There is evidence that dietary factors may be important in the etiology of asthma and chronic obstructive pulmonary disease (COPD) in both smokers and nonsmokers. However, the existing data on the role of diet in the etiology of asthma and COPD come predominantly from cross-sectional studies. Prospective data are needed to properly address the role of diet in the development of asthma and COPD. Air pollution clearly exacerbates existing lung disease, but a role in the incidence of asthma and COPD in adults is not established. Prospective data are necessary to properly examine this association, but such data are few. Genetic factors are likely to play a role in modulating the effects of diet, smoking, and ambient air pollution on the risk of adverse respiratory outcomes in adults. Genetic factors may influence the metabolism of nutrients in food that are responsible for health effects. Both diet and genetics may combine to influence susceptibility to adverse effects of air pollution. Effects of air pollution are likely to be weak when averaged over whole populations and identification of susceptibility factors will help to clarify health consequences of air pollution. I am establishing several high-quality population resources to prospectively investigate effects of air pollution, diet, genetics and their interactions in relation to asthma and COPD in adults. The first population is a cohort of 63,000 older adults of Chinese ethnicity in Singapore. The cohort was established with NCI extramural funding to examine the relationship between diet and cancer. I have expanded the study to include the assessment of asthma and chronic bronchitis. The Singapore Chinese cohort is of particular interest because of the prospective collection of risk factor data. Another major strength of the study is the high quality dietary assessment, which was developed specifically for, and validated in, this population. The Singapore cohort also follows dietary patterns quite distinct from the Western populations included in existing adult respiratory studies. Other strengths of the study are the large proportion of nonsmokers and the availability of genetic samples. In FY2004, we published the first manuscript on nonmalignant respiratory disease in the Singapore cohort. In this manuscript we reported that intake of fiber, especially from fruit and to a lesser extent, soy, was protective against the development of persistent cough with phlegm production. This is among the first reports of diet in relation to nonmalignant lung disease in an Asian population. We are currently validating asthma self-reports and when this is completed will begin genetic analyses of asthma and chronic bronchitis. The second study is a collaboration with another extramurally funded cohort, the Atherosclerosis Risk in Communities (ARIC) study. We will examine relationships between traffic-related air pollution and several respiratory and cardiovascular endpoints. The ARIC study is a cohort of 16,000 adults assembled from 1987-1989 in four US communities. It is one of the few large studies with longitudinal measures of pulmonary function and measures of heart-rate variability. We have ascertained in a pilot study that there is sufficient variation in distance to major roadways and therefore we have begun a full-scale study of traffic related air pollution in relation to cardiac and respiratory outcomes in the ARIC study. The third population is the Sister Study. This NIEHS cohort will have 50,000 sisters of women with breast cancer. I have added nonmalignant respiratory disease questions to the questionnaire with the aim of examining gene-environment interaction in relation to respiratory disease in this cohort. The final population is the Agricultural Health Study at NIEHS. I am involved with a team that is analyzing questionnaire data from this study and planning for the next round of follow-up. As we collect better respiratory data on the next round of follow-up, I am interested in examining gene-environment interaction with respiratory outcomes in the study. I have been integrally involved in designing the respiratory section of the follow-up questionnaire and planning collection of objective outcome data.
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