- The risk of heart disease is higher in those who smoke cigarettes over a long period of time.
- Carbon monoxide in the cigarette smoke deoxygenates blood, encourages plaque formation on arteries, over time.
Relative risk of heart disease is higher for smokers consuming cigarettes over a longer period of time than for smokers consuming the same quantity over a shorter period.Increased relative risks for coronary heart disease (CHD) have long been associated with smoking, and traditionally they have been dependent on the number of cigarettes smoked a day, smoking intensities, and total exposure over time.
Researchers found the risk is higher for smokers with longer exposure to cigarettes after observing data from nearly 120,000 participants over 27 years. The longevity of exposure impacts CHD risk - a relationship described by researchers as the "delivery rate effect."
‘An individual who smoked 20 cigarettes a day for 50 years has a higher relative risk of heart disease than someone who smoked 50 cigarettes a day for 20 years.’
"We now have observed inverse smoking intensity effects in multiple cohorts with differing smoking patterns and other characteristics, suggesting a common underlying phenomenon," says lead author Jay H. Lubin, PhD, with the U.S. National Cancer Institute at the National Institutes of Health.
Smoking accelerates the hardening and narrowing process in the arteries. It decreases HDL (good) cholesterol which help in transporting the excess fat in the blood to the liver for storage. Nicotine in the cigarette causes constriction of blood vessels which increases blood pressure resulting in hypertension. Also, smoking cigarettes increases the duration of ischemia, the inadequacy of blood supply to the heart muscles.
Acknowledging that cigarette smoking has both long-term and short-term effects on CHD, these findings suggest the long-term effects of smoking have an increased consequence. The relationship to CHD risk from smoking for a longer duration also appears to be a more widespread phenomenon than previously thought.
- Jay H. Lubin et al., New study highlights smoking intensity in coronary heart disease risk, Nicotine and Tobacco Research (2016),