Feasibility and Acceptability of a Healthy Nordic Diet Intervention for the Treatment of Depression: A Randomized Controlled Pilot Trial

Abstract

Healthy diet interventions have been shown to improve depressive symptoms, but there is a need for randomized controlled trials (RCTs) that are double blind and investigate biological mechanisms. The primary objectives of this randomized controlled pilot trial were to test the palatability of the meals and the acceptability of the intervention in preparation for an 8-week RCT in the future, which will investigate whether a healthy Nordic diet improves depressive symptoms in individuals with major depressive disorder, and associated biological mechanisms. Depressed (n = 10) and non-depressed (n = 6) women and men were randomized to receive either a healthy Nordic diet (ND) or a control diet (CD) for 8 days. Participants were blinded to their diet allocation and the study hypotheses. Health questionnaires were completed before and after the intervention and, throughout the study, questionnaires assessed participants’ liking for the meals, their sensory properties, adherence, and open-ended feedback. In the ND group, 75% of participants consumed only the provided foods, as instructed, compared to 50% of CD participants. The meals of both diets, on average, received good ratings for liking and sensory properties, though the ND ratings were somewhat higher. Overall, results were positive and informative, indicating that the planned RCT will be feasible and well-accepted, with some proposed modifications.

Nordic diet and its benefits in neurological function: a systematic review of observational and intervention studies

“…A 8-day randomized controlled pilot trial conducted in Sweden involving 16 women and men aged between 18 and 65 years with major depressive disorder in a controlled setting with provided foods, demonstrated that a healthy ND compared to a control diet was related to a greater reduction in depressive symptoms ( 55 ). Studies with a stronger methodology, that consider a longer period and larger sample size, may help to confirm the findings of this study.…”

A Possible Antidepressive Effect of Dietary Interventions: Emergent Findings and Research Challenges

“…This diet may have mood-stabilizing properties through altered excitatory/inhibitory status affecting the signaling of the neurotransmitters dopamine, GABA, and glutamate, as well as more effective ATP production with a reduction of reactive oxygen species production [ 66 , 67 ]. Another study currently undergoing recruitment is a pilot RCT with 8 weeks of a healthy Nordic diet versus a control diet for individuals with MDD [ 68 ]. The Nordic diet consists of a high intake of vegetables and is associated with reduced inflammation and improved metabolic markers, insulin sensitivity, and cognition [ 68 ].…”

“…Another study currently undergoing recruitment is a pilot RCT with 8 weeks of a healthy Nordic diet versus a control diet for individuals with MDD [ 68 ]. The Nordic diet consists of a high intake of vegetables and is associated with reduced inflammation and improved metabolic markers, insulin sensitivity, and cognition [ 68 ]. In addition, a multi-site RCT implemented the vegan diet for 18 weeks in which significant improvements in depressive symptoms were shown [ 69 ].…”