Not only did eating a healthy diet for three weeks improve depressive symptoms in college-aged young adults, but those who continued the diet for three months kept their improved outlook on life, according to a small randomized trial on diet and depression.

"Simply cutting down processed food intake and increasing fruit, vegetable(s) and fish resulted in improvements in depression symptoms," said Heather Francis, a neuropsychologist at Australia's Macquarie University and the lead author of the study published Wednesday in the journal PLOS One.

Teens in the study who had the greatest increase in fruit and vegetable consumption showed the most improvement, Francis said, and those who did not change their diet had no change in their depression from the start of the study.

The average age of participants in the study was 19.

Study participants were asked to cut back on refined carbohydrates; sugar; fatty or processed meats; and soft drinks. Highly processed foods have been shown to increase inflammation, which is a risk factor for depression, Francis said.

During the three weeks of the study, teens were asked to eat the following foods each day: five servings of vegetables; two to three fruits; three servings of grains; three servings of protein, such as lean meat, poultry, eggs, tofu, or fish (up to three times a week); three servings of unsweetened dairy; three tablespoons of nuts and seeds; two tablespoons of olive oil; and one teaspoon of turmeric and cinnamon.

Turmeric and cinnamon were included because they have anti-inflammatory properties, Francis said, as do nutrient-dense foods such as fruit, vegetables, whole grains and fish.