Nutrition, Inflammation and Lung Function in Middle-aged Men
Background: Forced expiratory volume in one second (FEV1) is an independent predictor of all-cause mortality and therefore variables which accelerate or slow FEV1 decline are of great potential importance to public health. Methods: From 1991 to 1994, 2745 men aged 50 to 59 years were recruited into the Belfast cohort of the Prospective Epidemiological Study of Myocardial Infarction (PRIME). 2010 of these men were rescreened at 10 years. At both time points, the men were assessed at a clinic appointment which involved blood sampling, questionnaires, anthropometric measurements and lung function by spirometry. Each individual spirometry trace (baseline and 10 year follow-up) was reviewed for validity using ATS/ERS criteria. Plasma levels of C-Reactive Protein (CRP), antioxidant vitamins (A and E) and carotenoids were measured in the stored blood samples. All statistical analyses were performed with SPSS version 15. Results: The 2745 men in the baseline cohort had a mean age of 54.8 years (SD 2.9) and 32.9% had never smoked. They were on average overweight with a mean body mass index of 26.3kg/m2 and a mean waist-hip ratio of 0.94. 1779 men had valid baseline lung function measurements by spirometry. Mean percent predicted FEV1 was 92% and mean percent predicted FVC was 96.9%. The baseline current smokers had the greatest decline in FEV1 over 10 years of 560 ml (SD 339 ml). Waist-hip ratio, body mass index and waist circumference were inversely associated with pulmonary function. FEV1 decline was related to the change in distribution of weight as well as to weight gain. Lung function and plasma C-Reactive Protein (CRP) concentrations were inversely related in both cross-sectional and longitudinal analyses. The presence of systemic inflammation was demonstrated, even in subjects with mildly reduced pulmonary function. There was also an association between annual change in CRP and annual decline in FEV1 and forced expiratory volume in one second (FVC) in the adjusted model in this population Plasma levels of retinol, lutein, zeaxanthin, ß-cryptoxanthin, α-carotene and ß-carotene were positively correlated with lung function in the cross-sectional analysis. There were also some longitudinal associations between baseline retinol, zeaxanthin, β-cryptoxanthin and 10 year lung function. Self-reported fruit and vegetable intake was positively correlated with both lung function and plasma levels of antioxidants. Conclusion: In this population of middle-aged men from Northern Ireland, lung function and lung function decline as measured by FEV1 and FVC are related to body mass index, body weight distribution, lifestyle habits (smoking and alcohol intake), social status, subclinical inflammation and diet. This data supports the current public health advice regarding healthy eating, weight control and smoking cessation.
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