CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 9, October 2012
AFRICA
501
Elevated salivary C-reactive protein predicted by low
cardio-respiratory fitness and being overweight in
African children
T NAIDOO, K KONKOL, B BICCARD, K DUBOSE, AJ MCKUNE
Abstract
Introduction:
C-reactive protein (CRP) is a sensitive marker
of systemic inflammation and is an independent risk factor
for cardiovascular disease. The aim of the study was to exam-
ine the relationship between salivary CRP, cardio-respiratory
fitness and body composition in a paediatric population.
Methods:
This was a cross-sectional study of 170 black South
African children (age 9.41
±
1.55
years, 100 females, 70 males)
in grades 3 to 7. Unstimulated whole saliva samples were
obtained for the analysis of CRP.Height,mass, skin-fold thick-
ness, resting blood pressure, and waist and hip circumference
measurements were obtained. Cardio-respiratory fitness
was assessed using a 20-m multi-stage shuttle run. Children
were classified as overweight/obese according to the Center
for Disease Control and Prevention (CDC) body mass index
(
BMI) percentile ranking, and meeting percentage body fat
recommendations, if percentage body fat was
≤
25%
in boys
and
≤
32%
in girls. The cut-off point for low cardio-respira-
tory fitness was a predicted aerobic capacity value
≤
the 50th
percentile for the group. Contributions of low cardio-respir-
atory fitness, overweight/obesity, and not meeting percentage
body fat recommendations, to elevated salivary CRP (
≥
75
th
percentile) concentration and secretion rate were examined
using binary logistic regression analysis with a backward
stepwise selection technique based on likelihood ratios.
Results:
Poor cardio-respiratory fitness was independently
associated with elevated salivary CRP concentration (OR 3.9,
95%
CI: 1.7–8.9,
p
=
0.001).
Poor cardio-respiratory fitness
(
OR 2.7, 95% CI: 1.2–6.1,
p
=
0.02)
and overweight/obesity
(
BMI
≥
85
th percentile) (OR 2.5, 95% CI: 1.1–5.9,
p
=
0.03)
were independent predictors of elevated salivary CRP secre-
tion rate.
Conclusion:
The results suggest a strong association between
poor cardio-respiratory fitness and/or overweight/obesity
and inflammatory status in children, based on elevated sali-
vary CRP levels.
Keywords:
inflammation, C-reactive protein, body composition,
children, cardio-respiratory fitness
Submitted 20/2/12, accepted 6/8/12
Cardiovasc J Afr
2012;
23
: 501–506
DOI: 10.5830/CVJA-2012-058
Inflammation has been hypothesised as a potential mediator
of the association between obesity, physical inactivity and the
development of chronic diseases, such as cardiovascular disease
(
CVD), type 2 diabetes, depression and cancer.
1
Low-grade
systemic inflammation, a condition marked by a chronic two-
to three-fold increase in circulating inflammatory markers,
2
is
considered important in the chronic disease process through
promoting the development of insulin resistance, atherosclerosis,
neurodegeneration, and tumour growth.
3
Systemic C-reactive
protein (CRP) is a sensitive marker of low-grade systemic
inflammation and is an independent risk factor for CVD.
4-6
It is
therefore important to characterise the determinants of individual
differences in inflammatory markers such as CRP.
7
The current worldwide pandemic of childhood obesity
and low levels of cardio-respiratory fitness (CRF) makes the
understanding of inflammation and interventions to reduce
inflammation, important areas of research.
8,9
Obese children
have higher levels of systemic CRP compared to children of
normal weight, suggesting that chronic low-grade systemic
inflammation is an early complication of childhood obesity.
8
In
addition, elevated systemic CRP in young children is a risk factor
for the development of the metabolic syndrome.
9
Research has revealed an association between elevated
systemic CRP and low CRF.
10
By contrast, several studies show
that systemic CRP is lowered by a reduction in visceral fat mass
and/or increased physical activity or exercise.
11,12
In healthy,
pre-pubertal children, elevated CRF was shown to protect against
low-grade inflammation.
10
There is limited research in this area in Africa, although a
recent study of black South African adolescents reported a trend
for increased levels of serum CRP in individuals with a higher
percentage body fat.
13
The study also found a negative correlation
between fitness levels and serum CRP.
13
However, the investigation of inflammatory levels is delayed
by the lack of non-invasive methods to assess inflammation that
would enable research in large representative populations and in
children.
7
The investigation of inflammatory biomarker levels are
commonly measured in blood collected through venipuncture.
However, venipuncture is an invasive procedure and requires
skilled professionals, laboratory equipment and considerable
financial resources.
7
By contrast, saliva collection is non-invasive,
stress- and pain-free and constitutes an alternative strategy to
prospectively assess immune activity in large samples.
7
The measurement of biomarkers in saliva to examine
Department of Biokinetics, Exercise and Leisure Sciences,
School of Health Sciences, University of KwaZulu-Natal,
Durban, South Africa
T NAIDOO, BSpSc
K KONKOL, MA
AJ MCKUNE, DTech,
Perioperative Research Group, Department of Anaesthetics,
Nelson R Mandela School of Medicine, University of
KwaZulu-Natal, Durban, South Africa
B BICCARD, MB ChB, FCA (SA), FFARCSI, MMed Sci, PhD
Physical Activity Promotion Laboratory, Department of
Kinesiology, East Carolina University, USA
K DUBOSE, PhD
