Consider it a wake-up call for generations X and Y: You may think you are healthy, but having cholesterol levels that are even slightly high during your 30s may double your risk for heart disease later in life, new research shows.

People can lower their risk of developing heart disease by refraining from smoking and maintaining a healthy weight and blood pressure. But regardless of whether you do those things, if your cholesterol is above the healthy range starting in your mid-30s, you might be setting yourself up for a heart attack or chest pains by the time you're in your 60s, the results of the new study suggest.

Moreover, if you wait until you're 50 to lower your cholesterol, it may be too late to reverse the damage already done, the researchers said. Their message is for young adults to get their cholesterol level checked and, if it's high, do something about it now.

"Several of my co-authors and I are members of generations X and Y, so for us, this research wasn't just scientific; it's personal," said lead author Dr. Ann Marie Navar-Boggan of the Duke Clinical Research Institute, part of the Duke University Medical Center in Durham, N.C. "After I saw the results of our study, I called all of my family members between the ages of 20 and 50, and told them they needed to have their cholesterol levels checked."

Heart disease is the leading cause of death in the United States for both men and women, and is responsible for one in four deaths in the U.S., according to the Centers for Disease Control and Prevention. But fewer than half of adults ages 20 to 35 have had a cholesterol test, according to a 2010 CDC report. Cholesterol screening is not usually performed on young adults unless they have a risk factor for heart disease, such as obesity.

In this latest study, the researchers looked at data from the Framingham Heart Study, which has tracked the heart health of thousands of adults throughout their lifetimes, since 1948. The researchers focused on approximately 1,500 adults who are now in their 70s and who had been free of heart disease at age 55.

They found that the people in this group who'd had high cholesterol for at least 10 years by the time they reached age 55 had a 16.5 percent chance of developing heart disease after age 55. In comparison, people in the study who had normal cholesterol levels during those early years had a 4.4 percent risk of developing heart disease after age 55. [5 Surprising Ways to Be Heart Healthy]

Each decade of high cholesterol raised people's risk of heart disease by about 40 percent, suggesting that the cumulative effects of even mild or moderate elevations in cholesterol pose a significant risk to heart health, the study found.

The "wealth of data collected over time made it possible to analyze the long-term effects of cholesterol in young people a topic on which not enough is known because it requires decades of tracking," said Michael Pencina, a professor of biostatistics and bioinformatics at Duke and a senior author on the paper.

The researchers considered people to have elevated cholesterol if their levels were 160 mg/dL or higher for non-HDL cholesterol. Non-HDL is the total cholesterol minus the "good" HDL, leaving the "bad" LDL plus other types of harmful cholesterol. The researchers noted, however, that they found similar results for patients with LDL cholesterol of 130 mg/dL or higher.

Most experts agree that diet and exercise are the best methods of lowering your bad cholesterol and raising your "good" cholesterol. Numerous studies have shown that moderate physical exercise for 30 minutes a day can lead to at least modest improvements in a person's cholesterol profile; that is, some exercise is better than none, but more is much better than some.

Foods that can improve cholesterol levels include oats and other high-fiber grains; beans; oily fish, such as salmon; most nonsalted nuts; olive oil; and a plant-based diet in general.

And then there's the possibility of medication.

"Our research does not imply that all young adults in their 30s and 40s with high cholesterol should be on statins," which are cholesterol-lowering drugs, Navar-Boggan told Live Science. "We do not have great long-term data about the long-term safety and effectiveness of statin therapy when started in early adulthood for mild to moderately elevated cholesterol."

"That said, there are adults who will be unable to control their cholesterol with diet and exercise alone," Navar-Boggan said. "For these people, the decision to start statin therapy will ultimately be a personal one hopefully grounded in an informed conversation with their health care provider."

Other members of the research team are based at Boston University and McGill University in Montreal.

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