Vitamin C Isn't a Smoker's Salvation
May 23, 2000 -- People taking vitamin C to cancel out the health
consequences of smoking should take note. Although some previous studies have
shown that injections of vitamin C can improve smoking-related damage of the
blood vessels, a new study in the May issue of the Journal of the American
College of Cardiology suggests that extra vitamin C has no real benefits
Because smoking is known to cause damage to blood vessels that can lead to
heart disease and stroke, scientists have looked for ways to prevent that
damage, or possibly reverse it. Research has shown that levels of vitamin C are
generally lower than normal in the blood of smokers. Vitamin C, like many other
vitamins, is an antioxidant, and may have beneficial effects on the heart and
It has been suggested that boosting the blood levels of vitamin C might
improve function in blood vessels that have been damaged by years of smoking.
Indeed, some studies have shown that injections of high doses of vitamin C can
reduce the damage to some extent but have shown no evidence that long-term
damage to the blood vessels can actually be reversed. Researchers who conducted
those studies always questioned whether the good results seen with the vitamin
C injections could be gained by taking vitamin C tablets.
The new study seems to validate those concerns. In addition, whatever
benefits vitamin C may initially have do not persist over time, writes lead
author Olli Raitakari, MD, PhD, of the Royal Prince Alfred Hospital in
The study of eight male and 12 female smokers with an average age of 36
found that a single high dose of vitamin C taken by mouth significantly
increased the amount of vitamin C in the bloodstream and improved blood flow in
a main blood vessel in the upper arm. But Raitakari and colleagues found that
daily ingestion of the vitamin at half that dose for eight weeks resulted in no
significant or sustained benefit, even though levels of the vitamin remained
high in the bloodstream.
How smoking causes damage to the arteries is unclear. What is known is that
smoking increases the amount of "free radicals" in the blood, which
occur naturally in everyone but are highly destructive. Free radicals can
change or damage the lining of the walls of blood vessels. Antioxidant vitamins
such as vitamin C and vitamin E are thought to help out by "mopping up"
the free radicals in the blood and limiting the amount of damage they can
cause. But smoking causes many other changes as well, making it hard for
researchers to pinpoint a single reason behind smoking's harmful effects.
One expert who reviewed the study said smokers should not jump to the
conclusion that taking vitamin C daily is of no use to them.