Writing in the Annals of Internal Medicine, the researchers say their findings contradict the common assumption that cholesterol levels in early life are insignificant, prompting them to suggest that early intervention may be important.
"Our evidence shows that young adulthood is an important time because lasting damage already starts to accumulate at this age," said Mark Pletcher, lead author and associate professor of Epidemiology & Biostatistics and of Medicine at the University of California, San Francisco.
The study, which followed 3,258 adults for two decades, found that the majority of people who had elevated cholesterol levels in their 20s and 30s went on to develop coronary calcium – an indication of atherosclerotic plaque build-up in the coronary arteries.
"In order to prevent heart disease and stroke more effectively, we should be thinking about cholesterol at a younger age," said Pletcher.
Healthy in 1985
Recruited in 1985, the study participants were all healthy men and women aged 18 to 30 of various backgrounds from four American cities. Just over half of the participants were women, and just under half of all participants were black.
Throughout the 20-year study period, researchers tracked LDL and HDL cholesterol, as well as triglycerides in the blood. When participants reached their mid-forties, their coronary artery calcium was measured using a CT scan.
Results indicated that coronary calcium was more likely to develop in people with elevated LDL cholesterol in earlier life.
Some 44 per cent of study participants with an average LDL cholesterol level greater than 160 mg/dL had calcifications in their coronary arteries two decades later, compared to only 8 per cent of participants with optimal LDL levels less than 70 mg/dL, said the researchers.
They found that even modest rises in LDL – as low as 100-129 mg/dL – were associated with a significantly higher risk of atherosclerosis. The majority of young adults studied (65 per cent) had LDL levels higher than 100 mg/dL.
The researchers said the long-term nature of their study allowed them to clarify the effects of exposure at different times during a person’s life.
“Until now, the medical community did not know the consequences of exposure to non-optimal lipid levels during young adulthood because it is difficult to disentangle the effects of exposure early in life from exposure later in life when heart disease becomes evident.”
"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."
They concluded that 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."
Annals of Internal Medicine; August 2, 2010
Authors: Mark J. Pletcher, Kirsten Bibbins-Domingo, Kiang Liu, Steve Sidney, Feng Lin, and Eric Vittinghoff