“When blood vessels are exposed to cigarette smoke it causes the vessels to behave like a rigid pipe rather than a flexible tube, thus the vessels can’t dilate in response to increased blood flow,” said David J. Bouchier-Hayes, M.D., senior author of the study, in his description of smoking-related endothelial dysfunction. Such dysfunction is considered one of the earliest signs of atherosclerosis.

“We’re not trying to find a therapeutic treatment for smoking because we believe that the best therapy for smokers is to stop smoking,” added Bouchier-Hayes. “Nonetheless, smokers provide a good clinical model for treatment of endothelial dysfunction.”

Investigators recruited 15 healthy smokers aged 20 to 37 years and 15 healthy non-smoking volunteers. The smokers were given either 2.0 grams daily of vitamin C for 5 days or 1.5 grams daily of taurine. Smokers then waited for a 2-week washout period and switched therapies for 5 more days.

Researchers assessed endothelial function with use of flow mediated dilation, in which ultrasound imaging is used to measure vessel diameter after tourniquet placement. Greater diameter after tourniquet release indicates good endothelial function. In the current study, subjects’ had testing at baseline and after 5 days of both types of dietary supplementation.

Use of taurine restored normal vessel function according to vessel dilation measurement. Baseline non-smokers’ average blood vessel diameter was 3.39 mm and smokers’ average diameter was 3.33 mm; flow testing increased dilation in non-smokers to 3.7 mm, whereas smokers’ vessels were virtually unchanged at 3.36 mm. After the 5 days of taurine supplementation, smokers’ average diameter after testing matched that of the non-smokers --- 3.7 mm.

Vitamin C produced a similar, but smaller response: After supplementation, smokers’ average vessel diameter increased from 3.36 mm to 3.45 mm.

Taurine is found in many foods but is most abundant in fish, said Bouchier-Hayes. The taurine supplement used in the study is equivalent to that found in one serving of fish.

Sidney Smith, M.D., past president of the American Heart Association, said that the study findings provide “further evidence of the damaging effect cigarette smoking has on blood vessels. They may also provide insight into the mechanism by which smoking causes injury to blood vessels. This and other evidence further emphasizes the importance of not smoking if one is to avoid the risk of heart attack or stroke.”