Clinical Benefits of Exogenous Ketosis in Adults with Disease: A Systematic Review

Background/Objectives: Ketone bodies are increasingly studied for their potential therapeutic effects, particularly through exogenous ketosis, in a variety of diseases. This systematic review aimed to rigorously assess the clinical efficacy of exogenous ketosis in adults with medical conditions. Methods: Following PRISMA guidelines, we systematically searched MEDLINE and Scopus databases. Our inclusion criteria were defined according to the PICOS framework, focusing on studies involving exogenous ketosis in adult patients with specific diseases. The study is registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42023492846). Results: After a stringent selection process, fifty-one studies were analyzed. Twenty-two studies focused on neurological disorders, one on psychiatric disorders, twenty-two on metabolic disorders, five on cardiovascular disorders, and one on an inflammatory disorder. Exogenous ketosis demonstrated potential benefits across multiple conditions, including Alzheimer’s disease, mild cognitive impairment, McArdle’s disease, various forms of heart failure, cardiogenic shock, pulmonary hypertension, and COVID-19-related acute respiratory distress syndrome, although evidence is mostly limited to surrogate endpoints with insufficient hard outcome data. Subtherapeutic ketone concentrations induced by medium-chain triglycerides and limited follow-up periods often precluded firm conclusions regarding clinically meaningful outcomes. Conclusions: Exogenous ketosis shows potential in neurological, metabolic, and cardiovascular disorders, while evidence in psychiatric and inflammatory conditions remains scarce and preliminary. Ketone esters appear preferable for effective and tolerable ketosis. Future research should focus on identifying responsive patient populations, optimizing treatment regimens, and conducting long-term clinical trials with hard endpoints to validate these findings.