DALLAS, May 26 -- After spending only 30 minutes in a smoke-filled room, participants in a study had losses in their blood stores of antioxidants, including vitamin C, according to a study reported today in an American Heart Association journal.
By depleting the body's stores of antioxidants, secondhand smoke breaks down this valuable defense against heart disease, says the study's lead author, Timo Kuusi, M.D., Ph.D., of the department of medicine, Helsinki University Hospital, Helsinki, Finland.
"An increasing number of reports have documented the harmful effects of environmental tobacco smoke. The present study demonstrates how secondhand smoke could increase the risk of coronary heart disease, a major cause of heart attacks," he says.
Reporting in Circulation: Journal of the American Heart Association, Kuusi and co-author Miia Valkonen, M.D., say that antioxidants neutralize toxic "oxygen-free radicals." These unstable molecules, produced during interactions with oxygen, are found in tobacco smoke. Free-radicals can combine with cholesterol in the blood to make oxidized cholesterol. This is a dangerous form that "sticks" to the inside walls of the blood vessel to form piles of fat, called plaque, that can block the blood vessels or unleash a blood clot, causing a heart attack or stroke.
The researchers measured antioxidants in blood from 10 healthy nonsmoking men and women after they spent 30 minutes in a room full of cigarette smoke. A test, called TRAP (total peroxyl radical trapping potential of serum), measured the capacity of all blood antioxidants to rid the body of free radicals. Passive smoking caused a 31 percent drop in TRAP values.
"We found that a short period of passive smoking changed cholesterol metabolism, favoring progression of atherosclerosis," he says. "The cardiovascular system is extremely sensitive to the chemicals in environmental tobacco smoke.
"The free-radical stress by secondhand smoke may have a more prominent effect on a nonsmoker than an active smoker whose cardiovascular system has a more permanent (oxidant) imbalance. The changes (in antioxidants) that we measure may not be as pronounced."
Whether antioxidants such as vitamin C will help prevent antioxidant depletion from secondhand smoke needs further study, adds Kuusi.