Individual dietary intervention in adult patients with mitochondrial disease due to the m.3243 A>G mutation.

•After 3 mo of dietary intervention, 57% of personalized goals were achieved.•Of the patients studied, 97% achieved at least one goal.•Most effective goals were body composition, handgrip strength, and gastrointestinal complaints.•Consistent effect on functioning included improved handgrip strength, vitality, and fatigue score.•Effects did not seem to last after 3 mo.