Body composition, physical activity and C-reactive protein in children : the PLAY study

Abstract

Obesity is currently the most common and costly nutritional problem in developed countries and ten percent of the world's school-aged children are estimated to be overweight to some extent. Low-grade systemic inflammation is increasingly emerging as a significant component of the metabolic syndrome. Youth in lower income families are particularly vulnerable because of poor diet and limited opportunities for physical activity. In developing countries obesity among youth is rising among the urban poor, possibly due to their exposure to Westernised diets coinciding with a history of under-nutrition. The aim of this study was to assess the association between serum CRP and physical activity and to assess the association between serum CRP and body composition in black high-school children from a township in the North West Province (NWP), South Africa. Methods and results: The study group consisted of 193 school children between the ages 13 to 18 years (78 boys and 115 girls) residing in lkageng, the township outside of Potchefstroom in the North West Province, South Africa. Children were from a black ethnic group, living in a poor socioeconomic setting. Demographic and body composition measurements were taken and fasting blood samples were drawn for serum C-reactive protein (CRP) measurements. The difference between serum CRP of overfat versus girls with a normal fat percentage was non-significant (p = 0.46). Boys with body fat percentage >20% (n=16) had .a mean serum CRP of 1.42 2.16 mg/L and for boys with a normal fat percentage (n=53) mean serum CRP was 0.89 k 1.62 mg/L. The Mann-Whitney U-test for the difference between mean CRP of the two groups of boys was Z=1.39, p=0.16 (no significant difference), but with a trend of higher serum CRP concentration in the boys with higher % body fat. For the boys, the only positive partial correlation was between serum CRP and triceps skinfold (r=0.327, p=0.045). In the girls' group no statistically significant partial correlations were found between CRP and body composition variables. There was no significant difference between serum CRP concentrations of the three physical activity categories of girls. Interestingly, there was an inverse correlation between percentage body fat and fitness in the boys' group (r=-0.509 and p= 0.008). The difference in log CRP between activity groups showed a trend of lower serum CRP with higher physical activity in the girls. Conclusion: This study showed no statistically significant associations between serum CRP and body composition, except for the positive correlation between triceps skin fold and serum CRP in boys, or CRP and physical activity, but clear trends were noted of an inverse association between CRP and physical activity in the girls.