Since the introduction of a market economy in China in the early 1980s, many areas have moved from a situation of food scarcity to wide choice in diet in less than a generation. But the changes have been unevenly distributed. While the increase in the number of overweight adults in certain cities between 1982 and 1991 has been described as among the most rapid ever documented, rates of underweight adults in urban and rural areas fell by just 1% over the same period.

There is growing evidence that the long term consumption of an excess of nutrients and obesity in childhood has a strong association with hypertension, diabetes and heart disease in adult life. A study was carried out by the Centre for International Child Health in London and Zhejiang University to determine the impact of the current disparities in socio-economic status in urban and rural China on the nutritional status of adolescents.

The two study areas were Hangzhou, the capital of Zhejiang Province, one of the richest cities in China, and Chunan, a poor mountainous area in Zhejiang. Middle school enrolment is 99% and 96% in the two areas respectively. Twelve middle schools (predominant age range 13-16 years) were selected to be representative of the schools in the two areas. 

A total of 4 835 students completed a questionnaire which included questions about socio-demographic indicators, lifestyle, exercise and diet, together with anthropometry (measurement of the human body) and haemoglobin measurements.

The researchers found that:

• 3.6% of those questioned were overweight. Boys were twice as likely to be overweight and urban dwellers were ten times as likely.  More sedentary lifestyles, and specifically frequent playing of computer games (which were especially popular among urban boys), were associated with being overweight
• more adolescents were underweight (18%), with no urban-rural difference. Being underweight was more common in boys from poorer households
• anaemia (haemoglobin <120g/L) was present in 51% of girls and 21% of boys, with no urban-rural difference and no difference between menstruating and non-menstruating girls. Nearly three-quarters (72%) of those classified anaemic were only mildly so (haemoglobins between 110g/L and 120g/L)
• in the rural area diet was less varied, but there was also less convenience and snack food (high fat and salt content) consumed and students exercised more
• one third of the adolescents consumed dietary supplements on a regular basis. These included vitamins, iron, tonics and herbs, reputed in local culture to enhance health, increase energy and improve mental development.

The researchers' results suggest that:

• in wealthier urban China a dual picture is emerging with the problems of excess (overweight and obesity) co-existing with underweight and anaemia
• although rates of overweight adolescents are low in comparison with developed countries, the rapid emergence of this problem in a country where obesity was very rare before the mid-1980s is of concern and therefore the situation should be monitored
• in rural areas the problems of relative nutritional deprivation predominate,  but the health consequences of the underweight and borderline anaemia are unknown. The Chinese have become taller and leaner over recent decades. Longitudinal studies in these populations are necessary to establish appropriate cut-off points for when under nutrition becomes a serious risk.

Source(s):
'Disparities in economic development in eastern China: impact on nutritional status of adolescents', Public Health Nutrition 5(2): 313-318, by T. Hesketh et al, 2002

id21 Research Highlight: 25 September 2003

Further Information:
Therese Hesketh
Centre for International Child Health
Institute of Child Health
30 Guilford St
London WCI N1EH
UK

Contact the contributor: hesketh@mail.hz.zj.cn

Institute of Child Health, University of London

Other related links:
'Danger in disguise - spotting the warning signs of severe childhood illnesses'

'Caught in a dilemma: mother to child HIV transmission in Zambia'

'Breast practice? Preventing HIV transmission through breast feeding'

'Fighting fits: childhood malaria and seizures in sub-Saharan Africa'

'Out of order: does the sequence of childhood vaccinations matter?'

See id21's collection of links relevant to maternal and child health.

See id21's collection of links relevant to NCDs and disability.