The study sample included 7,352 NHANES III participants 45 years of age or older with adequate information on meat consumption and lung function. The mean age was 64.5 years and 48.0% were male. Those excluded because of missing measures of cured meat, fish, fruit and vegetable consumption, or lung function were older (mean age = 71.0 yr) and had a higher prevalence of physician-diagnosed emphysema or chronic bronchitis (12.8 vs. 9.54% in the study sample). The distributions of sex, race/ethnicity, and smoking status were similar between the two groups. Those missing lung function data had cured meat consumption similar to participants in the study sample.
The study sample represented 68.2 million adults aged 45 years or older in the United States. The characteristics of this population, stratified by frequency of cured meat consumption are shown in . Individuals who consumed cured meats frequently were more likely to be male, of lower socioeconomic status, and tobacco users, and were less likely to report physician-diagnosed asthma than individuals who never consumed cured meats. Those who consumed cured meats more frequently had lower intakes of vitamin C, β-carotene, fish, fruits, vegetables, and vitamin or mineral supplements; had higher intakes of vitamin E and total calories; and had lower serum levels of vitamin C and E and β-carotene. The distributions of age, body mass index, and total:high-density lipoprotein cholesterol ratio were similar across categories of cured meat consumption.
TABLE 1. CHARACTERISTICS OF U.S. POPULATION (AGE 45 YR) ACCORDING TO FREQUENCY OF CURED MEAT CONSUMPTION (BACON/SAUSAGE/PROCESSED MEATS)
Greater frequency of cured meat consumption was associated with lower FEV1, FVC, and FEV1/FVC after adjustment for demographics and height (, model 1). After controlling for smoking status, pack-years, cotinine levels, and household environmental tobacco smoke (ETS) exposure, these inverse associations were attenuated, but remained statistically significant (, model 2). After simultaneous adjustment for multiple additional confounding variables, individuals who ate cured meat consumption 14 times/month or more had a significantly lower FEV1 (−110 ml; p for trend < 0.001) and FEV1/FVC (−2.13%; p for trend < 0.001) compared with those who never ate cured meats. FVC did not differ significantly across categories of cured meat consumption. Each time-per-month increase in cured meat consumption was associated with a 3.85 ml decrease in FEV1 and −0.07% decrease in FEV1/FVC.
The frequency of cured meat consumption was positively associated with odds of COPD (). The OR for COPD among individuals who consumed cured meat 14 times or more per month was 1.93 (95% confidence interval [CI], 1.41–2.64; p for trend = 0.001) compared with those who did not consume cured meats, after adjustment for age, sex, race/ethnicity, height, and smoking variables. Further adjustment for other confounding variables yielded similar results. Each time-per-month increase in cured meat consumption was associated with a 2% increased risk for COPD (multivariate OR, 1.02; 95% CI, 1.01–1.03). shows a monotonic increase in OR for mild, moderate, severe, and severe or very severe COPD across these categories. Severe and very severe COPD categories were combined because of the small number of participants with very severe COPD (n = 34) in this study. The separate ORs were 2.51 for severe COPD and 352 for very severe COPD; both ORs were statistically significant.
Figure 1. Odds ratios of chronic obstructive pulmonary disease (COPD) comparing individuals who consumed cured meat 14 times or more per month with those who did not consume cured meats according to COPD severity. Error bars are 95% confidence intervals for the (more ...)
The sensitivity analysis using the LLN definition of COPD (FEV1
/FVC < [FEV1
) yielded similar results (15
). The multivariate-adjusted OR for COPD in this analysis was 1.67 (95% CI, 1.04–2.69; p for trend = 0.01) comparing the highest to the lowest category of cured meat consumption after adjustment for all the potential confounding factors.
Multivariate analyses stratified by smoking status showed that the inverse associations of cured meat consumption with FEV1 and FEV1/FVC persisted among 2,823 never-smokers, 2,155 past smokers, and 1,929 current smokers (), although the standard threshold of statistical significance was not met for current smokers. There was no apparent modification of the relations between cured meat consumption and lung function by smoking status (p for interaction was 0.64 for FEV1, 0.94 for FVC, and 0.66 for FEV1/FVC).
Consumption of ham and pork (e.g., cured and noncured meats, respectively) was inversely associated with lung function but these associations did not attain statistical significance. The multivariate differences between individuals consuming ham and pork five times or more per month (the highest two categories were combined because of less consumption of ham and pork) and those who never ate cured meats were −40.1 ml (p = 0.12) for FEV1, −49.7 ml (p = 0.09) for FVC, and −0.11% (p = 0.82) for FEV1/FVC. The multivariate OR for COPD comparing the two extreme categories (highest vs. lowest) of ham and pork consumption was 1.18 (95% CI, 0.80–1.73).
According to the ATS standard, we did not exclude participants with a nonreproducible test from the study. Sensitivity analyses for cured meats excluding 104 individuals with only one acceptable curve (n = 7,248) showed similar differences in lung function and in risk of COPD in the main analyses. Compared with those who did not consume cured meats, individuals who consumed cured meats 14 times or more per month had a significantly lower FEV1 (−107 ml; p for trend < 0.001) and FEV1/FVC (−2.08%; p for trend < 0.001) after adjustment for all the potential confounders. The multivariate OR for COPD comparing the highest to the lowest category of cured meat consumption was 1.78 (95% CI, 1.28–2.46) in this sensitivity analysis.