined from 1990 to 1995, and there was a disparity between the number of those affected in urban areas compared with rural areas. In a 1991 dietary survey of Chinese boys <6 y, stunting appeared to be linked with a low intake of protein and fat. Data on schoolchildren aged 7–17 y showed an improvement in nutrition from 1991 to 1995, but the prevalence of a low weight to height ratio was markedly higher among urban 17-y-old girls. Overweight and obesity are increasing among urban children and are of particular concern at 11 and 12 y of age. Detailed studies should be conducted to analyze the major risk factors of overweight and obesity and to establish appropriate interventions.
Key Words: Fat intake • nutritional status • children • China
INTRODUCTION
The dietary fat intake of children plays an important role in child development, particularly with regard to underweight, stunting, overweight, and obesity. Data on dietary fat intake linked to individual child development are scarce in China. Obesity, underweight, and stunting are the outcomes of multiple contributing factors that play comprehensive roles; they cannot be attributed to any single factor. It is difficult to identify the role of dietary fat intake in child development without considering other nutritional factors as well as social and cultural factors.
TREND OF DIETARY FAT INTAKE OF CHILDREN
The 1992 National Nutrition Survey (1) involved a random sample of 25033 households, providing dietary data on 20905 children aged 2–15 y. In addition to the measurement of weight and collection of dietary records, individual food consumption data were collected by the children's caregivers on the basis of 24-h recall. The average fat intake of the children was 23–30% of total energy intake in the urban areas and 16–20% in rural areas (Table 1). Relative fat intake decreased with increased age. Among children living in rural areas, the fat intake was marginally low; among children aged 2 y, it was only 20% of total energy intake, whereas among 12–15-y-old children, fat intake dropped to as low as 16.4–17.5% of energy intake. The quality of the diet in rural areas needs improvement, especially among children <6 y of age.
View this table:
TABLE 1. Dietary fat intake of 20905 children in China (1992)1
Calculations indicate that the average energy intake of Chinese children aged 2–15 y met 100% of the recommended dietary allowance (RDA) in 1992 (1). The average protein intake was 90–103% of the RDA in urban areas and ranged from 83% to 95% of the RDA in rural areas, except for an abnormally low intake of 77.3% of the RDA for protein among 2-y-old girls. In general, the Chinese diet is low in calcium, riboflavin, vitamin A, and zinc. The iron intake is adequate, but its bioavailability is very low; the prevalence of anemia was 15–20% among children aged 2–15 y in 1992 (1).
In the China Health and Nutrition Survey, which has been conducted since 1989 in 8 provinces (ie, Hubei, Hunan, Guizhou, Guangxi, Jiangsu, Shandong, Henan, and Liaoning), data for 3500 boys aged 2–15 y are collected in both urban and rural areas (2). Data from 1989, 1991, and 1993 have been analyzed and dietary trends are shown in Table 2 and Table 3. There were differences between urban and rural boys' fat intake (Table 2) and fat intake as a percentage of energy generally declined with increasing age. However, the fat intake of both rural and urban boys increased dramatically, ie, by as much as 30–50%, over the 4-y time period. In 1991 there was a marked increase in fat intake, which was attributed to increased consumption of animal food and vegetable oil in those households. The total energy intake of boys aged 2–15 y was adequate, ranging from 91% to 117% of the RDA (Table 3).
View this table:
TABLE 2. Fat intake of 3500 boys, 1989–19931
View this table:
TABLE 3. Energy intake of 3500 boys, 1989–19931
NUTRITIONAL STATUS OF CHILDREN AND QUALITY OF DIET
The nutritional status of Chinese children showed an improvement from 1990 to 1995. Anthropometric data on children aged <6 y were collected in a nutrition surveillance program involving 5000 children in 1990 and involving 3000 children in 1995, and the 1992 National Child Survey collected similar data on 130000 children. Changes in the z scores of weight-for-age and height-for-age from 1990 to 1995 are shown in Table 4 and Table 5. The results show that the z scores of both rural and urban children had increased and the prevalence of a z score <-2 was reduced (3).
