The list of the harmful effects of smoking continues to grow. In addition to cancer of the lungs and throat, smoking has been linked to emphysema and various cardiovascular diseases. Smoking can cause spikes in heart rate and blood pressure, which puts strain on the heart. Smoking also slows blood flow, especially to the hands and feet. An important, often misunderstood, factor of cardiovascular health that is affected by smoking is the role of cholesterol.
The Function of HDL
HDL, or high density lipoproteins, are commonly called the good cholesterol. Lipids, such as cholesterol, cannot travel freely through the bloodstream and would simply collect in the blood vessels. To transport these lipids, they are encapsulated by proteins and carried to where they are needed. HDL absorbs excess cholesterol from the blood vessels and carries it to the liver where it can be broken down and expelled.
How Smoking Decreases HDL
The exact mechanism for the effects of smoking on HDL levels is unclear. Exercise increases HDL production and because smoking lowers respiratory efficiency, making exercise more difficult, it has been theorized that this leads to a decrease in HDL levels. Cigarette smoke also contains multiple toxins that interfere with proper cholesterol balance. Acrolein is a toxin chemical released when tobacco is burned that increases LDL levels. Acrolein also prevents HDL from functioning properly.
Effects
Decreased HDL levels can lead to formation of plaque along the blood vessels, which is generally prevented by the janitorial function of HDL. Excess plaque can cause a hardening of the walls of the arteries, called atherosclerosis. The symptoms of atherosclerosis can vary widely depending on which artery is effected.
Expert Insight
A study published in the journal "Atherosclerosis" examined the effects of smoking on HDL levels. The researchers wrote that "Cigarette smoking was found to be associated with an average difference in HDL cholesterol of about 4 mg/dl in men and 6 mg/dl in women." These results show a definite link between smoking and HDL levels, as well as general cardiovascular health.
Prevention/Solution
Giving up tobacco will likely result in a return healthy HDL levels. Exercise and a diet low in trans fat and high in fiber can also contribute to restoring HDL levels. Omega-3 fatty acids may beneficial in increasing HDL.
