Secular Trends in Obesity and Serum Lipid Values among Children in Oita City, Japan, during a 27-Year Period

Aims: We assessed 27-year trends in obesity and blood lipid levels of 10-year-old children to estimate the risk of metabolic syndrome in adulthood. Methods: Based on a screening program for lifestyle-related diseases in school children in Oita City, Japan, we evaluated secular trends in height, weight, percentage of overweight (POW), total cholesterol (TC), triglyceride (TG), HDL cholesterol (HDL-C), and non-HDL cholesterol (non-HDL-C) of fifth graders (median age: 10.8 years) in Oita City from 1991 to 2017. We focused on the secular trend in the percentage of children with inappropriate serum levels of each lipid. We also evaluated the long-term trends in the 95(th), 50(th), and 5(th) percentiles for each parameter, as dependent variables, with the calendar year as an independent variable. Percentages of children with mild obesity (POW-20), moderate obesity (POW-30), and severe obesity (POW-50) were set as dependent variables. Results: A total of 58,699 boys and 56,864 girls were evaluated during the study period. The percentage of children with severe obesity (POW-50) consistently increased during these years, and the 95(th) percentile of degree of obesity significantly increased in both boys and girls. The plot of percentages of children with inappropriate levels of TC, TG, and non-HDL-C showed a mild inverted U shape during the study period. The HDL-C level typically decreased in the study period, and the TC, TG, and non-HDL-C levels were markedly higher while the HDL level was lower in obese children than in non-obese children. Conclusion: The number of children with severe obesity increased, and obese children had higher percentages of inappropriate lipid levels than non-obese children. The rate of dyslipidemia with low HDL levels gradually increased in all children in Oita City, Japan, over the past 27 years.