If the surgeon general's warning that cigarettes cause lung cancer, heart disease, emphysema and pregnancy complications isn't enough of a deterrent, smoking also can trigger chronic diseases by depleting the body's levels of vitamins E and C and increasing oxidative stress, according to researchers in the Linus Pauling Institute at Oregon State University.

In a study recently published in the American Journal of Clinical Nutrition, OSU scientists demonstrated for the first time in humans that low levels of vitamin C correlate strongly with accelerated vitamin E loss in smokers.

Understanding the process and implications of the research requires a quick science lesson, explained Richard Bruno, research associate in the Linus Pauling Institute and lead investigator of this study.

Free radicals are highly reactive chemical compounds that can damage cells. Scientists believe damage to cellular components such as proteins and DNA can trigger illnesses, including cancer.

Antioxidants, such as vitamins E and C, combat free radicals. When free radicals outnumber antioxidants, oxidative stress occurs.

Bruno and Maret Traber, professors in the nutrition and exercise sciences department and Linus Pauling Institute and principal investigators on this study, knew from previous research that smokers have reduced levels of vitamin C.

Along with another OSU investigator and two scientists from other universities, they decided to examine the effects of cigarette smoke on vitamin E, and whether smoking increases the amount of vitamins E and C the body needs to fight free radicals and prevent oxidative stress.

"We found that smokers have a one-two punch," Bruno said. "They get the first hit of free radicals from the smoke they inhale from cigarettes. The second hit comes from the white blood cells, which activate and release free radicals to fight the smoke, which the body perceives as a foreign invader in the lungs."

During their clinical trial, Bruno and Traber studied 10 smokers and 10 non-smokers for six days. Each subject received 150 milligrams of "marked" vitamin E. This synthetically created supplement enabled the researchers to track the vitamin E and differentiate between it and vitamin E the subjects got in their diets.

The investigators took blood samples throughout the week and during the three weeks after they stopped administering the marked vitamin E. They watched the rate at which the vitamin E disappeared from the plasma in blood of the two experimental groups.

Vitamin E levels dropped 13 percent faster among the smokers than the non-smokers, Traber reported.

And smokers who had the lowest levels of vitamin C had the fastest disappearance of vitamin E, she added.

Oxidized vitamin E, a fat-soluble nutrient, is no longer effective as an anti-oxidant. However, vitamin C, a water-soluble nutrient, can restore oxidized vitamin E to its non-oxidized state, Bruno explained. That offers a possible explanation of why smoking decreases blood levels of vitamin C — because the vitamin C is being used to normalize vitamin E oxidized by smoking.

"I think it's a great addition to the scientific literature, showing that vitamin E is an anti-oxidant in the body. It shows that smokers do need more vitamin E and C than non-smokers in their diets," said Bruno.

Traber recommends taking a vitamin E supplement or a multi-vitamin, since fewer than 5 percent of Americans consume the recommended 15 milligrams of vitamin E per day.

The upper safety limit for vitamin E is 1,000 milligrams per day, she added.

Both Bruno and Traber stressed that while smokers do need more vitamin E and C than non-smokers, the solution is to stop smoking, not reach for dietary supplements.

Traber received a five-year, over $1.2 million grant from the National Institutes of Health six years ago to fund this study.

The researchers are studying whether giving vitamin C supplements to smokers normalizes their levels of vitamin E and reduces their oxidative stress. Traber expects to see results from this investigation in the next several months.