What you eat affects your mood and, beyond that, is powerful enough to influence symptoms of depression for better or for worse. Globally, healthy diets have shifted to diets that favor processed foods and refined sugars, and the burden of depression has also risen worldwide, with 300 million people affected.1
Depression among adolescents is also on the rise, increasing by 30% in the last 10 years,2 but research suggests that changing eating habits, even for a short period of time, can lead to lasting improvements in symptoms among young adults, making dietary changes a key factor in relieving depression.3
Healthy Diet Reduces Symptoms of Depression
Researchers from Macquarie University, Australia, studied 76 students between the ages of 17 and 35 who followed a poor diet and had moderate to high levels of depression symptoms.4
One group of the participants was asked to improve their diets by cutting back on refined carbohydrates, sugar, processed meats and soft drinks, while eating more vegetables, fruits, dairy products, nuts seeds, healthy fats and anti-inflammatory spices such as turmeric and cinnamon.5
After only three weeks of healthier eating, those in the healthy diet group had significant improvements in mood and their depression scores even went into the normal range. Anxiety scores also reduced significantly, while the control group, which didn’t change their diet, experienced no changes in depressive symptoms or anxiety.
Among the 21% of participants who continued to eat a healthy diet for three additional months, improvements in mood were maintained.6 The study’s lead author, Heather Francis, said in a news release:7
"Modifying diet to reduce processed food intake and increase consumption of fruit, vegetables, fish and olive oil improved depression symptoms in young adults. These findings add to a growing literature showing a modest change to diet is a useful adjunct therapy to reduce symptoms of depression."
Past research, including a systematic review of studies involving youth aged 4.5 to 18 years, linked unhealthy diet with poorer mental health, while healthy diet led to better mental health.8
Likewise, the researchers noted, “Several systematic reviews and meta-analyses show a relationship between diet quality and depression. A meta-analysis showed that healthy diet regardless of pattern (e.g. Mediterranean, vegetarian, Tuscan) was linearly associated with reduced incidence of depression.”9
The featured study is particularly noteworthy because it shows improvements in mental health can be achieved just weeks after making healthier dietary choices, and those improvements continue as long as the healthy eating is maintained.
Processed Foods Linked to Depression in Teenagers
Accumulating evidence is highlighting the strong link between what you eat and how you feel, both mentally and physically. Researchers at the University of Alabama at Birmingham analyzed the excretion of sodium and potassium in the urine in 84 urban, low‐income adolescents, a group that may be at an increased risk of both unhealthy diet and depression.
Higher levels of sodium in the urine can be an indication of a diet high in sodium, such as processed foods and salty snacks. A low level of potassium, meanwhile, is indicative of a diet lacking in fruits, vegetables and other healthy potassium-rich foods, providing objective measures of dietary intake.
Higher sodium and lower potassium excretion rates, indicative of a fast food or processed food diet, were associated with more frequent symptoms of depression at follow up 1.5 years later.
“This study was the first to demonstrate relationships between objective indicators of unhealthy diet and subsequent changes in depressive symptoms in youth,” the study noted, with researchers adding, “Given the substantial brain development that occurs during adolescence, individuals in this developmental period may be particularly vulnerable to the effects of diet on the neural mechanisms underlying emotion regulation and depression.”10