A dose of vitamin C may give a quick boost to the poorer-than-average blood circulation seen in healthy young smokers, a study suggests.
The study of 25 healthy men found that although smokers initially showed poorer results on a test of blood flow to the heart that changed after they took a large dose — 2 grams — of vitamin C.
Shortly after taking the vitami! n, the 13 smokers showed blood circulation on par with that of the 12 non-smokers, according to findings published in a leading heart journal.
However, lest smokers think they can undo heart damage by chasing a cigarette with a vitamin C pill, the researchers say their findings underline the dangers of smoking.
Vitamin C is a potent antioxidant, a substance that helps clear the body of cell-damaging molecules called oxygen free radicals. Because of this, 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 res! erve (CFVR), a measure of how well blood flow speeds up to hel! p the he art when it's under high demands. Past research has shown that smokers show poorer blood-vessel dilation in response to blood flow, and have a diminished CFVR.
The research team used a non-invasive ultrasound technique to measure CFVR in smokers and non-smokers, before and after they took vitamin C.
They 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, researchers pointed out that it's probably useless to take doses beyond 200 milligrams, because the body will excrete the excess.
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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.
Researchers said further, large-scale trials should look at whether daily vitamin C supplements cut smokers' long-term risk of coronary artery disease.
By Tanya Roberts
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