What you eat may have more of an impact on your mood than we thought
Felice Jacka, a professor of nutritional and epidemiological psychiatry at Deakin University in Australia, has spent the past decade studying the links between diet and mental health. In a recent paper, she set out to pin down -for the first time - whether or not there is a precise connection between what people with depression ate and how they felt.
The answer is a resounding yes.
In people with moderate to severe depression, Jacka discovered, eating one specific type of healthy diet appeared to help reduce their symptoms and lift their mood, suggesting that what we eat plays a key role in how we feel.
"The idea that we might be able to help people with this very, very common and disabling condition to improve their depression by helping to improve their diet I think has great clinical significance. It also has real public health significance," Jacka told Australia's ABC News.
Today, depression is the leading cause of disability on the planet. When untreated, it can kill. Most of our current modes of treatment involve medications like SSRIs (selective serotonin reuptake inhibitors) and various forms of talk therapy, both of which studies suggest can be a huge help. Less attention has been focused, however, on the role of diet in mental health.
That's where Jacka comes in.
For the past seven years, she and members of her research team have been studying the effect that various eating plans have on people with depression. As part of her research, she's published numerous survey-based studies which hinted at the possibility that people who ate unhealthily - meaning more carbohydrate-rich junk foods, salty snacks or processed meats, and fewer fruits, vegetables, and lean meats - were at a higher risk of developing depression.
But because those studies were based on questionnaires, they lacked the power to show a precise connection between unhealthy eating and depression, much less show that eating better could actually reduce depression's often surreptitious symptoms.
So, for her new study, published in the journal BMC Medicine, Jacka enrolled 67 men and women who'd been diagnosed with moderate to severe depression and had been eating an unhealthy diet, as determined by their answers to a specific nutritional questionnaire. Most were also taking antidepressants, engaged in regular talk therapy with a therapist, or a combination of the two.
Importantly, none of the people in the study stopped their medication or psychotherapy treatment. The study was only designed to show that diet might play a complementary role in helping reduce depression. It was not designed to show or suggest that diet could be used to treat any mental illness.
Jacka then split her study participants into two groups.
For 12 weeks, members of the first group stuck to their present low-fiber, heavily-processed diet but were required to attend social support sessions. Members of the second group, on the other hand, were put on a Mediterranean diet and attended nutritional sessions with a dietitian.
As part of the new eating plan, they ate lots of fresh vegetables and some fruit, beans, unsweetened yogurt and milk products, nuts, lean meats like chicken and fish, and olive oil. They were also limited to 2 or fewer alcoholic drinks like red wine each day.
Before and after the 12-week study, Jacka graded participants' depression symptoms using a standard mood scoring test designed for people with depression.
When the study was over, the scores of the people in both groups improved, but the scores of those eating the Mediterranean diet improved significantly more. While about 8% of the people in the unhealthy diet group saw their scores improve so much that they no longer met the standard depression criteria, a whopping 32% of those in the Mediterranean group saw their scores improve that much.
Plus, more people in the Mediterranean-diet group made it all the way to the end of the study, while more people assigned to the unhealthy diet group dropped out.
These findings carry the most significance for people who struggle with depression, but they also have important takeaways for those who don't. The Mediterranean diet falls in line with many recent recommendations from registered dietitians who suggest eating more fatty foods like fish, avocados, and nuts and fewer processed foods like white rice, white bread, and sweets can help make us feel more satiated, healthier, and even lose weight.