Frequent consumption of cured meats results in lower lung function test scores and increases the odds of developing chronic obstructive pulmonary disease (COPD), according to a large cross-sectional survey of adults in the U.S.
The study results appear in the second issue for April 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
Rui Jiang, M.D., Dr.P.H., of Columbia University Medical Center in New York, and three associates showed that the "odds ratio" for developing COPD among individuals who consumed cured meat products 14 times or more per month was 1.93, as compared with those who did not consume cured meats. An odds ratio greater than 1 implies that the event is more likely to occur within that group.
"Cured meats, such as bacon, sausage, luncheon meats and cured hams, are high in nitrites, which are added to meat products as a preservative, an anti-microbial agent, and a color fixative," said Dr. Jiang. "Nitrates generate reactive nitrogen species that may cause damage to the lungs, producing structural changes resembling emphysema."
Although certain rodent studies suggest that inhalation of nitrogen dioxide may contribute to emphysema, no other human studies to date have examined the relationship between consumption of cured meats and COPD, which is the fourth leading cause of death in the U.S.
In 2004, more than 11 million U.S. adults were estimated to suffer from COPD, which results from chronic bronchitis and emphysema, two inflammatory lung diseases that frequently co-exist and interfere with breathing.
The study cohort consisted of 7,352 individuals who participated in the Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994 by the National Center for Health Statistics. The average age of participants was 64.5 years, and 48 percent were male.
"Individuals who consumed cured meats frequently were more likely to be male, of lower socioeconomic status, to be tobacco users, and were less likely to report physician-diagnosed asthma than individuals who never consumed cured meats," said Dr. Jiang. "Those who consumed cured meats more frequently had lower intakes of vitamin C, beta-carotene, fish, fruits, vegetables, and vitamin or mineral supplements. They also had higher intakes of vitamin E and total energy."
The hazard ratio from cured meats associated with lower lung function test results and increased odds for COPD did not change after researchers made adjustments for multiple dietary and other risk factors.
"Adjustment for these factors in our analyses did not appreciably change our findings, suggesting that the observed association between cured meats and lung function was unlikely to be explained by potential dietary confounding factors reported in previous studies," said Dr. Jiang.
The researchers noted that high dietary nitrite intake warrants further evaluation in prospective longitudinal studies as a novel risk factor for COPD.