To evaluate the feasibility of nutrigenomics as an intervention for mental health conditions, a phase I randomized controlled trial of 42 adults (19 to 50 years) with depressive disorders using a 2:1 ratio of group selection (28 in the intervention {I} group and 14 in the control {C} group) is proposed. Participants with a confirmed depressive disorder will be recruited from two local mental health clinics. Those randomized into the I group will do the gene testing and be provided personalized DNA-based dietary advice from a registered dietitian; those in the C group will also receive testing but be given general dietary advice by a registered dietitian. Pre- and post-intervention comparisons (3 and 6 weeks after a personalized nutrition plan is given) will be analyzed based on records of dietary intakes (i.e., 3 day food records and food frequency questionnaire) and psychiatric functioning (e.g., Quick Inventory of Depressive Symptomology, Hospital Anxiety and Depression Scale, Outcome Questionnaire - OQ-45). In addition, measures that track physical activity, sedentary behavior, and sleep quality as well as sociodemographics will be included as covariates. After the intervention study is completed, in-depth focus group interviews will be conducted. Participants will be asked questions that will elicit their perceptions of the nutrigenomics test and the personalized dietary advice provided as well as the behavioural response to disclosure of genetic information.