UA College of Public Health Study Indicates Antioxidants May Lessen
Harmful Effects of Sidestream Cigarette Smoke
Nov. 13, 2001
From: Vicki B. Gaubeca, (520) 626-7301
A new study at the University of Arizona College of Public Health provides evidence that multiple antioxidants may help lessen the harmful effects of sidestream cigarette smoke. (Sidestream smoke, which is considered more toxic, is direct cigarette smoke, not second-hand smoke that already has been inhaled and exhaled.)
Dietary antioxidants have long been promoted as a defense against many diseases, among them cancer, cardiovascular disease, and diseases of the immune system. This study for the first time explores cellular responses to sidestream cigarette smoke in aged mice and whether antioxidants lessen negative effects.
"The research found that exposure to moderate levels of sidestream cigarette smoke increased harmful oxidation and also promoted the production of interleukin-6, a substance closely linked to cardiovascular disease," explains Ronald R. Watson, PhD, principal investigator and professor at the UA College of Public Health. "But the study also showed that multiple antioxidants given as dietary supplements prevented these changes."
Cigarette smoke does much of its damage via "free radicals" (highly reactive and usually short-lived molecular fragments with one or more unpaired electrons) in the form of reactive oxygen species (oxygen-containing radicals responsible for bacterial killing as well as incidental damage to surrounding tissue), which can overwhelm the cell's antioxidant defenses. These species also can start the cellular chain reaction that leads to inflammation. Tobacco smoke not only is among the greatest external sources of free radicals it also works internally, causing the body to produce reactive oxygen species that may increase damage inside cells.
Based on earlier studies, investigators hoped to find that multiple antioxidants, rather than a single one, may help prevent the damaging oxidation and inflammation caused by sidestream smoke. The mice were fed 11 antioxidants: beta carotene, bioflavonoids, coenzyme Q10, d-alpha tocopherol, L-ascorbic acid, L-carnitine, magnesium, N-acetylcystein, retinol, selenium and zinc. The researchers looked at three cellular defense mechanisms-hepatic lipid peroxide, vitamin E level and interleukin-6 production-in both "nonsmoking" and "smoking" mice.
They found that in healthy, old mice (13 months at the start of the study), exposure to a burning cigarette for 30 minutes a day, five days a week, for four months, increased the production of interleukin-6 in the spleen and lipid peroxide in the liver. Lipid peroxide results when a cell's antioxidant defenses are overwhelmed by reactive oxygen species. Interleukin-6 is a protein produced as an immune response to inflammation. The study also found that in smoke-exposed mice, vitamin E, itself a powerful antioxidant, was depleted.
Dietary multiple antioxidants turned these effects around. For both "smoking" and "nonsmoking" mice fed antioxidant supplements, lipid peroxide production was significantly lower, while vitamin E levels were significantly higher. In addition, smoke-exposed mice fed antioxidant supplements showed significantly lower production of interleukin-6 compared to smoke-exposed mice on a control diet.
Dr. Watson emphasizes that "an ounce of prevention is worth a pound of cure. Clearly reducing exposure by removing smoking from restaurants or in the home is much more protective than taking some vitamins."
Researchers hope that multiple antioxidants may similarly benefit humans. Other study investigators were Zhang Jin, BS, and Shugang Jiang, MD, PhD, both researchers at the UA College of Public Health.
Established by the Arizona Board of Regents in January 2000, the Arizona College of Public Health is the first public health college in the southwestern United States and represents a tri-university collaborative effort with Arizona State University and Northern Arizona University. The College of Public Health's mission is to promote the health of individuals and communities with a special emphasis on diverse populations and the Southwest. Programs concentrate on the reduction of health disparities, the development and maintenance of healthy communities, and the promotion of healthy lifestyles.