Elsevier

Atherosclerosis

Volume 203, Issue 1, March 2009, Pages 311-319
Atherosclerosis

Lifestyle and environmental factors associated with inflammation, oxidative stress and insulin resistance in children

https://doi.org/10.1016/j.atherosclerosis.2008.06.022Get rights and content

Abstract

Background

Reaching a better understanding of the modifiable factors associated with inflammatory and oxidative biomarkers in children would be relevant to the design of further investigation and prevention strategies.

Objective

To determine the association of air pollution as well as dietary and physical activity habits with markers of inflammation, oxidative stress and insulin resistance for the first time in a population-based sample of children.

Methods

We conducted a population-based study of 374 children, aged 10–18 years, and assessed the exposure of participants to air pollutants as well as their dietary and physical activity habits. In addition to anthropometric and blood pressure measurements, we determined the fasting serum levels of lipid profile, insulin and markers of inflammation and oxidation.

Results

We found independent associations between improper air quality and plasma markers of inflammation, oxidative stress and insulin resistance. The Pollutant Standard Index (PSI) and the level of fine particulate matter were significantly associated to all biomarkers studied. The associations between different markers of air pollutants and markers of inflammation, oxidative stress and insulin resistance remained significant after adjustment for age, gender, body mass index, waist circumference, healthy eating index and physical activity level. The association of healthy eating score with CRP and insulin resistance was mediated through anthropometric indices, and physical activity had independent association with insulin resistance.

Conclusion

The independent influence of inflammatory/oxidative mechanisms of air pollution effects on surrogate markers of atherosclerosis from early life should be highlighted.

Introduction

Primordial and primary prevention of atherosclerosis might be effective for prevention of the development of atherosclerotic diseases [1]. Inflammation is thought to play a central role in the pathogenesis of atherosclerosis and consequently coronary heart diseases (CHD) [2]. As documented by the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study, immunological-inflammatory cells are present in the earliest stages of atherogenesis [3].

Markers of inflammation, as C-reactive protein (CRP), are associated with an increased risk of incident CHD. The causes of increased CRP, however, are not completely understood. It is suggested that oxidative stress may be a determinant of CRP levels and is suggested to promote pro-atherosclerotic inflammatory processes in adults [4] and children [5]. Studying the early relationships between markers of inflammation and atherosclerosis would help to better understand the pathogenesis.

Although the biologic mechanisms responsible for the association of inflammation and oxidative stress with CHD remain to be fully understood, reaching a better understanding of the modifiable factors associated with increasing levels of these biomarkers in children would be relevant to the design of further investigation and prevention strategies.

A seamless progression of the effects of the modifiable risk factors on atherosclerosis is documented from childhood [6]. The few studies that have assessed the contribution of lifestyle factors to markers of inflammation among adult population revealed conflicting results [7], [8], [9]. Similar studies among youth have been limited to obese children [10], [11], and no previous population-based study has been conducted in this age group.

The association between air pollution and cardiovascular and other chronic diseases may be mediated through systemic inflammatory responses [12], [13]. Air pollution may result in the formation of reactive oxygen species that contribute to a decline in cellular function. Generation of these substances is linked to a variety of environmental factors. The effect of air pollution with inflammation/oxidative stress has been demonstrated in in vitro[14] and in vivo[15] studies, as well as in patients with cardiovascular disease [16], and in young adults [17], but it has not been assessed in children who might have the early stages of atherosclerosis [3], [6].

Long-term longitudinal studies have documented that metabolic syndrome/insulin resistance in childhood is associated with increased risk of CHD in adulthood, reactive oxygen species are considered to have a pivotal role in mediating inflammation in the metabolic syndrome [18]. Metabolic syndrome, although more prevalent in overweight individuals, but is also present in normal-weight children [19]. Determining modifiable associated factors with insulin resistance may be important for planning preventive measures.

The aim of this study was to determine the association of dietary and physical activity habits as well as air pollution with markers of inflammation, oxidative stress and insulin resistance in a population-based sample of children in order to have a better understanding of the potentially modifiable risk factors and environmental exposures associated with inflammatory processes linked to atherosclerosis in its early stages.

Section snippets

Study population

Study subjects were selected from among participants of a community-based cross-sectional study of risk factors for CHD among children aged 10–18 years [5] living in Isfahan, the second largest city in Iran. Individuals were eligible if they were living in those urban areas of Isfahan city with air pollution monitoring stations, have stayed in the same area for at least 1 week prior to the study, were non-smokers and lived with nonsmokers. Children with chronic disease, long-term medication use

Results

In this study, 374 children and adolescents including 191 boys and 183 girls, aged 10–18 years, with a mean age of 13.7 ± 2.5 years were studied. Of children studied, 12% were underweight, 9% were at risk of overweight and 7% were overweight. The metabolic syndrome was detected in 14.1% of participants.

Table 1 presents the mean (S.D.) values of the participants’ characteristics and air pollution data. Anthropometric measures, serum CRP and oxidative stress markers were not significantly different

Discussion

In this study, that is the first of its kind in the pediatric age group, the association of lifestyle and environmental factors with biomarkers of inflammation, oxidation and insulin resistance were assessed. Of special interest in the context of this study was our finding on independent associations between improper air quality and plasma markers of inflammation, oxidative stress and insulin resistance. Furthermore, we found that the association of HEI score with CRP and HOMA-IR was mediated

Conclusion

The independent influence of inflammatory/oxidative mechanisms of air pollution effects on surrogate markers of atherosclerosis from early life should be highlighted. Further longitudinal investigations are needed to confirm these associations.

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