Zinc intake and dietary pattern in Jiangsu Province, China: consequences of nutrition transition

Y. Qin

Research output: Thesisinternal PhD, WU

Abstract

Background: Jiangsu Province is an economically booming area in East China, where soil zinc concentrations are low. Nutrition transition to a dietary pattern with more animal source foods may have improved zinc intake in this area. However, such a transition may also have increased the burden of non-communicable diseases (NCDs), such as hypertension and obesity. Investigation of dietary patterns in relation to undernutrition and overnutrition could help to better address both problems.

Objectives: The first aim of this thesis was to assess zinc status in Jiangsu Province using dietary zinc intake, serum zinc and stunting as indicators, as well to investigate the potential of biofortified rice to improve zinc intake. The second aim was to investigate the association between dietary patterns and high blood pressure, taking obesity into account.

Methods:Data from the 2002 National Nutrition and Health Survey in Jiangsu Province were used to assess zinc intake in the population aged 4-89 years (n=3,867). Primary school children (n=2,268) were selected from three counties in the Province with relatively low soil zinc for assessment of stunting. Serum zinc was measured among children in the county where stunting was highest (n=297).  Thirteen women were recruited in the same county for three test rounds with rice meals (zinc biofortified rice, zinc extruded fortified rice and control rice). Fractional zinc absorption (FAZ) was measured with the use of the double isotope tracer ratio method. Effect of biofortified rice with zinc, at a level of 2.7 and 3.8 mg/100g, on zinc intake was simulated in adults (n=2.819). For adults, four distinct dietary patterns were identified, named “traditional”, “Macho”, “sweet tooth” and “healthy” pattern. Associations were assessed between the four dietary patterns and blood pressure in adults (n=2,518) by using Poisson regression analysis.

Results:The overall prevalence of insufficient intake of zinc was 22.9%, with a higher prevalence in children (64.6%) and adolescents (64.9%), and in those with low socio-economic status (27.3%). Around 4% of the primary school children were stunted, and the prevalence of zinc deficiency measured by serum and hair zinc was 0.7%, and 15.2%, respectively. Biofortified 70Zn enriched rice with an intrinsic label was found to have higher fractional zinc absorption (FAZ) than extrinsically labeled fortified extruded rice. However, FAZ could not be accurately quantified because we could not determine the exact amount of isotope infused to subjects due to adhesion of zinc to the vial. When simulating zinc intake by replacing normal rice with zinc biofortified rice with either 2.7 and 3.8 mg/100g of zinc, the prevalence of insufficient zinc intake decreased from 15.4% to 6.5% and 4.4%, respectively. The “traditional” dietary pattern in Jiangsu Province was most strongly associated with high blood pressure (P for trend = 0.005). This pattern is characterized primarily by consumption of rice and fresh vegetable; secondary of pork and fish; and lastly of root vegetable and wheat flour, but also by high salt intake. Subjects with overweight and obesity were more likely to have high blood pressure than those with normal weight.

Conclusion: Children and adolescents had low dietary zinc intake, in Jiangsu Province, where the soil is also deficient in zinc. However, these findings did not match with the low prevalence of stunting and zinc deficiency based on serum zinc concentrations in primary school children from three rural areas of the Province. Zinc appears to be better absorbed from biofortified rice than from control rice or from extruded fortified rice, which needs further investigation. Simulated zinc intake from biofortified rice with zinc at a level of 2.7 mg/kg has the potential to significantly improve zinc intake, especially in the “traditional” dietary pattern. However, this pattern is also related to high blood pressure, which may be due to high salt intake. High blood pressure is also positively and independently related to obesity. Nutrition education is required to improve knowledge and awareness of healthy diets in Jiangsu Province.

 

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Kok, Frans, Promotor
  • Zimmermann, Michael, Promotor
  • Melse-Boonstra, Alida, Co-promotor
  • Zhao, J.K., Co-promotor, External person
Award date1 Oct 2012
Place of PublicationS.l.
Print ISBNs9789461733740
Publication statusPublished - 2012

Keywords

  • zinc
  • nutritional state
  • fortification
  • diet
  • hypertension
  • obesity
  • china

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