High-fiber diet is associated with better lung function

By John Murphy, MDLinx
Published January 25, 2016

Key Takeaways

Adults who eat a high-fiber diet tend to have better lung function than adults who eat the least amount of fiber, according to an article published online January 19, 2016 in the Annals of the American Thoracic Society. Researchers concluded that a diet rich in fiber-containing foods may play a role in improving lung health.

The researchers noted, however, that the association between a high-fiber diet and better lung function doesn’t establish causality, and that fiber may be a surrogate measure for a person’s overall healthy lifestyle. Also, the study didn’t account for physical activity, which is relevant to dietary choices and a potential source of confounding, the researchers acknowledged.

“It’s important to identify modifiable risk factors for prevention [of lung disease]. However, beyond smoking, very few preventative strategies have been identified,” said lead author Corrine Hanson, PhD, RD, Associate Professor of Medical Nutrition at the University of Nebraska Medical Center, in Omaha, NE. “Increasing fiber intake may be a practical and effective way for people to have an impact on their risk of lung disease.”

In this study, Dr. Hanson and colleagues analyzed spirometry measures and dietary intake information from 1,921 adults in the National Health and Nutrition Examination Surveys (NHANES). NHANES participants whose diets included more than 17.5 g of dietary fiber a day were placed in the top quartile, and those whose fiber intake was less than 10.75 g a day were included in the bottom quartile.

Among adults who ate the most fiber (top quartile), 68.3% had normal lung function compared with 50.1% who ate the least fiber (bottom quartile). Also, 14.8% in the top quartile had airway restriction, compared with 29.8% in the bottom quartile. Those with the highest fiber intake also performed significantly better on spirometry measures of forced vital capacity (FVC) and forced expiratory volume (FEV).

After adjusting for smoking, body mass index, socioeconomic status, and other factors, the researchers identified an independent association between low dietary fiber intake and reduced lung function.

The researchers acknowledged that their findings don’t establish that a high-fiber diet directly improves lung function, nor did the NHANES data allow them to analyze fiber intake and lung function over time. “As lung function reflects both maximal lung function attained in early adulthood and lung function lost with aging, it is surprising we find an association at all between dietary fiber intake and contemporaneous lung function measurements,” the authors wrote.

But, if fiber intake is a surrogate measure for an overall healthy lifestyle, then a diet rich in fiber-containing foods may play a role in improving overall health—including lung health, the researchers suggested.

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