People who suffer from certain chronic lung diseases may want to consider modifying their diets, if they do not already consume fruit, cheese, and fish on a regular basis. A preliminary study of 2,167 subjects with chronic obstructive pulmonary disease found that those who reported consuming fish, grapefruit, bananas, and cheese scored better on clinical outcome measures. These results were presented this week by Dr. Corrine Hanson at the American Thoracic Society Annual Meeting in San Diego, California.

Chronic obstructive pulmonary disease, or COPD, is a category of progressive diseases of the lung and airways including emphysema and chronic bronchitis. Cigarette smoking is the leading cause of COPD and according to the U.S. Centers for Disease Control and Prevention, approximately 15 million Americans suffer from COPD. It is the third leading cause of death for both men and women nationwide.

The new study, which has yet to be published in a refereed scientific journal, shows statistically significant associations between self-reported consumption of the four specific food items and improved lung function, less emphysema (loss of air sacs), improved six-minute walk and St. George’s Respiratory Questionnaire scores, and lower levels of a panel of inflammatory markers. Association studies like this one cannot demonstrate a causal link between the foods and COPD improvement, but the results will prompt researchers to look into the associations in more detail.

Hanson suggested that the COPD patients who ate the foods may have a well-rounded, healthy diet in general. “It’s probably the overall dietary pattern that matters,” Hanson said. She added that it is plausible that the specific foods examined in the study exert antioxidant and anti-inflammatory effects that result in COPD improvement.

Previous research has supported this plausible explanation. Individuals with diets rich in fruits, vegetables, whole grains, and fish are at lower risk for developing COPD, according to Harvard Medical School professor Dr. Carlos Camargo.

“We think that diet as a whole is important,” said Camargo, who was not involved in Hanson’s study.  Camargo added that the only way to move beyond association is to conduct a clinical trial in which COPD patients are randomly assigned to different diets and then followed for a defined period of time and assessed for improvement in their conditions.

“A trial like that is hard to do,” Camargo said. “But it can be done.”