Ketogenic Diets and Depression and Anxiety: A Systematic Review and Meta-Analysis

Area of Science:

• Neuroscience
• Nutritional Psychiatry
• Metabolic Health

Background:

• Ketogenic diets (KDs) are hypothesized to impact mental health via mitochondrial function, inflammation, and neurotransmitter pathways.
• The therapeutic efficacy of KDs in psychiatric populations is not well-established.

Purpose of the Study:

• To evaluate the association between ketogenic diets (KDs) and mental health outcomes, specifically depressive and anxiety symptoms, in adults.
• To synthesize evidence from various study designs, including randomized clinical trials (RCTs) and quasi-experimental (QSE) studies.

Main Methods:

• A systematic literature search was conducted across MEDLINE, Embase, and APA PsycINFO, supplemented by manual searches.
• Included studies involved adults (≥18 years) on KDs (<26% energy from carbohydrates or <50 g/day), assessed with validated psychiatric scales.
• Random-effects meta-analyses were performed for RCTs and QSEs, with data extracted and risk of bias assessed.

Main Results:

• Meta-analysis of 10 RCTs indicated a significant association between KDs and improved depressive symptoms (SMD, -0.48; 95% CI, -0.87 to -0.10).
• Associations were stronger with ketone monitoring, nonobese participants, very low-carbohydrate diets, and non-high-carbohydrate comparators.
• Nine RCTs showed no significant association for anxiety (SMD, -0.03; 95% CI, -0.18 to 0.12), while QSEs suggested consistent improvements for both depression (SMCC, -0.66) and anxiety (SMCC, -0.58).

Conclusions:

• Ketogenic diets are associated with modest improvements in depressive symptoms, particularly when biochemical ketosis is confirmed.
• The evidence for KD efficacy in reducing anxiety symptoms is inconclusive.
• Further well-powered trials with standardized protocols, structured support, and verified outcomes are necessary to confirm KD efficacy and durability in psychiatric populations.