Vitamin C Supplements Can Largely Stop The Depletion Of Vitamin E That Occurs In

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Vitamin C Supplements Can Largely Stop The Depletion Of Vitamin E

That Occurs In Smokers, Study Shows

http://www.medicalnewstoday.com/medicalnews.php?newsid=37878

A new study has found that supplements of vitamin C can largely stop

the serious depletion of vitamin E that occurs in smokers,

demonstrating for the first time in humans a remarkable interaction

between these two antioxidants as they work together.

The research also suggests a possible mechanism by which smoking can

cause cancer.

The findings are being published today in Free Radical Biology and

Medicine, a professional journal, by scientists from the Linus

ing Institute at Oregon State University.

The results of the research were based on a placebo-controlled,

double-blind clinical study with smokers and non-smokers, and showed

that supplements of 1000 milligrams of vitamin C per day could reduce

by up to 45 percent the rate of disappearance of one form of vitamin

E in smokers. In general, vitamin C supplements helped protect the

function and plasma levels of vitamin E, so that smokers who took

supplements had about the same level of antioxidant protection as non-

smokers.

" A lot of nutrition research in the past has been done by studying

one nutrient or another in isolation, sometimes with conflicting

results, " said Maret Traber, a professor of nutrition at OSU and lead

researcher in the Linus ing Institute. " What this and other

studies like it are showing is that the protection we get from proper

diet or supplements often comes from combinations of nutrients

working together. This has implications not only for smokers but also

for many other people. "

Vitamin E is one of the first lines of defense in human lung tissue

against the ravages of cigarette smoke, Traber said, which creates

destructive free radicals. If the body has adequate levels of vitamin

E, this protective antioxidant can interact with the peroxyl radicals

created by cigarette smoke and prevent the destruction of lung

membranes.

In this process, however, vitamin E can itself be made into a

destructive radical. If adequate levels of vitamin C are present, it

can help the vitamin E return to non-radical form and continue its

protective role. But in the absence of adequate vitamin C, this

process breaks down. The new study is one of the first to ever

demonstrate this phenomenon in humans.

This and other studies at the Linus ing Institute have also shown

that in smokers, vitamin E is being depleted from tissue

concentrations in order to keep up its levels in the blood.

" We've known for some time that smokers are under oxidative stress,

because the smoke itself is an oxidant that creates free radicals and

cell mutations, " Traber said. " The immune response of the body also

tends to cause inflammation, and this inflammation is one reason that

smoking relates not only to lung cancer but other serious health

problems such as diabetes, hypertension and heart disease. "

By having a more rapid loss of protective antioxidants, Traber said,

smokers face special challenges.

" Think of a bucket that's filled with water but has holes in it, " she

said. " If you want to keep the water level, you have to keep adding

water. But with smokers, the holes in the bucket are bigger and the

water level goes down faster. In the case of nutrition, you have to

add more and more nutrients to stay even. "

With smokers, she said, that rarely happens. In the general

population, research has shown that only 8 percent of men and 2.4

percent of women have adequate dietary intake of vitamin E. And

studies indicate that smokers often have a diet with lots of meat but

low intakes of the fruits and vegetables that provide most

antioxidants. So although smokers require higher levels of

antioxidants to gain their protective benefits, their diets usually

contain even lower dietary intakes than most people - and nearly 50

million Americans smoke cigarettes.

For antioxidant vitamins to play a role in disease prevention,

experts say, they usually have to be present in advance. They are

less successful in addressing existing disease. According to Traber,

many of the studies showing " no benefit " from improved nutrition or

vitamin supplements have been done in people with existing disease,

or studying one nutrient at a time rather than combinations.

In this research, participants were asked to eat a diet low in fruits

and vegetables for three months so they had low levels of vitamin C.

Some members were then given vitamin C supplements, and others a

placebo. Smokers who got vitamin C supplementation had a plasma

vitamin E disappearance rate about the same as non-smokers. But

smokers who were still deficient in vitamin C lost alpha vitamin E

about 25 percent faster than non-smokers, and gamma vitamin E about

45 percent faster.

Other collaborators on this research were from Columbia University,

The Ohio State University, the University of Washington, and Brock

University in Canada. Bruno, a doctoral student at The Ohio

State University, was also a co-author. The research was funded by

the National Institutes of Health.

" What this clearly shows is that to perform their vital roles,

vitamins C and E work together, " Traber said. " They have a

synergistic effect that will not be gained just by intake of one or

the other, and adequate levels of these nutrients is especially

important for people who smoke. "