How could diet affect cystic fibrosis?

    Written by:
    Brady Holmer, Daryl Nault

    Fact-checked

    by:

    Nick Milazzo
    Last Updated: May 16, 2025

    Diet can significantly affect cystic fibrosis management, particularly via gluten-free diets and dietary counseling to address digestive complications. Additionally, although oral calorie supplements are commonly used to counteract nutrient loss, their effectiveness compared to dietary guidance alone is a topic of debate, and vitamin D levels may also influence lung function in affected individuals.

    If the small bowel has been affected by cystic fibrosis (or by common comorbidities such as celiac disease or Crohn's disease), a gluten-free diet, dietary counseling, and other dietary strategies may be helpful in treating associated digestive complications.[1][2]

    Oral calorie supplements are another common strategy used in cystic fibrosis to compensate for caloric and nutrient loss due to malabsorption. One review, however, has concluded that oral calorie supplements may be no more effective than dietary guidance or monitoring alone. In light of the current evidence, and considering the high costs of some oral calorie supplements, these may not be considered an essential cystic fibrosis therapy for all when less costly measures are just as effective and readily available.[3]

    Vitamin D is connected to lung function, and individuals with lower serum levels (<75 nmol/L) may see an increase in respiratory distress and dysfunction. The mechanism behind this is not yet fully understood, but further exploration of dietary/supplemental vitamin D in cystic fibrosis is warranted.[4]