© 2007 American Thoracic Society
On Previous Findings Concerning Preserved Meat Intake and Respiratory DiseaseFrom the Authors:We thank Dr. Butler and colleagues for their letter commenting on our recent article (1). It would have been reasonable to reference their recent article on dietary patterns and persistent cough (2); however, there are considerable differences between the two studies. First, Butler and colleagues studied asthma and "usual cough with phlegm on arising or during the rest of the day" in a predominantly (approximately 72%) never-smoking population (2). Since Medical Research Council-defined chronic bronchitis, emphysema, or chronic obstructive pulmonary disease (COPD) were not reported, and their analyses were not stratified by smoking status, we were less clear if the hypothesis of their study had to do with asthma or COPD. We, on the other hand, were interested in COPD and lung function measures (1). Second, their article was mostly focused on dietary patterns while we examined cured meats based on a strong a priori biological hypothesis. Because there are many potential differences between dietary patterns, the dietary pattern approach may not be very informative about biological relationships between dietary components and outcomes of interest. Therefore, we think that the observed associations should be evaluated in the light of results from individual component analyses. Third, Butler and colleagues' study was conducted among Chinese in Singapore while the NHANES III was conducted in the United States. How meats and fish are preserved in the two countries is very different. Preserved meats and dried salted fish in Asia contain high nitrosamine levels, whereas cured meats in the United States currently have little nitrosamine, but are high in nitrite (a result of changes made by the Food and Drug Administration in the 1970s) (3). It is interesting that Butler and colleagues observed a positive association between nitrosamine intake and incident cough and phlegm, but the association disappeared after further adjustment for the meat–dim sum dietary pattern. It is unclear how correlated the two variables were in their study. If nitrosamine intake and the meat–dim sum dietary pattern were highly correlated, it would be difficult to tease out the independent associations of the two. We were unable to examine the association between nitrosamine intake and lung function and COPD in our article since the NHANES III nutrient database does not include nitrosamine intake. Despite these differences, the two studies appear to support each other in that high consumption of cured/preserved meats was associated with lower lung function characteristic of COPD and incident productive cough in two diverse populations with very different dietary and smoking habits.
College of Physicians and Surgeons, Columbia University, New York, New York
Hankinson Consulting, Valdosta, Georgia
College of Physicians and Surgeons and Mailman School of Public Health, Columbia University, New York, New York FOOTNOTES Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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