You’ve probably heard that improving the quality of your diet can help ease the symptoms of depression. Maybe you’ve tried improving your diet, or maybe that still feels too hard right now. If you’ve already tried medication, therapy, and social support groups for your depression, it may be time to also take a look at improving the quality of your diet to help manage the symptoms of depression, says a new randomized controlled trial from Australia. The SMILES trial, conducted by a team of researchers led by Felice Jacka PhD, is the first randomized controlled trial designed to examine the link between improving diet quality and depression.
Sure, it’s not news that the foods we eat can impact our mood, but a randomized controlled trial is actually a big deal in the research world because it has the potential to show that diet can actually cause (or not cause) improved mood. This novel 12-week long study involved 67 Australian adults with depression who also had a poor diet quality defined as low intake of dietary fiber, lean proteins, fruits, and vegetables and a high intake of sweets, processed meats, and salty snacks. Participants were randomized to either a dietary intervention, receiving personal dietary advice and nutritional counseling support from a clinical dietitian in order to support optimal adherence to the recommended modified Mediterranean diet (ModiMedDiet), or a social support group which allowed participants to talk about a neutral interest such as sports or music or play card or board games with trained personnel.
Poor diet quality was defined as low intake of dietary fiber, lean proteins, fruits, and vegetables and a high intake of sweets, processed meats, and salty snacks
The ModiMedDiet, which is based on the Australian dietary guidelines and the Dietary Guidelines for Adults in Greece, supports the consumption of whole grains, vegetables, fruit, legumes, low-fat and unsweetened dairy foods, raw and unsalted nuts, fish, lean red meats, chicken, eggs, and olive oil while reducing the intake of “extras” such as sweets, refined cereals, fried foods, fast food, processed meats, and sugary drinks. Important to note is that weight loss was not the goal, so participants were encouraged to eat as they desired within the diet and no significant differences between groups were noted with respect to BMI or physical activity. Researchers also determined that this healthful diet did not cost more than a typical diet.
The intervention diet supported the consumption of whole grains, vegetables, fruit, legumes, low-fat and unsweetened dairy foods, raw and unsalted nuts, fish, lean red meats, chicken, eggs, and olive oil while reducing the intake of “extras” such as sweets, refined cereals, fried foods, fast food, processed meats, and sugary drinks
The primary change in depressive symptoms was measured using the Montgomery- Åsberg Depression Rating Scale (MADRS) and results from the 56 participants who completed the study showed the intervention group demonstrated significantly greater improvement in MADRS scores between baseline and 12 weeks than the social support control group and reflected a 7.1 point difference on the MADRS. Importantly, the significant change remained even when adjusted for different variables that may also influence the outcome aside from the intervention. Results showed that at study completion a significant difference of 32.3% of the dietary support group and 8% of the social support group achieved remission criteria. Additionally, the dietary support group compared to the social support group had significant improvements in the consumption of whole grain cereals, fruit, dairy, olive oil, pulses, and fish and intake of extras substantially declined.
Researchers noted there may be a benefit from the act of shopping, cooking, and following meal patterns which may be unrelated to the actual food items consumed. Additionally, there was the potential for expectation bias because participants were unable to be blinded to their intervention and therefore may have expected to have improved mood. The study also had a small sample size with poor diet quality to begin with. Therefore, the study results cannot be generalized to people who already have good diet quality to begin with. Participants also had different completion rates in each group and assessments were only taken at 2 points in time. There were high completion rates in the intervention group which shows the interventions were practical and accepted by participants.
So what does this study mean for you?
- If you’re currently struggling with depression and have tried several interventions including therapy, medication, or support groups and still want to see improvements in your mood, taking a look at your diet could be helpful.
- If you or someone you know would define your diet as “poor” currently, it may be beneficial to reach out to a registered dietitian nutritionist. However, this study did not examine if people who already have a fair or good diet would benefit from making diet changes. It’s not about having the “cleanest” diet. It’s just about making small changes to feel better. In fact, restricting your diet too much is sure to make you feel even more depressed.
- This study, despite its limitations, showed a link between improving diet quality with the help of a dietitian in 7 sessions over 12 weeks and an improvement in depression symptoms. You may need more or less time depending on your own situation.
- Changing your diet does not mean going “on” a diet. There was no focus on weight loss or even activity levels in this study.
- Thinking about changing your diet when you feel depressed can seem entirely too overwhelming. Consult a registered dietitian nutritionist to help you make those changes so you don’t have to do it all by yourself.