Healthier diets linked with lower risk of COPD in both smokers and nonsmokers

1. Individuals with the healthiest overall diets according to the Alternate Health Eating Index 2010 (AHEI-2010) had the lowest risk of newly diagnosed chronic obstructive pulmonary disease (COPD).

1. Specifically, greater consumption of whole grains, polyunsaturated fatty acids, nuts, and lower intake of red/processed meats and sugar sweetened drinks were linked to lower risk of COPD.

Evidence Rating Level: 2 (Good)

Study Rundown: After cardiovascular diseases and cancer, COPD is the third most common cause of death worldwide. While many interventions target smoking cessation as a means of reducing the morbidity of COPD, little data exist on the effect of other modifiable risk factors, such as diet. The purpose of this study was to determine the association between diet, using information from the AHEI-2010, and the risk of being diagnosed with COPD in two large U.S. cohorts. People in the highest quintile of diet quality were more physically active, less often obese, and less likely to be current smokers compared to those with the worst diets. The incidence rate of newly diagnosed COPD was 64/100,000 person years in one cohort and 32/100,000 in the other cohort. Furthermore, this risk was inversely associated with the AHEA-2010 diet score, such that the risk of being diagnosed with COPD was one-third lower in people who had the healthiest diets. This inverse association persisted in both ex-smokers and in current smokers. By examining the effect of the individual components of the AHEI-2010 on COPD risk, the authors found individuals consuming the highest amount of whole grains and fruits to have a 30% and 19% decreased risk of developing COPD compared to those with lower intake of these foods. Finally, men with the lowest intake of red and processed meats had a 53% lower risk of COPD diagnosis.

This study benefited from the use of AHEI-2010, a diet quality scoring system that has been validated in other studies and shown to be associated with lower risk of all cause, cardiovascular, and cancer mortality. Additionally, the authors controlled for smoking status, the leading cause of COPD, and found that their results persisted. However, COPD diagnosis reporting could have introduced some error as it relied on self-reported physicians’ diagnoses, and lung function measures were not widely available. Overall, this study suggests that better diet quality, with higher consumption of whole grains, polyunsaturated fatty acids, nuts, and low intake of red and processed meats, is associated with lower risk of COPD diagnoses.

Click to read the study in the BMJ

Relevant Reading: Dietary patterns and health outcomes

In-Depth [retrospective cohort]: This study evaluated the association between diet quality, using the Alternate Health Eating Index 2010 (AHEI-2010), and the risk of newly diagnosed COPD in two large U.S. cohorts, the Nurses’ Health Study and the Health Professionals Follow-up Study which began recording details about diet every two years from 1984 and 1986 respectively. Cox hazards models, controlling for confounders such as smoking, second-hand smoke exposure, and ethnicity, were used to determine the association. An inverse graded risk of COPD was found, with a hazard ratio of 0.81 (CI_95% 0.51 to 1.29) in the fourth quintile of healthy diets to 0.67 (CI_95% 0.53 to 0.85) for the people with the healthiest diets, compared to those in the lowest quintile. This applied to both sexes, with multivariable hazard ratios of 0.69 (CI_95% 0.53 to 0.90) in women and 0.60 (CI_95% 0.34 to 1.03) in men. Furthermore, these results persisted in both ex-smokers (p for trend=0.002) and in current smokers (p for trend=0.03). The authors also looked at individual components of the AHEI-2010 score, and found highest intake of whole grains and fruit to have a 30% and 19% decreased risk of COPD diagnosis, respectively, in both sexes. Women with the lowest sugar sweetened drinks and fruit juice intake had a 21% decreased risk of COPD diagnosis (p for trend=0.02), and men with decreased red and processed meat intake had a 53% lower risk of COPD diagnosis (p for trend=0.03). Finally, the authors found no association between AHEI-2010 score and risk of adult onset asthma, a condition with great overlap with COPD.

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