Cholesterol Levels Decling Among US Youths

According to a new report by CDC, the cholesterol levels has improved among the children in the United States over the past two decades despite the mounting obesity rates during the same period.

The study involving more than 16,000 U.S. children and adolescents showed a decline in average total cholesterol levels over the past two decades, although 1 in 10 had elevated total cholesterol in 2007-2010.

The researchers found that during the 1988 to 1994 and the 2007 to 2010 time periods, the children and teens experienced a decrease in total cholesterol levels and an increase in levels of 'good' HDL cholesterol.

The total cholesterol levels decreased from 165 milligrams of cholesterol per deciliter of blood from 1988 to 1994, to 160 milligrams per deciliter between 2007 and 2010, researchers found. MyHealthNewsDaily reported that 200 milligrams of cholesterol per deciliter of blood is considered 'high' for kids.

The number of 6- to 19-year-olds with high total cholesterol decreased from 11.3 percent to 8.1 percent between the 1988 to 1994 time range and the 2007 to 2010 time range, researchers also found.

"The process of atherosclerosis begins during childhood and is associated with adverse serum lipid concentrations including high concentrations of low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), and triglycerides, and low concentrations of high-density lipoprotein cholesterol (HDL-C). Serum lipid concentrations in childhood are associated with serum lipid concentrations in adulthood," according to background information in the article. "For more than 20 years, primary prevention of coronary heart disease has included strategies intended to improve overall serum lipid concentrations among youths."

"That's my leading theory," said Dr. Sarah de Ferranti, director of preventive cardiology at Boston Children's Hospital. She wrote an editorial that accompanies the study.

The study did not look at the reasons for the decline, but its lead author, Dr. Brian Kit of the Centers for Disease Control and Prevention, said the theory makes sense. Brain and colleagues had examined the trends in serum lipid concentration among children and adolescents in the U.S.

Published Tuesday in the Journal of the American Medical Association, the study involved data on 16,116 youths ages 6 to 19 years who participated in the nationally representative National Health and Nutrition Examination Survey (NHANES) that was held in 1988-1994,1999-2002, and 2007-2010.

The researchers analyzed the average serum total cholesterol (TC), non-HDL-C, HDL-C; and among adolescents only (ages 12-19 years), LDL-C and geometric average triglyceride levels.  Trends in adverse lipid concentrations were reported for TC levels of 200 mg/dL and greater, non-HDL-C levels of 145 mg/dL and greater, HDL-C levels of less than 40 mg/dL, LDL-C levels of 130 mg/dL and greater, and triglyceride levels of 130 mg/dL and greater.

Focusing on the obesity levels that have been rising, the CDC noticed that 17 percent of the children are obese, triple the level three decades ago.

"There are a lot of factors that can cause changes in blood cholesterol levels," said Kit. "One possible factor is a drop in adolescent smoking rates and lower exposure to secondhand smoke. Some studies have shown that exposure to smoking can reduce good cholesterol. Another factor is the decline in the consumption of trans fat."

New York City banned artificial trans fats in restaurant food in 2008. California in 2010 became the first state to adopt such a ban. 

They also noticed that children and adolescents who had any type of cholesterol problem involving too little "good" cholesterol or too much of the "bad" fell to 22 percent in the 2007-10 period from 27 percent in the 1988-94 period.

The recently released Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents provides recommendations for preventing the development of cardiovascular risk factors including optimizing nutrition and physical activity and reducing exposure to tobacco smoke.

Future research from longitudinal studies or mortality-linked data may include examining clinical outcomes for cardiovascular disease and mortality based on lipid concentrations present during childhood.

Seventeen percent of U.S. children are obese, perhaps because they are still eating lots of carbohydrates and sugar. That, along with little exercise, can lead to diabetes and heart disease.

"We may have a small effect in the right direction from lower cholesterol, but I'm worried it will be overwhelmed by the earlier onset of obesity in younger and younger children. I'm still pretty worried about how many kids are going to wind up patients of adult cardiologists," said De Ferranti.