RESUMEN
CONTEXT: Migraine is a headache of variable intensity that is associated with focal and systemic symptoms. A ketogenic diet (KD), a very-low-carbohydrate diet with a proportional increase in fat, causes brain metabolic alterations, which could be beneficial for some neurologic conditions. OBJECTIVE: A systematic review was conducted to assess the efficacy and tolerability of KD in preventing migraine in adolescents and adults. DATA SOURCES: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses standard was used to review articles found in the PubMed, EMBASE, Scopus, Web of Science, LILACS, LIVIVO, Science Direct, and Cochrane Central Register of Controlled Trials databases. The Google Scholar, DOAJ, ProQuest, and OpenGrey databases were included. DATA EXTRACTION: The population, intervention, comparison, outcome, and study design strategy included assessing the quality of the evidence using Grading of Recommendations Assessment Development and Evaluation and the risk of bias after applying the JBI critical appraisal tools. DATA ANALYSIS: Most of the 10 selected studies reported that KD reduced the number and severity of migraine attacks in patients, with few reported adverse effects. The evidence on the effectiveness of the KD is low, so whether the final effect is due to the treatment remains inconclusive. CONCLUSIONS: This study represents an initial effort to systematize information on the efficacy and tolerability of KD and its variations in the prevention of migraine. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42020186253.