Feasibility and Acceptability of a Healthy Nordic Diet Intervention in Depressed and Non-depressed Adults

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

In the future, we plan to conduct an 8-week diet intervention to investigate whether a healthy Nordic diet improves depression symptoms. The present pilot study tested whether the planned meals and diets were well-liked and accepted by participants (both depressed and non-depressed) in order to ensure that the future diet intervention will be feasible and successful. We also investigated whether any changes in health occurred after 8 days of this diet intervention.

After providing their written informed consent, participants were randomized to receive either a healthy Nordic diet or a control diet for 8 days. All meals were provided and minimal food preparation was required. Participants picked up their food outside the study kitchen every 3 days. Before and after the intervention, health-related self-rated questionnaires were completed. For every meal during the intervention, participants completed a questionnaire on their perceptions of the meal. Every evening a questionnaire was completed to assess dietary adherence. At the end of the study, a final evaluation questionnaire was completed to assess participants' perceptions of the diet and study as a whole.

Inclusion Criteria:

• If depressed, a score between 13 and 34 on the Montgomery-Åsberg Depression Rating Scale, self-rated (MADRS-S), indicating mild or moderate depression

Exclusion Criteria:

• A score of 8 or higher (out of a maximum of 12 points) on a brief diet survey (the retired version of the Swedish Food Agency's online Matvanekollen, conducted via phone interview), indicating a relatively healthy habitual diet
• Presence of food allergies, intolerances or sensitivities
• Consuming any form of special diet that excludes certain foods, for example a vegetarian or gluten-free diet
• Suicidality, indicated by a score of 4 or higher on the MADRS-S suicidality question.