Efficacy of the ketogenic diet on mental health and glycemic metrics in oncological care: A systematic review with meta-analysis
by Yao Chen, Yongting Pan, Qian Zhao, Minxiao Gu
Psycho-Oncologie
, Vol.20, No.1, 2026;
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Background: Cancer and its conventional treatments pose not only a physiological burden but also cause significant psychological distress, including anxiety, depression, and diminished quality of life. The ketogenic diet (KD), a high-fat, very-low-carbohydrate nutritional regimen, has garnered interest in oncology due to its potential to influence tumor metabolism by inducing ketosis and lowering blood glucose. Methods: A comprehensive literature search was conducted across multiple electronic databases (PubMed, MEDLINE, Embase, Cochrane CENTRAL, Web of Science, EBSCO, PsycINFO) from inception until 1 September 2025, following PRISMA guidelines. Randomized controlled trials and non-randomized interventional studies involving adult cancer patients (any type or stage) were included. The intervention was any KD protocol designed to induce nutritional ketosis. Primary outcomes were psychological metrics measured by validated scales and fasting blood glucose. Study selection, data extraction, and risk-of-bias assessment were performed independently by two reviewers. Data were pooled using a random-effects model. Results: Eight studies involving 376 patients with various cancers (e.g., ovarian, endometrial, breast, glioblastoma) were included. The meta-analysis revealed a significant reduction in anxiety scores (HADS-A) favouring the KD group (Mean Difference [MD] = −11.13, 95% CI: −13.88 to −8.38, p < 0.00001). For depression, results were mixed; a significant effect was found on the HADS-D (MD = −11.17, 95% CI: −21.18 to −1.15, p = 0.03) but with high heterogeneity ( I 2 = 84%), while no significant effect was observed on the PHQ-9 (MD = −10.32, 95% CI: −25.45 to 4.81, p = 0.18). Quality of life showed a non-significant trend towards improvement (MD = −13.52, 95% CI: −32.70 to 5.67, p = 0.17). Metabolically, the KD consistently and significantly reduced fasting blood glucose (MD = −8.73 mg/dL, 95% CI: −12.57 to −4.89, p < 0.00001, I 2 = 0%). Conclusion: The ketogenic diet demonstrates a consistent and significant effect on improving metabolic parameters by lowering blood glucose in cancer patients. Its impact on psychological well-being is more specific, showing a robust and significant benefit for alleviating anxiety, inconsistent effects on depression, and a promising, though non-significant, trend for improved quality of life. Registration number: CRD420251160658.