A team of researchers at the University of Edinburgh has launched a pioneering clinical trial to investigate whether a ketogenic diet—a high-fat, low-carbohydrate regimen—can alleviate symptoms of bipolar depression. The study, funded with £8 million, aims to provide robust evidence on the potential of dietary intervention as a treatment option for bipolar disorder, a condition that affects up to one million people in the United Kingdom.
The trial follows the experience of Iain Campbell, a Scottish research fellow specializing in metabolic psychiatry, who noted significant improvement in his own bipolar depression after adopting a low-carb, high-fat diet nearly a decade ago. Campbell initially began the diet to lose weight but observed unexpected relief from the severe depressive episodes that had long impaired his quality of life. This personal observation prompted further research into the metabolic underpinnings of bipolar depression.
Bipolar disorder is characterized by alternating episodes of mania and depression, with many patients experiencing persistent depressive symptoms that often resist standard antidepressant treatments. Campbell and his colleagues suggest that these depressive states involve systemic metabolic dysfunctions beyond the brain, including fatigue and weight gain. They hypothesize that the ketogenic diet could modify brain metabolism by shifting energy production from glucose to ketones—a type of molecule the brain can use as an alternative fuel.
The ketogenic diet has a well-established clinical record in epilepsy treatment for more than a century, and some antiepileptic drugs are also employed in managing bipolar disorder, supporting a potential link between metabolism and mood regulation. Previous smaller studies have reported promising metabolic and neurological changes in people with bipolar disorder following a ketogenic diet, but these efforts lacked the size and rigor necessary to draw firm conclusions.
The new randomized controlled trial plans to enroll 200 participants diagnosed with bipolar disorder. Half will follow a ketogenic diet for 12 weeks, while the other half will receive standard NHS dietary guidance. Participants will maintain their usual medication throughout the study. Researchers will assess changes in mood and energy levels and conduct brain imaging on about half the volunteers to examine any neurological correlates of symptom improvement.
Professor Daniel Smith, also affiliated with the University of Edinburgh and one of the trial’s lead investigators, described the concept of using diet to treat bipolar depression as innovative and potentially transformative. However, he cautioned that there is currently no definitive proof the ketogenic diet is effective and emphasized the need for careful evaluation to determine which patients might benefit, if at all.
Campbell echoed this sentiment, acknowledging the significant suffering caused by bipolar disorder and expressing hope for the trial’s outcomes. He stressed that a large-scale, controlled study is essential to confirm whether ketogenic diets could serve as a viable adjunct treatment for a broader population living with bipolar depression.