15 April 2005
Smoking, Cancer Link May Be Related To Vitamin E Loss
Researchers at the Linus Pauling Institute at Oregon State University (OSU) have found that vitamin E disappears more quickly in smokers than in non-smokers. They believe these findings may help explain how smoking causes cancer. Studying a group of smokers and non-smokers whose diets were largely the same, it was found that the blood plasma levels of vitamin E dropped 13 percent faster in smokers. The study, appearing in the American Journal of Clinical Nutrition, also demonstrated an important relationship between vitamins C and E, showing how inadequate levels of vitamin C can cause further and faster depletion of vitamin E.
"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, at OSU. "In lung tissue, vitamin E is one of the first lines of defense against the free radicals generated by cigarette smoke." Traber said that while it had been known that cigarette smoking reduced blood levels of vitamin C, the data were less clear on vitamin E. But researchers now believe 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.
"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," said co-researcher Richard Bruno. 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 researchers said that the interaction of vitamin C and E was another part of the puzzle. "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." 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. "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," Traber said.
Traber questions some recent studies which were unable to demonstrate a health benefit from vitamin E supplementation, or even suggested 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. 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," he concluded.