A 20-year study published in the Annals of Internal Medicine refutes the common assumption that non-optimal cholesterol levels are insignificant during young adulthood and suggests a stronger emphasis on early lifestyle intervention.

Researchers at the University of California San Francisco followed 3,258 men and women aged 18 to 30 for two decades with repeated measurements of LDL and HDL cholesterol as well as triglycerides. At the end of the study, participants had their coronary artery calcium, which is indicative of atherosclerotic plaque buildup in the coronary arteries, measured by a CT scan.

They found that individuals exposed to higher levels of LDL ("bad") cholesterol or lower levels of HDL ("good") cholesterol during young adulthood were more likely to develop coronary calcium.

Atherosclerosis, or blockages in the coronary artery from cholesterol and plaque, can lead to heart attack and stroke.

"The study shows that cholesterol levels in young adults are more important than we previously believed, because even the moderate non-optimal levels that are present in most young adults may alter their health decades later," said the study’s lead author, Stephen Hulley, M.D. "For many people in their 20s and 30s, it probably matters in the long run what they eat and how much they exercise, even though their risk for having a heart attack in the short term is low."