Deppression is a common mental disorder, affecting more than 300 million people worldwide. The symptoms can vary in intensity, but it is different from usual mood fluctuations and short-lived emotional responses to challenges in everyday life. Although treatments for depression exist and they are usually safe and effective, less than half of people suffering from depression (and in many countries, less than 10%) seek any help with the condition.

However, it’s not just medical treatment that can have an impact on depression. There is strong epidemiological evidence that poor diet (rich in red meat and processed foods) is associated with depression. The reverse has also been shown: eating a healthy diet rich in fruit, vegetables, fish, and lean meat, is associated with reduced risk of depression. There has only been one randomized controlled trial to test this hypothesis, however — until now.

Food vs depression

The new study assessed the potential of a healthy diet to reduce depression symptoms in young adults — one of the most at-risk groups when it comes to depression. Heather Francis from Macquarie University, Australia, and colleagues studied 76 university students (17-35 years old) exhibiting moderate-to-high depression symptoms. All the students had poor diets — rich in sugars, saturated fats, and processed foods.

The participants were randomly placed in one of two groups: a ‘business as usual’ group, and a ‘diet change’ group. The diet change group was given brief instructions on how to improve their diet, as well as a $60 voucher to spend on groceries. They also received two subsequent check-in phone calls. Meanwhile, the control group received nothing whatsoever and was told to return in three weeks.

The researchers assessed the participants for depression, anxiety, and overall mood, both before and after the intervention. They found that only 21% of the group stuck to the healthy diet changes, but all of those who did reported significant improvements in depression symptoms and overall mood.

There are several significant limitations to this study which should be mentioned. For starters, it’s a small sample size, and university students might not be representative of the entire young adult segment. Second, as most studies of this type, it relies on self-reported information — which may not be accurate (people are notoriously bad at recalling their diets). Lastly, in an ideal scenario, the control group would have also received an intervention, just one that didn’t really change their diet. This would help eliminate the possibility that it’s a change in the diet itself that’s accountable for the improvement — but the changes towards a healthier diet. In other words, there is a chance the mere fact that people were working on changing something might account for some of the improvement.

Nevertheless, the results seem to support previous findings, that a healthy diet can be a simple intervention to tackle depression. The researchers add:

“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.”

However, this should not be interpreted as ‘all you need to get rid of depression is good food’ — depression is a serious mental condition and while a healthy diet can help, it is definitely not a panacea.

So what was the healthy food?

If you or someone else is struggling with depression, switching to healthier diets is one of the best things you can do. Here’s a rundown of what the healthy intervention in this study consisted of.

The biggest shift is eating more servings of fruits and vegetables; on average, participants ate six more servings of fruit and vegetable per week, which is essentially just one serving per day. Researchers note that participants “who had a greater increase in fruit and vegetable intake showed the greatest improvement in depression symptoms” .

Eating more whole grains (and replacing white grains) was also an important shift. Protein from lean meats, poultry, eggs, tofu, and beans was also encouraged. In addition, they were also told to eat three servings of fish per week.

Regarding dairy, the recommendation was three small servings per day — but only unsweetened dairy. Participants were also instructed to consume three tablespoons of nuts and seeds per day and were advised to add spices in their food (such as turmeric and cinnamon).

This is pretty much the cookie-cutter Mediterranean diet: low in fats and meats, high in fruits, vegetables, whole grains, and nuts. This makes a lot of sense, particularly since a meta-analysis of 22 previously published studies showed that the Mediterranean diet was associated with a lower risk of depression — but also because the Mediterranean diet seems to be associated with an improvement in overall health.

This can be adapted with relative ease (for instance, to a vegetarian diet) and is not really strict. You can tweak it to your heart’s content, while sticking to the core principles.

The study was published in the journal PLoS.