Greater adherence to the Dietary Approaches to Stop Hypertension (DASH) diet was associated with a significantly reduced risk of chronic obstructive pulmonary disease (COPD) and improved lung function, based on data from more than 28,000 individuals in the United States.
but the effects of specific diet models such as the DASH diet and Mediterranean diet on COPD in particular has not been well studied, Jingli Wen, MD, of Nanjing Medical University, Jiangsu, China, and colleagues wrote.
In a study published in Frontiers in Nutrition, the researchers reviewed data from 28,605 adult participants in the National Health and Nutrition Examination Survey from 1999 to 2018.
The study population included 2,488 individuals with COPD participants and 25,607 individuals without COPD; the mean ages of the COPD and non-COPD groups were 60.2 years and 56.9 years, and the proportion of women was 63.7% and 51.4%, respectively. The primary outcome was the prevalence of COPD, defined as self-reports of a diagnosis of chronic bronchitis or emphysema. DASH diet scores were based on consumption of nine target nutrients: saturated fat, total fat, protein, cholesterol, fiber, magnesium, calcium, potassium, and sodium. Scores for compliance with the Mediterranean diet were based on intake of eight food categories: fruits, vegetables, legumes, fish, red meat, dairy products, alcohol, and olive oil.
Overall, a higher score for adherence to the DASH diet was significantly associated with a lower COPD risk (odds ratio, 0.83; P = .021). This association remained significant in subgroups of younger adults (OR, 0.74), men (OR, 0.73), and smokers (OR, 0.82).
By contrast, adherence to the Mediterranean diet was not significantly associated with COPD prevalence (OR, 1.03; P = .697).
The researchers also found a correlation between DASH diet adherence and improved lung function, especially among individuals without COPD. The risk of FEV1: forced vital capacity decrease, as well as dyspnea, cough, and expectoration, were negatively associated with greater adherence to the DASH diet, but greater adherence to the Mediterranean diet was only negatively associated with cough risk.
The relationship between the DASH diet and reduced COPD risk persisted after adjusting for occupational exposure and excluding participants with cardiovascular disease, cancer, or diabetes.
The current study is the first known to focus on the association between DASH diet and the risk of COPD among adults in the United States, the researchers wrote. The lack of effect of the Mediterranean diet on COPD, in contrast to some studies in other countries, “suggests that regional differences in diet may affect the role of diet in the development of COPD.”
The study findings were limited by several factors including the cross-sectional design that prevented conclusions of causality, the researchers noted. Other limitations included the lack of data of the impact of poor living habits, such as smoking, on food decisions, the use of short-term 24-hour dietary recall, and the reliance of self-reports for a diagnosis of COPD.
However, the results support the role of diet in COPD pathogenesis and expand the knowledge of relationships between the DASH diet and major chronic diseases, the researchers said. More prospective studies and clinical intervention studies are needed, but the findings should encourage clinicians to consider the potential role of a healthy diet in promoting lung health.
The study was supported by the Department of Health, Jiangsu Province, China. The researchers had no financial conflicts to disclose.