| Abstract |
Background: This thesis presents the first study to analyze and evaluate data collected
from two representative cross-sectional studies conducted among Caucasian Cretan
children from Greece registered in the first grade of the elementary school during the
academic years 1992/93 and 2006/07. The study examined secular changes in
anthropometric measurements, blood pressure (BP), moderate to vigorous physical
activity (MVPA), physical fitness (PF), inactivity (TV-viewing) and the dietary habits of
children in order to observe the progression of childhood obesity in Crete during 1992/93
and 2006/07.
Methods and materials: Two representative groups of 967 children in total, aged 5.9-7.8
years, were studied during 1992/93 and 2006/07 school years. Both studies were
conducted by the Preventive Medicine and Nutrition Clinic of the University of Crete.
Children in the 1992/93 study cohort were selected from a total population of 1098 first
grade children participating in the 6-year, school-based “Cretan Health and Nutrition
Education program” an intervention study focusing on children's diet and physical
activity. For the purposes of the present study, the baseline measurements of 323 boys
and 283 girls (aged 5.9–7.8 years) were selected for further analyses. Children in the
2006/07 cohort were selected from a population of 798 1st, 2nd, and 3rd-graders
participating in a 1-year intervention on diet and physical activity in schools in the
prefecture of Chania. From this study, the measurements of 361 1st-graders (199 boys
and 162 girls) were selected and these subjects were matched for gender, age, and area of
residence (urban, rural and suburban) with the 1992/93 cohort before the educational
intervention program in both periods. Body weight, height body mass index (BMI), waist
circumference (WC), waist to hip ratio (WHpR), Conicity index, blood pressure (BP),
were assessed. The moderate to vigorous physical activity (MVPA) was also assessed
with a 3 day physical activity (PA) questionnaire on which children were asked to record
the time spent on vigorous physical activities. PF was assessed with the use of the Eurofit
tests battery protocol. Estimated three-day food records were used to assess food
consumption and dietary habits. Estimation of the prevalence of obesity was performed.
Data on the frequency of TV-viewing was also collected.
Results: During the last fifteen years there has been a significant increase in all markers
in physical activity, and cardio-respiratory endurance. Between 1992/93 and 2006/07,
there was a significant increase in all fitness tests in both genders (p<0.001) and in the
MVPA for boys (76.5 min/week vs. 38.7 min/week, p<0.001). In 2006/07, active boys
and active girls spent more time in MVPA than active boys and girls in 1992/93
(p<0.001) with a simultaneous significant but alarming increase in time spent watching
TV on weekdays (P<0.001). There was a significant increase (p<0.01) in body weight
(+10.2% and +6.7%), BMI (+6.9% and +4.0%), WC (+5.6% and +5.1%), and WHpR
(+3.0% and +3.4%), for boys and girls, respectively, and in the proportion of
overweight/obese boys (19.4% vs. 33.7%; p<0.001) between 1992/93 and 2006/07. For
both genders the BP decreased in 2006/07 compared to 1992/93 (p<0.001). However in
both periods, BP was higher in obese compared to overweight and normal children
(p<0.001), but there was no relationship between BP and PA. During the15-year period,
both genders significantly increased their energy intake-(EI) (boys: +167 kcal, p=0.014;
girls: +167 Kcal, p=0.028), total-fat (boys: p=0.028, girls: p=0.019), protein (boys:
p<0.001, girls: p=0.007), calcium and iron (p<0.001). A higher proportion of the 2006/07
group exceeded 120% of the Recommended Energy Allowance (REA) for energy (34.5%
vs. 20.5%, p<0.001). Dairy products increased respectively in proportion to EI (≤100%,
101-120% and >120% of REA); 220, 284 and 308g for the 1992/93 group (ptrend=
0.001) and 272, 427 and 429g for the 2006/07 group p-trend<0.05). Both genders
significantly increased their intake of dairy products (p<0.001), decreased their intake of
cereals (p<0.001). Among girls, fruit/vegetable consumption increased (p<0.05), but
legume intake decreased (p<0.005). Among overweight/obese (ow/ob) children, dietary
energy density (ED) decreased significantly (p<0.05) and mean consumption of fruits/
vegetables increased (p<0.001). The percentage of ow/ob boys increased significantly
(p<0.001), however MVPA increased significantly in this group (p<0.001). The majority
of active children in 2006/07 had significantly lower dietary energy density (ED)
(p<0.001) than those in 1992/93.
Conclusions: Over the15-year period, a significant increase in obesity indices was observed
among Cretan children with conflicting simultaneous increase in PA and cardio-respiratory
fitness. Moreover the increase in weekday TV-viewing is related to the prevalence of obesity
of that sample group. The effort to improve children’s eating habits by eating more
fruits/vegetables may constitute a positive trend however; it was well below
recommendations, which might also explain the weight increase in this group. The marked
downward cereal consumption in 2006/07 may have also resulted in the increase in obesity
for our sample which is certainly ineffective and harmful for the growth of the children
particularly with a lowering of complex carbohydrates. Frequent consumption of foods with
a high ED is associated with prevalence of obesity. The fall in BP observed during this
period may indicate an effort made by the children and their families to adopt a healthier
lifestyle by improving their food choices.
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