Depression is a common mental disorder which affects 1 in 3 young people in Hong Kong.1 A recent study reported that simple diet intervention for 3 weeks did improve the symptoms of moderate-to-severe depression among university students.2 The diet recommendations included increasing the intake of fruits, vegetables, lean meats, and fish, and reducing the intake of refined carbohydrates, sugars, processed meat, and soft drinks.2 Researchers found significantly lower self-reported depression symptoms in the diet intervention group versus the control group, which were maintained at the 3-month follow-up. These findings supported the potential of diet improvements as an adjunct to pharmacological and psychological treatment of depression, or to reduce the risk of depression in healthy young adults.2
Approximately 1 in 3 young people in Hong Kong suffer from depression, with a survey reporting that more than 50% of university students experience mild to severe depressive symptoms.1,3 Although there are many effective treatments available for depression, many people do not receive them due to various reasons, such as social stigma and inaccurate diagnosis.4 Poor diet quality has been associated with an increased risk of depression, and is therefore a good target for the early intervention in this age group, which also overlaps with the critical periods for establishing health patterns that carry over into adulthood.2,5
A recently published randomized controlled trial, led by Dr. Heather Francis, Lecturer in Clinical Neuropsychology, Macquarie University, Australia, found that a simple change in dietary habit significantly improved the depressive symptoms among university students with elevated depression symptoms.2 38 university students were allocated to a 3-week diet intervention (DI) group who received diet instructions based on the ‘Australian Guide to Healthy Eating’.2 This included increasing the intake of vegetables, fruits, wholegrain cereals, protein (lean meat), unsweetened dairy, fish, nuts, and seeds, plus additional recommendations related to the reduced risk of depression, such as turmeric and cinnamon.2 Concurrently, refined carbohydrates, sugars, fatty or processed meats, and soft drink consumption were to be reduced.2 In parallel, 38 university students assigned to the control group were given no instructions regarding the diet and asked to return after 3 weeks for a follow-up.2
The primary outcome was symptoms of depression post-treatment, assessed by the Centre for Epidemiological Studies Depression Scale-Revised (CESD-R).2 At 3 weeks, the average CESD-R score for the DI group was significantly lower than that of the control group (p=0.007), controlling for baseline scores.2 Within the DI group, CESDR-R score had also improved from the elevated range (score >16) to the no clinical significance range after 3 weeks.2 However, scores remained elevated in the control group.2 Regression analysis showed that change in processed food intake correlated most strongly with reducing depression symptoms compared with other diet variables.2 A telephone follow-up at 3 months revealed that improvements in depression symptoms had been maintained over this period, with most participants (57.6%) reporting that they had maintained some aspects of the diet.2
The extent of improvement appeared to be associated with diet compliance, which was assessed using questionnaires (e.g. Dietary Fat and Sugar Screener) and a spectrophotometer that detected flavonoids in the skin.2 Authors of the study mentioned that an interesting finding of the study was the good rate of compliance to the diet instructions in the DI group, as several barriers were anticipated, such as perceived cost of the diet and time demands of preparing food in addition to their depression symptoms.2
To date, this is the first study to demonstrate a short and effective intervention to alleviate the symptoms of depression, as well as the feasibility of diet change in this population, which is at particularly high risk of depression.2 Previously, the SMILES trial showed a similar effect of the diet intervention in a 12-week randomized control study in an older population (mean age 40 years).6 Future research may elaborate more on the duration of these effects and the impact of varying diet composition to strengthen the evidence for the use of diet intervention as an adjunct to reduce depression symptoms.
1. One in three young Hongkongers suffering from mental health issues. South China Morning Post. https://www.scmp.com/news/hong-kong/health-environment/article/2149403/one-three-young-hongkongers-suffers-stress-anxiety. Published June 6, 2018. Accessed October 30, 2019.
2. Francis HM et al. A brief diet intervention can reduce symptoms of depression in young adults – A randomised controlled trial. PLOS ONE. 2019;14(10):e0222768.
3. Lun KW et al. Depression and anxiety among university students in Hong Kong. Hong Kong Med J. 2018;24(5):466-472.
4. Depression. https://www.who.int/news-room/fact-sheets/detail/depression. Accessed October 30, 2019.
5. Lai JS et al. A systematic review and meta-analysis of dietary patterns and depression in community-dwelling adults. The American Journal of Clinical Nutrition. 2014;99(1):181-197.
6. Molendijk ML et al. The SMILES trial: do undisclosed recruitment practices explain the remarkably large effect? BMC Med. 2018;16(1):243.