From the article:

Bouchier-Hayes and colleagues recruited 15 healthy smokers aged 20 to 37 and 15 healthy non-smoking volunteers. The smokers were given either two grams per day of vitamin C for five days or 1.5 grams per day of taurine.

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The researchers report that taurine restored normal vessel function according to [flow mediated dilation (FMD)] measurements. At baseline, non-smokers' blood vessel diameter was 3.39 mm and smokers' diameter was 3.33. Before treatment, FMD increased dilation in non-smokers to 3.7 mm, while smokers' vessels were virtually unchanged at 3.36 mm after FMD. When they took vitamin C, smokers' vessel diameter increased to 3.45 mm after FMD. When the were given taurine, the smokers' vessel response was the same as the non-smokers' at 3.7 mm after FMD.