Cholesterol levels drop in kids but reasons are unclear

With all the ills that have come from the childhood obesity epidemic, one surprise finding provides a small glimmer of hope that kids aren’t doomed to a shorter life expectancy than their parents: Cholesterol levels have dropped in children over the past 20 years, according to a government survey published today in the Journal of the American Medical Association.

The study, which analyzed blood samples collected from more than 16,000 young people from 1988 to 2010, found that about 8 percent of participants aged 6 to 19 had high total cholesterol levels in 2010 compared with more than 11 percent who had elevated cholesterol at the beginning of the study. Researchers also found a corresponding rise in “good” HDL cholesterol levels and a decrease in levels of harmful triglycerides, another component of cholesterol that’s often tied to excess sugar consumption.

“I think that’s an important decrease,” said study leader Dr. Brian Kit, a medical epidemiologist at the Centers for Disease Control and Prevention. But it’s one that the researchers couldn’t fully explain given the expansion of kids’ waistlines and their propensity to sit in front of television and computer screens, when they once spent free time running around outdoors.

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“It’s important to remember that cholesterol levels are impacted by a variety of factors, besides physical activity and obesity,” added Kit.

While cholesterol-lowering medications such as statins have probably contributed to improvements in adult cholesterol levels, very few children are taking these drugs.

Some factors that may be contributing to improved cholesterol levels? Parents and teens are smoking less than they were two decades ago, and this may have led to an overall rise in HDL, said Dr. Sarah de Ferranti, director of preventive cardiology at Boston Children’s Hospital who wrote an editorial that accompanied the study.

We’ve also cut back on trans fats, the stuff in Crisco (remember that?) and other partially hydrogentated oils such as margarine. Boston banned the use of trans fats in restaurants several years ago, and food manufacturers have been taking them out of crackers, cookies and other baked goods.

“Crisco and other trans fats used to be big players in our bad cholesterol levels,” said de Ferranti, because they triggered a rise in LDL levels—the “bad” cholesteroal—while simultanerously lowering HDL.

Americans have cut the overall percentage of fat in their diets in favor of more carbohydrates, but what impact this may have had on our cholesterol levels remains unknown. After all, kids are eating far more sugar than they used to, so this should have led to a rise in triglyeride levels—which doesn’t seem to be the case from the latest study.

“We need to dig down to better understand the reasons for the decline,” said de Ferranti. “It doesn’t mean we’ve solved the cholesterol problem in kids, but we need to think of other ways to shift their eating patterns and physicial activity levels to improve cholesterol even more.”