Taurine Proves Heart-Worthy in Smokers

DUBLIN, Ireland--New research highlighted the semi-essential amino acid, taurine, as a possible deterrent of cigarette smoke-induced endothelial dysfunction, a precursor to atherosclerosis. Appearing in the Jan. 6 rapid access issue of Circulation: Journal of the American Heart Association [AHA] (www.circulationaha.org), the study indicated that taurine supplementation worked even better than vitamin C in improving impaired flow-mediated dilation (FMD), an effect that may be due to chronic cigarette smoking impairing the activity of endothelial-derived nitric oxide.

Lead author David Bouchier-Hayes, M.D., and colleagues from the Royal College of Surgeons in Dublin, Ireland, noted nitric oxide activity is critical in many heart-health processes, including platelet aggregation, vascular smooth muscle proliferation and oxidative modification of LDL cholesterol. FMD, a nitric oxide-mediated response, has been shown to appear in the brachial arteries of young, otherwise healthy, cigarette smokers, according to the study's researchers.

"When blood vessels are exposed to cigarette smoke, it causes the vessels to behave like a rigid pipe rather than a flexible tube," Bouchier-Hayes stated in an AHA press release, "thus the vessels can't dilate in response to increased blood flow. We're not trying to find a therapeutic treatment for smoking, because we believe the best therapy for smokers is to stop smoking. Nonetheless, smokers provide a good clinical model for treatment of endothelial dysfunction."

The study involved 15 healthy smokers (20 to 37 years old who smoked at least two packs per day) and 15 nonsmokers (21 to 35 years old). All volunteers were normotensive and had no history of hyperlipidemia. For five days, smokers were given 2 g/d of vitamin C (supplied by Basel, Switzerland-based Roche Pharmaceuticals), followed by a two-week washout period, and were then given 1.5 g/d of taurine (provided by Hauppauge, N.Y.-based Twinlab).

Using duplex ultrasonography, researchers assessed the effect of FMD on brachial artery diameter at baseline in both nonsmokers and smokers, with FMD significantly impaired in the latter. Vitamin C supplementation had a significant effect on the smokers' FMD, with arterial diameter increasing approximately .12 mm; however, FMD was not restored to the level seen in the nonsmoking control group. Conversely, taurine supplementation was found to not only increase arterial diameter approximately .37 mm, but FMD was restored to levels found in the control group.

The researchers reported that taurine, which appears to be nontoxic, already is used clinically in similar or greater daily doses in patients with diabetes mellitus and congestive heart failure. Also, in a worldwide epidemiological study on dietary prevention and cardiovascular disease (the Cardiovascular Diseases and Alimentary Comparison Study), 100 g/d of fish was found to reduce the risk of coronary artery disease at the same level as seen in the Japanese population. "The dose of taurine used in the present study is equivalent to that found in 100 g of fresh fish," Bouchier-Hayes et al noted.