View this table:
TABLE 4. z Scores of height-for-age of children <6 y of age, 1990–19951
View this table:
TABLE 5. z Score of weight-for-age of children <6 y of age in China1
From 1990 to 1995 the prevalence of stunting among children aged <6 y decreased by 0.5 and 2.3 percentage points in urban and rural areas, respectively. The prevalence of stunting in rural areas was >4 times that in urban areas, as indicated in Table 4. During the same period, the prevalence of underweight among children <6 y of age decreased by 3.4 percentage points in urban areas and 4.8 percentage points in rural areas, with a marked disparity in the prevalence of underweight between urban and rural areas, as shown in Table 5. The prevalence of weight for height z scores >2 in rural children <6 y of age increased from 1.1% to 12.6% (Table 6). The weight-for-height z scores of rural and urban children in individual age groups, with the most striking changes occurring between ages <1 and 4 y, are shown in Table 7.
View this table:
TABLE 6. z Score of weight-for-height of children <6 y of age, 1990–19951
View this table:
TABLE 7. z Score of weight-for-height of children <6 y of age by age group, 1990 and 19951
The Nutrition and Health Survey information on the nutrient intake of 2–5-y-old stunted and normal boys in 8 provinces in 1991 (Table 8) is useful in identifying possible dietary factors contributing to stunting and provides an indication of the nutritional inadequacy of the stunted boys' diet. Because the number of height-for-age z scores <-2 was small, the differences between stunted and normal boys might not be statistically significant but may serve as a hint of the dietary factors potentially attributable to the deficit in the height growth of the preschoolers. Such differences underscore the importance of protein, fat, calcium, and riboflavin in the diet. Further study of the diet of children, including intake of fat and other nutrients, will be critical in making nutrition interventions for the correction of child malnutrition in China cost-effective.
View this table:
TABLE 8. Nutrient intake of stunted boys and normal boys in 19911
Data collected by the National Survey on Physical Fitness and Health of Chinese Students in 1991 and 1995 were compared by applying the weight-for-height value of the 80th percentile of normal students as the standard (4). As shown in Table 9, the percentage of urban students aged 7–17 y with weight-for-height <90% of the standard (ie, low weight-for-height) decreased, whereas the percentage of overweight (weight-for-height >110% of the standard) greatly increased. Although the percentage of low weight-for-height increased somewhat in the rural areas, the prevalence of low weight-for-height was generally no higher there than in the cities, particularly in 1991. It is noteworthy that during this period there was a great increase in the percentage of low weight-for-height among girls aged 17 y, from 49.6% to 57.9% in urban areas and from 35.8% to 46.5% in rural areas. Factors related to this phenomenon have yet to be defined.
View this table:
TABLE 9. Weight-for-height of students aged 7–17 y, 1991 and 19951
OBESITY
The fact that the percentage of overweight students in urban areas peaked in 1995 at the age of 12 y and decreased at the age of 17 y, particularly in girls, is illustrated in Table 9. Because of the lack of information on the social, cultural, and economic factors underlying this problem in China, only 2 small-scale studies in schools are described here. First, a case-control study of 133 obese students aged 8–13 y in Jinzhou city in northeast China indicated that the major risk factors of obesity among the boys were overeating [relative risk ratio (RR) = 8.14], a preference for fatty food (RR = 2.72), and a high body mass index of the mother (RR = 1.29). For obese girls, the major risk factors of obesity were frequent feelings of hunger (RR = 5.07) and obesity of the mother during pregnancy (RR = 1.23) (5).
Second, a study of 1721 students aged 6–12 y in 3 primary schools in Beijing in 1993 showed that the prevalence of obesity had risen to 17.2%, a sharp increase from the 10.9% recorded only 3 y earlier (6). The prevalence of obesity among the boys was 20.1%; in the girls, 14.9%. The peak occurred at 11 y of age, when the prevalence of obesity was 39.4% in boys and 36% in girls. The major risk factors of obesity were frequent snacks (odds ratio = 2.65), eating quickly or finishing a meal in 15 min (odds ratio = 2.51), unbalanced dietary habits (odds ratio = 1.84), having an obese mother or father (odds ratio = 1.73), and birth weight >3.5 kg (odds ratio = 1.52). Other risk factors of obesity included a preference for meat or eggs, a dislike of vegetables and fruit, and nonparticipation in physical exercise .
Obesity is rapidly increasing among children in urban China. Additional, detailed studies should be conducted to identify the major risk factors of obesity so that appropriate interventions can be focused on preventing or slowing any further increase.
ACKNOWLEDGMENTS
I acknowledge Zhai Fengyin, Ma Linmao, Lu Bin, and He Yuna for their assistance in the data analysis.
REFERENCES