Phase II Feasibility Study of the Efficacy, Tolerability, and Impact on the Gut Microbiome of a Low-Residue (Fiber) Diet in Adult Patients With Mitochondrial Disease

Gastrointestinal (GI) dysmotility is a common and debilitating clinical manifestation in patients with mitochondrial DNA (mtDNA)–related disease with no curative and few effective symptomatic therapies. A low-residue diet (LRD) has been shown to be effective at reducing bowel urgency, pain, and distension in functional GI-related conditions. We assessed tolerability and effects of an LRD on bowel habits in patients with mtDNA-related disease. This was a 12-week single-arm pilot study in patients with genetically determined primary mtDNA-related disease, meeting the ROME III constipation criteria. The co-primary outcomes were tolerability of an LRD (