Posted Sept 6, 2010

Take note, kids. What you do to your body today really could hurt you a few decades from now.

A new study that followed more than 3,000 young adults into middle age found that people who had high cholesterol in their 20s were much more likely to show early signs of atherosclerosis in their 40s than those who had “optimal” cholesterol levels.

That may seem kind of obvious — after all, anyone who has high cholesterol in his 20s is likely to have high cholesterol in his 40s and 50s, too. What’s compelling, researchers say, is that the study suggests that the people may actually be doing irreversible harm in their youth.

“You have to start thinking about cholesterol levels early in life, because what you do early in life matters later on. You can’t put these things off until later,” said Dr. Mark Pletcher, an epidemiologist and biostatistician at the University of California at San Francisco who was the lead author of the study. The study was published in Monday’s edition of the Annals of Internal Medicine.

It has long been assumed, at least by young adults, that whatever damage they do to their bodies in their 20s can be magically erased, or at least mostly undone, by improving their health in their 30s and 40s.

But the new study, which included research out of the San Francisco campus and Kaiser Permanente in Oakland, Calif., suggests that the harm done by high cholesterol starts early and builds over time. Young people may not realize they’re causing long-term damage and setting themselves up for heart disease later in life, researchers say.

The results are particularly compelling now, as several recent studies have found that most Americans in their 20s — and many teenagers, too — have high cholesterol. In fact, in the new study, more than 75 percent of participants had high cholesterol in their 20s and 30s, and only 13 percent maintained optimal cholesterol levels through their young adulthood.

Yet most in their 20s have no idea whether their cholesterol is high, doctors say. National guidelines recommend that everyone have their cholesterol checked at age 20, but many young adults don’t see their doctors for regular checkups and don’t go out of their way to get tested for heart disease indicators like cholesterol or blood pressure.

“Young folks don’t necessarily come to the doctor very often, and they’re not focused on preventing problems two or three decades later,” said Dr. Anthony Steimle, chief of cardiology at Kaiser Permanente in Santa Clara, Calif., who was not involved with the study. “The good news is it’s never too late to modify your lifestyle. But you probably can’t completely undo the effects of a decade or two of bad lifestyle. It’s best to begin (a good lifestyle) at a very young age.”

The new research came from a national study that has followed 3,258 people over 25 years to assess their risk of heart disease over time. The participants were ages 18 to 30 when they joined the study in 1985. They come from four U.S. cities — Kaiser Oakland is one of the participating centers.

The cholesterol research was based on follow-up exams with participants in 2005. The research looked at participants’ average cholesterol levels between ages 20 and 35, their cholesterol level at the follow-up exam, and the amount of coronary calcium in their arteries, which is a strong predictor of future heart disease.

Of the 434 participants who maintained optimal cholesterol levels through age 35, only 8 percent had coronary calcium in theirs 40s. For the 2,443 participants who had high cholesterol, 44 percent had coronary calcium.

The fact that high cholesterol at a relatively young age was connected to later coronary calcium — whether or not individuals had high cholesterol later in life — was a “missing link” in research into heart disease risk and age, Pletcher said.

“Before our study, you could have made the argument that it’s very clear that your cholesterol level right now predicts your heart disease tomorrow,” Pletcher said. “This study links exposure during young adulthood with damage that lasts into middle age.”

Whether young adults should be put on cholesterol-lowering medications is a question worth pursuing, researchers said. The drugs might improve long-term risk of heart disease, but it is not clear if there are health hazards associated with decades of exposure to such drugs.

But the results suggest that at the very least, young adults should find out their cholesterol levels and, if necessary, try to lower those levels through diet and exercise, doctors and researchers said.

“It’s important to look at yourself when you’re a young person, because heart disease is really a lifelong disease,” said Dr.

Steve Sidney, associate director for clinical research at Kaiser Northern California, who was one of the study authors. “It can start in childhood. But it doesn’t manifest itself in heart attack or stroke until decades later.”

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