Vitamin E valued in preventing degenerative disease

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Vitamin E loss through smoking increases health risks

15 Apr 2005 Medical News Today

New studies in the Linus ing Institute at Oregon State University

have shown that vitamin E disappears more quickly in smokers than in

non-smokers - findings that may help explain how smoking can cause

cancer.

The research, published in the American Journal of Clinical

Nutrition, was done in a controlled study of a group of smokers and

non-smokers, with diet and most other factors largely the same. By

monitoring " labeled " vitamin E, it was found that the blood plasma

levels of this essential nutrient dropped 13 percent faster among

smokers than among the non-smokers, depleting it much more quickly.

The study also demonstrated in humans an important interactive

relationship between vitamins C and E, showing for the first time how

inadequate levels of vitamin C can cause further and faster depletion

of vitamin E.

Together, these scientists say, the research is providing significant

insight into how smoking might cause cancer, and how the loss of

protective antioxidant vitamins can play a role in this process.

" Cigarette smoke is an oxidant, creating free radicals that are

associated with increased oxidative stress, cell mutations, and can

lead to such diseases as cancer, heart disease and diabetes, " said

Maret Traber, a professor in OSU's Linus ing Institute and a

national expert on vitamin E. " In lung tissue, vitamin E is one of

the first lines of defense against the free radicals generated by

cigarette smoke. "

It has been known for some time that cigarette smoking reduced blood

levels of vitamin C, Traber said, but the data were less clear on

vitamin E - it did not appear that there were significant differences

in the blood plasma levels of vitamin E between smokers and non-

smokers.

But researchers now believe what is happening is that vitamin E is

being depleted from tissue concentrations in order to keep up its

levels in the blood, leaving the tissues - including those of the

lungs - particularly vulnerable to attack by toxins and free

radicals. The new studies support that thesis, say Traber and

Bruno, also an LPI researcher.

" The liver has a protein that helps to regulate blood concentrations

of vitamin E, and while the blood plasma levels may be the same, it

appears the tissues are being depleted, " Bruno said. " Our research

makes it clear that smokers must receive more vitamin E than non-

smokers in order to achieve the same overall levels in the body. If

the blood levels are the same, and vitamin E is leaving the blood

faster, then the tissues must be depleted. "

In simple terms, this may mean that with smokers, their diet may be

normal but they will have increased usage of vitamin E, and they are

at risk of losing its protective effects.

The interaction of vitamin C and E is another part of the puzzle, the

scientists said.

" Both vitamins C and E are antioxidants with related roles, but

vitamin C is water soluble and vitamin E is fat soluble, " Traber

said. " Vitamin C is found outside cell membranes while E is inside

the membranes. "

In practice, the scientists believe that vitamin E often plays the

first role in intervening against free radicals and preventing

membranes from becoming oxidized - but in the process, vitamin E

itself can be made into a radical. If adequate vitamin C is present,

it can help the vitamin E return to non-radical form. But without

adequate levels of vitamin C in the body, vitamin E in tissues can

quickly decline, Traber said.

" We've now shown this interaction among these two antioxidants in the

human body for the first time, an important step forward, " Traber

said. " Smokers with the lowest vitamin C levels have the fastest

disappearance of vitamin E. This is complex biochemistry, but it's

part of our body's natural defense mechanism against toxins. "

Plants, Traber said, will produce more vitamin E to protect

themselves when they are under stress. Humans do not have the ability

to do that, and must obtain the nutrient from their diet. When

certain agents, such as cigarette smoke, place the body in a

condition of constant oxidative stress, the stage can be set for

disease, the researchers believe.

Nearly 50 million Americans smoke cigarettes. And some of the most

common sources of vitamin E in the diet - oils, fats, desserts - have

been steadily reduced in recent years in the move towards low-fat

diets. At least partly as a result, studies show that only 8 percent

of men and 2.4 percent of women in the U.S., regardless of smoking

status, have adequate dietary intake of vitamin E.

For protection, vitamin E must be present before free radical damage

occurs, the OSU researchers say. It cannot be ingested later and

expected to repair all the damage.

" There has been practically a war going on in the science community

for some time now about the value of vitamin E, but much of what gets

lost in the debate is the distinction between preventing a serious

disease and being able to cure it, " Traber said. Some recent studies,

often done with sick or elderly people, were unable to demonstrate a

health benefit from vitamin E supplementation, Traber said. One

recent analysis even concluded that vitamin E might be dangerous.

" Some people have the inaccurate notion that moderate supplementation

with vitamin E will hurt you, and that simply is not true, " Traber

said. " What's increasingly clear is that many people have health

habits, such as smoking or poor diet, which can leave them with

inadequate levels of vitamin E. And vitamin E has clear value in

helping to prevent serious degenerative disease. "