The national study covered 3,125 young people, whose blood test results were collected by the National Health and Nutrition Examination Survey from 1999 to 2006. The data included measurements of Low Density Lipoprotein (LDL or “bad” cholesterol), High Density Lipoprotein (HDL or “good” cholesterol), and triglycerides.
In adults, high cholesterol is a major risk factor for heart disease because LDL cholesterol and triglycerides can clog the arteries. It is also associated with high blood pressure, strokes and diabetes. Unhealthy levels were at first associated with the middle-aged and elderly, but are increasingly beginning to appear in late childhood and the teenage years.
The study found 20.3% of the subjects, aged 12 to 19, had at least one abnormal cholesterol or lipid level, with more boys than girls affected (24% to 16%). High levels of LDL or triglycerides, and low HDL levels were associated with weight, and the heavier the teenagers were, the more likely they were to have abnormal levels (42.9% if they were obese), but even among those with normal body weight 14.2% had unhealthy levels. About one-third of the young people were overweight or obese, and would therefore be eligible for cholesterol screening on this basis.
Leader of the study, Dr Ashleigh May, an epidemic intelligence service officer with CDC, described the results as “very concerning” and said that a large proportion of the young people had at least one abnormal level. May said they wanted to ensure doctors recommend lipid screening and lifestyle changes for young people, especially if they were overweight or obese. The study backs up a recommendation made by the American Academy of Pediatrics in 2008 that children and adolescents should have blood tests if they are overweight, smoke, have high blood pressure, or if there is a family history of elevated cholesterol levels. The guidelines were controversial at the time because they recommended cholesterol-lowering drug treatments for children as young as eight (two years younger than previously recommended).
May emphasized that the best ways to reduce the risk of heart disease in the future was for young people to be active and to follow a healthy eating regime.