Ketogenic diets potentially beneficial in depression

Ketogenic diets appear to have modest beneficial effects on depressive symptoms, as shown in a systematic review and meta-analysis.

Researchers searched multiple online databases for studies involving adults undergoing a ketogenic diet (<26 percent energy from carbohydrates or <50 g/day) intervention and assessments with validated psychiatric scales. The main study outcome was changes in psychiatric symptom severity measured by standardized scales.

A total of 50 studies involving 41,718 participants (53.4 percent female) were included in the meta-analysis. Depressive symptoms were the most frequently evaluated domain (n=41), followed by anxiety symptoms (n=29). Twenty-two studies included participants with formal psychiatric diagnoses, including bipolar disorder and major depressive disorder, while 33 studies focused on nonpsychiatric populations with metabolic, neurological, or general health conditions.

Pooled data from 10 randomized controlled trials showed that ketogenic diet had a protective association with depressive symptoms compared with control diets (standardized mean difference [SMD], −0.48, 95 percent confidence interval [CI], −0.87 to −0.10; I2=67.2 percent), with stronger associations in studies using ketone monitoring, nonobese participants, very low-carbohydrate interventions, and non–high-carbohydrate comparators.

Meanwhile, ketogenic diet had a null association with anxiety based on data from nine trials (SMD, −0.03, 95 percent CI, −0.18 to 0.12; I2=41 percent).

Across quasi-experimental studies, nine showed consistent association between ketogenic diet and decreased depressive symptoms (standardized mean change using change scores [SMCC], −0.66, 95 percent CI, −0.83 to −0.50; I2=0 percent).