The hypothesis to be tested by this study is that an intervention promoting adherence to the MedDiet can decrease symptoms of depression in patients with elevated inflammation biomarkers, namely C-reactive protein (CRP) and Interleukin 6 (IL-6) diagnosed with Major Depression Disorder (MDD), under treatment with antidepressant medication for a period of time less than or equal to 6 months. The main aim of this study is to understand if promoting the adherence to the MedDiet, as an adjuvant strategy in the treatment of MDD, is effective in decreasing symptoms of depression in MDD patients, with elevated levels of inflammation biomarkers. Other specific objectives of the study are 1. To assess the association between adherence to MedDiet and changes in inflammatory biomarkers; 2. To assess the association between changes in inflammatory biomarkers with symptoms of MDD; 3. To evaluate the association between adherence to MedDiet and effectiveness of psychiatric treatment of MDD; 4. To characterize the association between adherence to MedDiet and changes in health-related quality of life 5. To evaluate the economic cost-effectiveness of dietary counselling, as an adjuvant treatment in MDD. The study will have a duration of 12 weeks, with a randomized parallel-group open controlled trial design, with two parallel groups with an allocation ratio of 1:1 - (a) intervention arm with six nutritional consultations with a registered nutritionist, promoting adherence to MedDiet, in addition to MDD Treatment-As-Usual (TAU) and (b) control group arm benefitting only from MDD TAU. A follow up assessment will be performed at 6- and 12-months. Having into consideration an attrition of 40 percentage at the end of the intervention, the minimum sample size estimated is 190 (95 per arm). The main outcome of the trial, changes in symptoms of depression, will be evaluated using the Beck Depression Inventory Second Edition (BDI-II).