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Cholesterol levels that are above the ideal—but below the usual threshold for medication therapy—may put healthy adults at a higher lifetime risk of dying from cardiovascular disease, according to a new study published in Circulation.

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The research, which tracked more than 36,000 people over an average of 27 years, found that those with low-density lipoprotein (LDL, or “bad” cholesterol) that was borderline high were somewhat more likely to die from heart attacks and strokes than those with the lowest LDL levels. And those with high or very high LDL levels were much more likely to die.

The study focused exclusively on those people considered at low risk for cardiovascular disease based on age—most participants were under 50—and other factors such as as blood pressure, diabetes status, and tobacco use.

“When you’re young and healthy, you might be thinking, ‘How much do I have to worry about my cholesterol?’” says Christie M. Ballantyne, M.D., director of cardiovascular research and cardiology at Baylor College of Medicine in Houston, who wrote an editorial in Circulation about the study’s results. “Turns out, maybe it’s something you want to start paying attention to.”

But what does “paying attention to” mean in this context?  

What the New Findings Mean

Researchers at the Cooper Institute in Dallas recruited 36,375 healthy men and women who had their cholesterol levels checked from 1978 to 1998. Most of those who participated were under 50 years old.

Participants were divided into three groups: those with LDL levels below 100 mg/dl, those in the range of 100 to 159 mg/dl, and those with LDL of 160 mg/dl or higher. A LDL level of less than 100 mg/dl is considered healthy, 100 to 129 is near optimal/above optimal, 130 to 159 is borderline high, 160 to 189 is high, and 190 and above is very high, according to the National Heart, Lung, and Blood Institute.

Study subjects in the middle of the three groups were shown to have a 30 percent to 40 percent higher risk of cardiovascular-disease-related death than the group with the lowest LDL levels. Those with LDL levels of 160 mg/dl or higher were found to have a 70 to 90 percent higher risk than those with a level of 100 mg/dl or less.

“In the past, 190 mg/dl has been considered the threshold for very high risk, but this study showed significantly higher risk for anyone over 160,” says Ballantyne.

The researchers also found that study participants with higher levels of total cholesterol—a combination of LDL, high-density lipoprotein, or “good” cholesterol, and very low-density lipoprotein were at higher risk of death from heart disease.

The study does have its limitations. Because it is observational—where researchers compare large groups of people with each other—rather than a double-blind clinical trial (where participants are randomly assigned to a specific treatment, such as a medication), researchers were unable to control for all of the variables that may have affected their findings.

For instance, all of the participants were interested in improving their health and tended to be somewhat affluent, well-educated, and not particularly diverse, notes Shuaib M. Abdullah, M.D., an assistant professor of internal medicine at UT Southwestern and one of the study authors.

“Would the results have been different if we looked at a more general population group?” he asks. “It’s hard to know.”

The researchers also only had information on deaths, not on whether participants experienced nonfatal heart attacks or strokes.

In addition, several of the researchers have had financial relationships with pharmaceutical or medical-device companies, including those that market cholesterol-lowering medications.

What Should You Do?

While these findings are intriguing, neither the authors nor other experts suggest that younger, otherwise healthy people ask their doctors to prescribe statins, the class of medication commonly prescribed to help reduce LDL levels. Statins (which include drugs such as Crestor, Lipitor, Mevacor, Zocor, and their generics) can have significant short-term side effects such as muscle cramping, nausea, and headaches, with the potential for more serious effects over time. 

(Statins are thought to benefit people who have an LDL level of 190 mg/dl or higher, as well as those with a history of cardiovascular disease, or diabetes—if they're between age 40 and 75—and those with an estimated heart attack or stroke risk in the next 10 years of 7.5 percent or higher. That's according to 2013 guidelines from the American College of Cardiology and the American Heart Association.) 

“I would be concerned that this study could lead to more young people being prescribed statins,” says Michael Hochman, M.D., M.P.H., director of the Gehr Center for Health Systems Science at the Keck School of Medicine at USC in Los Angeles. “There haven’t been any long-term studies on them."

Researchers can't know whether participants who died might have fared better if they’d taken cholesterol-lowering drugs, says Abdullah. 

“The most important thing this study gives us is more data, which should open up discussions between patients and their physicians,” he explains. Abdullah suggests having a first cholesterol test in your 20s. (The American Heart Association recommends a first screening at age 20, with follow-ups every four to six years.)

Consumers should not only start paying attention to cholesterol levels in early adulthood but also adopt lifestyle strategies that can help them maintain ideal numbers, says Steven Nissen, M.D., chairman of the department of cardiovascular medicine at the Cleveland Clinic Foundation, who did not work on this study.

“Healthy diet alone has been shown to reduce bad cholesterol levels by 10 to 15 percent,” Nissen says.

The following steps have been shown to help:

Eat right. A heart-healthy diet should generally focus on whole grains, healthy fats, lean sources of protein, and an array of fruits and vegetables. Also, minimize your consumption of refined carbohydrates such as white flour, added sugar, and saturated fats. 

Strive for a healthy weight. Being overweight may contribute to high cholesterol, according to the National Institutes of Health. The NIH recommends that people trying to reduce their LDL levels take steps to lose extra pounds—especially if they have a body mass index above 25.

Get more physical activity. If you’re somewhat sedentary, increasing the amount of exercise you regularly get—even just walking more—is good for your overall health and has been linked to reduced cholesterol levels. Most public-health agencies recommend at least 30 minutes a day of moderate to vigorous exercise.

Kick the habit. Smoking hurts your heart in a variety of ways, including inflaming and causing swelling of the cells that line blood vessels, which can lead to a narrowing of the vessels and a higher heart attack risk. Smoking has also been found to exacerbate the negative effects of LDL on your heart. Aim to quit and get help if you need it.

Finally, listen to your healthcare provider. Get your cholesterol, blood pressure, and blood sugar screened as recommended, and discuss your risk factors and health history with your doctor as part of an overall healthy-heart plan.