The Link Between Smoking and Atherosclerosis, or Heart Disease

Atherosclerosis is a life-threatening disease in which cholesterol, cellular waste, calcium, and other fatty substances are deposited along the lining of artery walls in your body. These sticky, yellowish deposits, known as plaque, build up over time, hindering your blood flow. If you smoke, you face an increased risk of atherosclerosis, heart attack, and stroke.

Also known as hardening of the arteries, atherosclerosis often starts early in life and progresses slowly as you age. Atherosclerosis typically affects medium and large arteries in the body.

Many scientists believe that damage to the endothelium, the innermost layer of the artery, is where atherosclerosis begins. Damage to the endothelium allows plaque to build up along the lining of your arterial walls, and as it does, blood flow is constricted and the supply of oxygen to your body is decreased.

Plaque can rupture and cause blood clots (thrombus). These blood clots can break away and enter your bloodstream, lodging in another part of your body, sometimes completely blocking blood flow, called an embolus.

Fatty embolisms that block blood flow to your heart cause a heart attack. If they block blood flow to your brain, they cause a stroke. If blood flow to your arms and legs is reduced, it can cause you to have difficulty walking and eventually lead to gangrene.

There are three proven causes of atherosclerosis, including:

Elevated levels of cholesterol and triglycerides in your blood cause damage to your endothelium. Some cholesterol is necessary, and your body usually produces most of what it needs in your liver. The other source of cholesterol comes from animal fat and is known as LDL or "bad" cholesterol.

While our bodies need some LDL cholesterol, too much of it can raise your cholesterol levels dangerously and put you at risk for atherosclerosis and/or a heart attack. Foods that come from animals, such as chicken, eggs, dairy products, beef, and pork, contain cholesterol. Foods from plants do not contain cholesterol.

Blood pressure is the result of two forces. One is the pressure created by your heart pumping blood through your circulatory system. The other is the force of the resistance of the arteries as your blood flows through them. When your heart pumps, it pushes blood through the larger arteries and on into the smaller blood vessels, called arterioles.

The arterioles can constrict or expand, and when they do, the resistance of the blood flow is affected. The more difficult it is for the blood to flow, the higher your blood pressure will be. When high blood pressure goes untreated for a long time and your heart is forced to pump harder to get the blood to flow, the result is often an enlarged and weakened heart muscle.

High blood pressure hurts your arteries and arterioles over time as well. They become scarred and hardened, putting you at risk for atherosclerosis.

Cigarette smoke aggravates both of the above risk factors for atherosclerosis in the following ways:

• Cholesterol: The toxins in tobacco smoke lower your high-density lipoprotein cholesterol (HDL or "good" cholesterol) while raising levels of low-density lipoprotein cholesterol (LDL or "bad" cholesterol).
• Nicotine and carbon monoxide: The nicotine and carbon monoxide in cigarette smoke damage your endothelium, setting the stage for the build-up of plaque.
• High blood pressure: While cigarette smoking won't cause high blood pressure, if you smoke and you also have hypertension, smoking can increase the risk of malignant hypertension, a dangerous form of high blood pressure. Smoking is hard on the heart.

If you're a smoker and you're thinking about quitting, remember, it's never too late to quit smoking. Regardless of your age or how many years you've smoked, research has shown that your body will begin the healing process within 20 minutes of your last cigarette.

Within one year of quitting smoking, your risk for coronary artery disease drops to half that of a smoker. Between 5 and 15 years of quitting, your coronary disease and stroke risk drop to that of nonsmokers.