Dietary fiber is best known for supporting digestion, blood sugar balance, and heart health — but research also suggests it may play a role in lung function and respiratory health.

A study published in the American Journal of Epidemiology (2008;167(5):570–578) analyzed data from 11,897 adults participating in the Atherosclerosis Risk in Communities (ARIC) study. Lung function was measured using two standard tests:

  • Forced Expiratory Volume in one second (FEV₁): how much air can be forcefully exhaled in one second

  • Forced Vital Capacity (FVC): total volume of air expelled during a full, forceful exhalation

What the researchers found

Participants with the highest fiber intake had:

  • FEV₁ values 60.2 mL higher than those with low fiber intake

  • FVC values 55.2 mL higher than low-fiber consumers

Higher fiber intake was also linked with a 15% lower risk of chronic obstructive pulmonary disease (COPD)—a group of conditions that includes chronic bronchitis and emphysema.

  • Chronic bronchitis involves swollen, mucus-filled airways that restrict airflow.

  • Emphysema damages the alveoli (air sacs), preventing efficient oxygen exchange and trapping stale air in the lungs.

People who consumed most of their fiber from fruit had an even greater reduction in risk — 28% lower, according to the researchers.

These findings are consistent with research suggesting diets rich in plant foods may support healthier inflammatory responses in the airways and maintain lung capacity over time.