Does Diet Have an Effect on COPD Prevalence and Incidence?

Adhering to a healthy diet was associated with a lower prevalence of chronic obstructive pulmonary disease (COPD), according to a meta-analysis published in ERJ Open Research.

Investigators from McMaster University in Hamilton, Ontario, Canada, conducted a meta-analysis of relevant publications in order to determine the strength of the association between dietary patterns and the prevalence and incidence of COPD. The study authors said current efforts to curb COPD prevalence and incidence focus on smoking cessation, which is a major risk factor, but COPD is still present in nonsmokers—this led researchers to focus on other risk factors, like diet.

Investigations into the relationship between diet and COPD have shown that high fatty acid content or high dietary fiber consumption may lead to reduced risk for COPD, in addition to consumption of high levels of fruits, vegetables, and antioxidants, the study authors summarized.

Ultimately, the investigators discovered 8 observational studies between January 1980 and November 2019 that were relevant for their analysis. Of those, 3 reported on unhealthy eating patterns, but all 8 evaluated healthy dietary patterns. None of the studies examined quality of life or mortality.

Each of the studies included adult patients (aged 20 to 75 years) and collected dietary information from patients via food frequency questionnaires, the study authors explained.

The study authors said that the papers that focused on patients adhering to a healthy diet pattern demonstrated a lower risk of COPD. But the study authors also said that these cross-sectional papers, taken together, had minimal heterogeneity. There was heterogeneity present in the cohort studies, though, they said. One other limitation of this finding was that one study only examined males, while another only examined females, the study authors noted.

The studies that reported on unhealthy diet patterns and development of COPD showed what the study authors described as a “nonsignificant increase in the prevalence of COPD.” They did add that there was significant heterogeneity among the studies, but there were insufficient study numbers to continue conducting subgroup analysis.

The investigators said they planned to do a meta-analysis of longitudinal studies looking at the relationship between unhealthy diet and COPD development, but there were only 2 studies they identified with available data.

Additionally, there was 1 study that examined the mean percent of predicted spirometric values for COPD patients and controls adhering to a DASH diet. In that study, the investigators said, there was no significant association between DASH diet adherence and spirometric outcomes with COPD. That paper did note that there was a significant decrease in the FEV1/FVC ratio in those adhering to a DASH diet compared to controls.

“Overall, adherence to a healthy dietary pattern was associated with a lower prevalence of COPD, whereas adhering to an unhealthy dietary pattern was associated with a higher prevalence of COPD (statistically not significant),” the study authors wrote.

While it is still unknown how a person’s diet may affect their risk of COPD, the study authors said it remains an important area for ongoing research.

“Additional research looking at other important outcomes in COPD (i.e. exacerbations, spirometry, quality of life, and mortality) and the cumulative effects of confounding exposures associated with COPD (i.e. pollution, sex, physical activity, occupational exposures and socioeconomic status) is also needed and will be useful in translating current research into future clinical practice,” the authors concluded.

Reference

Parvizian MK, Dhaliwal M, Li J, Satia I, Kurmi OP. Relationship between dietary patterns and COPD: a systematic review and meta-analysis. ERJ Open Res. 2020;6(2):00168-2019. doi:10.1183/23120541.00168-2019