Another chief factor is having high cholesterol, particularly when it’s coupled with other issues like high blood pressure, diabetes, and, yes, smoking. Having more than one risk factor acts like a “double whammy” on your body, says Nitin Damle, MD, an internal medicine physician in Wakefield, Rhode Island, and president of the American College of Physicians. “The risk is already significant for smokers who don’t have high cholesterol, and it increases significantly if they have a high lipid [cholesterol and triglycerides] profile, they smoke, are male, or have diabetes,” says Dr. Damle. “When you combine these factors, the risk increases exponentially.” Here’s what you need to know about the link between smoking, cholesterol, and heart disease.

Smoking and Your Heart Attack Risk

The most well-documented impact that smoking has on cholesterol is how it lowers levels of high-density lipoprotein (HDL). HDL has protective effects against heart disease; it’s particularly beneficial for women, who typically have higher levels of the cholesterol than men. Because smoking lowers the concentration of HDL, any benefits women might have are erased if they smoke. No conclusive research has shown that smoking alters levels of low-density lipoprotein (LDL), but smoking does worsen the detrimental effects that LDL naturally has on the body, says L. Kristin Newby, MD, professor of medicine at the Duke University School of Medicine in Durham, North Carolina. “Smoking creates an environment in the bloodstream that leads to a destructive breakdown [of cholesterol], making LDL even more toxic to blood vessels, increasing deposits of plaque in the arteries, and increasing inflammation,” Dr. Newby says. This chronic inflammation of the blood vessels and buildup of fatty plaques is called atherosclerosis. Plaque restricts blood flow throughout the body; after years of growth, plaques can burst and create a blood clot, which reduces or blocks blood flow to the heart, causing a heart attack. Blood clots can also travel throughout the body, causing a stroke if blood flow to the brain is blocked.

How to Reverse Smoking’s Damage to Your Heart

Being a smoker and having high cholesterol is clearly a bad combination, but the good news is that quitting can make a big difference — and fast. Stopping smoking yields immediate and long-term benefits for your cholesterol levels, and lowers your risk for having a heart attack. A review of studies published in September 2013 in the journal Biomarker Research found that HDL levels can increase by as much as 30 percent within just three weeks of stopping smoking. Newby says that when you quit, smoking’s detrimental effects on your blood pressure and platelets will correct very quickly. In addition, your heart attack risk drops by an estimated 30 percent within a year of quitting. “Five to 10 years after you quit, your risk of heart attack is almost the same as if you had never smoked,” she says. This reversal occurs regardless of whether you smoked for one year or 30 years. And often, kicking the habit creates a pathway to not only improving cholesterol, but also to building a healthier lifestyle overall, Damle says. “Not smoking improves lung function, and as you do that, you can engage in good health habits like increasing exercise,” which also helps lower your cholesterol, he says. “It’s part of a lifestyle change people need to make, including getting physically active and eating the right kinds of foods.” To estimate your risk of having a heart attack, the National Heart, Lung, and Blood Institute offers an online assessment tool. Smoking and cholesterol levels are two main measures used to gauge your heart attack risk, along with your age, gender, and blood pressure. If you smoke and want to quit, talk to your doctor about smoking cessation options, and visit the Everyday Health guide to quitting smoking for more information.