Young adults whose cholesterol levels are even slightly higher than normal are at greater risk of developing artery-clogging calcium deposits later in life, which can trigger hardening of the arteries leading to heart disease, a new study suggests.
This conclusion runs counter to the common assumption that modestly high cholesterol levels are nothing to worry about in young adults. Equally important, it argues that people need to start eating healthy and exercising early to prevent heart disease, the researchers say.
"You can't just ignore your cholesterol levels until you get into middle age. You have to be thinking about them and having a healthy diet and exercise regimen even early in life when you are at low risk for heart attacks," said lead researcher Dr. Mark J. Pletcher, an assistant professor in the department of epidemiology and biostatistics at the University of California, San Francisco.
Pletcher recommends diet and exercise as a way to control cholesterol, because the use of cholesterol-lowering drugs such as statins in young adults is controversial. People should start having their cholesterol checked when they are in their 20s, he said, and they should start a healthy diet and exercise program at the same time.
The report is published in the August 2 issue of the Annals of Internal Medicine.
For the study, Pletcher's team collected data on almost 3 300 men and women 18 to 30 years old participating in the CARDIA (Coronary Artery Risk Development in Young Adults) Study. Participants in the prospective study - recruited from four different US cities - were comprised of black and white men and women who were healthy when they enrolled. Over a period of 20 years, they had their low- and high-density lipoprotein (LDL and HDL) cholesterol and triglycerides levels measured repeatedly.
After 20 years, the researchers performed scans looking at coronary artery calcium, which is a measure of calcium deposits in the coronary arteries. The average age at the time of the scan was 45. Coronary calcium deposits - a risk factor for heart disease - were present in 17 percent of the participants, or nearly one in five.
People whose "bad" cholesterol (LDL cholesterol) was high when they were in their 20s were more likely to have calcium lining their coronary arteries after age 35, the researchers found. In a subset of participants without abnormal blood fat levels who were not taking lipid-lowering medicine, low levels of good HDL cholesterol were also associated with a higher risk of calcifications.
For example, 44 percent of those with an average LDL of more than 160 milligrams per deciliter (mg/dL) when they were young had plaque buildup in their coronary arteries 20 years later, compared with 8 percent of those whose LDL levels were less than 70 mg/dL, Pletcher noted.
Even a modest rise in LDL, as low as 100-129 mg/dL, was associated with a higher risk of atherosclerosis, the researchers said. Sixty-five percent of the young adults had LDL levels greater than 100 mg/dL, they added.
The study had some limitations, the researchers noted in the Annals of Internal Medicine. "Coronary calcium, although a strong predictor of future coronary heart disease, is not a clinical outcome," they wrote.
The researchers also wrote that "safety concerns [about cholesterol-lowering treatments] are rightly magnified when starting treatment early in life is considered." The findings, they said, "cannot provide evidence for the effectiveness or safety" of using cholesterol-lowering drugs, such as statins, during young adulthood, although they added that could be an area for further investigation.
"It is an active area of debate," Pletcher said, adding that new guidelines are expected next year that will consider the use of statins in young adults.
Although drug therapy might be useful, Pletcher added, "there is no firm evidence that treating people with statins during young adulthood is overall beneficial, because it would require treating people for 30 to 50 years before any benefit in terms of heart attack prevention would occur."
Dr. Gregg C. Fonarow, a professor, medicine and director of the Ahmanson-UCLA Cardiomyopathy Center at the University of California, Los Angeles said that "it has been very well established that atherosclerosis begins in childhood and progresses during adolescence and young adulthood, resulting in more advanced lesions in middle-aged and older adults."
The atherosclerosis disease process begins with lipids accumulating in the artery wall and ultimately may result in more advanced lesions that rupture, leading to heart attacks, he said.
"These results and prior studies lend support for the public health strategy of beginning risk-factor control in youth and continuing it life-long through improved cardiovascular health behaviours," Fonarow said.
In terms of what can be done, Fonarow said that "lifestyle changes are the mainstay of lipid and other cardiovascular risk factor modification in youth".
Fonarow added that cholesterol-lowering drugs should be used only in young people who have very high cholesterol levels.
"According to current guidelines, statins or other cholesterol lowering medications should generally be reserved for pediatric patients with very high LDL levels, with careful assessment of the risks and benefits of drug treatment," he added. - (HealthDay News, August 2010)