They found that the additional blood supply that should be available to the heart during stress was reduced by 21 percent in smokers compared with the non-smokers. Individuals in the study did not have symptoms of heart disease. The mechanisms by which smoking damages the coronary system is not fully understood but the researchers say their findings support the hypothesis that free radicals, or unstable oxygen molecules, in cigarette smoke may be responsible. The proof is that when individuals were given an antioxidant like vitamin C, the blood flow was restored. In the study, researchers administered vitamin C intravenously to normalize blood flow in smokers.
Smoking cigarettes is known to deplete levels of vitamin C and other antioxidants.
They note that the greater amount of vitamin C in the Mediterranean diet could be one reason why there is not more heart disease in the Mediterranean region despite a higher prevalence of smoking there.