A dose of vitamin C may give a quick boost to the poorer-than-average blood circulation seen in relatively healthy young smokers, a Japanese study suggests.
The study of 25 healthy men found that although smokers initially showed poor results on a test of blood flow to the heart, that changed after they took 2 grams of vitamin C.
Shortly after taking the vitamin, the 13 smokers showed blood circulation on par with that of the non-smokers.
Vitamin C is a potent antioxidant, a substance that helps clear the body of damaging molecules called oxygen free radicals. It's thought that the vitamin may counter the "oxidative stress" that smoking puts on the lining of the blood vessels, a mechanism by which smoking leads to artery disease.
The new study looked at the effect of oral vitamin C on coronary flow velocity reserve (CFVR), a measure of how well blood flow speeds up to help the heart when it's under high demand. Past research has shown that smokers show poorer blood-vessel dilation in response to blood flow, and have a diminished CFVR.
Researchers found that before taking the vitamin, smokers had a lower CFVR than non-smokers did. Two and four hours after the dose of vitamin C, however, smokers' average CFVR was restored to a more normal level.
Though the men in the study were given a large dose of vitamin C, the researchers point out that it's probably useless to take doses beyond 200 milligrams, because the body will excrete the excess.
Moreover, it's not clear that loading up on vitamin C can benefit smokers. Some trials have found that taking C supplements does not improve smokers' blood vessel function, at least in the short term. Large-scale trials should look at whether daily vitamin C supplements cut smokers' long-term risk of coronary artery disease.
The researchers say their findings underline the dangers of smoking. The findings, out of Chiba University Graduate School of Medicine, are reported in the American Heart Journal.
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