Glutamine supplementation in cystic fibrosis: A randomized placebo-controlled trial

Pulmonary infection and malnutrition in cystic fibrosis are associated with decreased survival. Glutamine has a possible anti-microbial effect, with a specific impact against Pseudomonas aeruginosa. We aimed to test the hypothesis that oral glutamine supplementation (21 g/day) for 8 weeks in adults with cystic fibrosis would decrease pulmonary inflammation and improve clinical status.

The study design was a randomized double-blind placebo-controlled study design with an iso-nitrogenous placebo. The primary analysis was intention to treat, and the primary outcome was change in induced sputum neutrophils.

Thirty-nine individuals were recruited and thirty-six completed the study. Glutamine supplementation had no impact on any of the outcome measures in the intention-to-treat analysis. In the per protocol analysis, glutamine supplementation was associated with an increase in induced sputum neutrophils (P = 0.046), total cells (P = 0.03), and in Pseudomonas isolation agar colony forming units (P = 0.04) compared to placebo.

There was no effect of glutamine supplementation on markers of pulmonary inflammation in the intention-to-treat analysis.