Lack of Functional Benefit with Glutamine versus Placebo in Duchenne Muscular Dystrophy: A Randomized Crossover Trial

Randomized, double-blind, placebo-controlled crossover trial in 30 ambulatory boys with Duchenne muscular dystrophy recruited from three French university hospital centers. Eligibility required ability to walk at least 170 m; all 30 were randomized and completed the trial, although one was not analyzed for the primary outcome.

Oral L-glutamine at 0.5 g/kg/day was given once daily in the morning with water or yogurt for 4 months per treatment period in a randomized crossover design. Placebo was maltodextrin of equal weight, and the two 4-month periods were separated by a 1-month washout.

Glutamine did not improve walking function or muscle mass in ambulatory boys with Duchenne muscular dystrophy. Walking speed was stable and showed no benefit versus placebo, and 2-minute walk distance, work, power, serum CPK, and 3-methyl-histidine/creatinine ratio were also not improved. Body composition findings did not favor glutamine: fat-free mass increased less with glutamine than placebo, and DXA fat mass percentage was 20.2% after glutamine versus 18.5% after placebo (p = 0.03). The intervention was generally well tolerated, with only minor adverse events reported.

The trial was small and limited to ambulatory boys with Duchenne muscular dystrophy from three French centers, which restricts generalizability. The crossover design and order effect complicate interpretation of body-composition outcomes, and each treatment period was only 4 months. The study was not powered to detect modest subgroup effects, and some outcome data were incomplete for primary analysis in one participant.