It turns out that comfort food might be anything but comfortable if you suffer from common mental health issues.
A growing body of research is discovering that food doesn’t just affect our waistline but also our moods, emotions, and even longer-term conditions like depression. Which makes sense, after all. Our brains are physical entities, running on the energy that we put into our bodies, affected by shifts in our hormones, blood sugar levels, and many other biological processes.
Although there are many unanswered questions, the research to date can give us some guidance when we’re hunting for an afternoon snack. What we know so far can be summed up, more or less, as this: Whole-food diets heavy on fruit, vegetables, and unprocessed protein can lift our moods and protect us from depression, while too much junk food and sugar may put our mental health at risk.
Can Your Diet Protect You From Depression?
A paper published this year in Psychosomatic Medicine offers one of the most up-to-date snapshots of diet and mental health—specifically, how diet might play a role in depression.The research team scoured academic journals for experiments that had asked people to change their diets and had measured the effects. In all, they found 16 studies with nearly 46,000 participants from the United States, Australia, and Europe, ranging from ages 21 to 85.
The experiments were quite diverse, prescribing a variety of diets to boost nutrient intake, reduce fat intake, or encourage weight loss. One group went on a vegan diet, while others restricted calories; many people loaded up on fruits and vegetables while avoiding meat and processed foods. Some people attended nutrition classes together, while others got personalized counseling or simply took home a set of guidelines. They followed the diet for anywhere from a couple of weeks to a few years.
The results? Overall, adopting a healthier diet did lead to reduced symptoms of depression—less hopelessness, trouble sleeping, and disconnection from others—compared to engaging in other self-improvement activities or going about life as usual.
“Including more non-processed foods, more whole foods—fruits, vegetables—is very beneficial in terms of your psychological well-being, particularly mood,” said Joseph Firth, the lead author of the paper and a research fellow at Western Sydney University.
Who Benefits Most From a Healthy Diet?
First off, diet programs tended to work better for women. Why? Besides differences in hormones and metabolism, Firth conjectured, women seem to be in a better position to benefit. They’re more likely to be depressed, and they might have more discipline at following diets than men, he said.The other half attended sessions on a similar schedule. But rather than getting diet advice, they simply spent time with a research assistant who was trained to be supportive of them—talking about topics they were interested in, like sports and hobbies, or playing games with them for an hour.
Despite how beneficial social interaction is, the diet group fared better than the social support group. After 12 weeks, they had reduced their depression and anxiety more—and they were about four times more likely to experience a remission from their depression. The more they improved their diet, the more their depression lifted.
What about anxiety? In that particular study, anxiety did go down—but on average, across all 16 studies, healthier diets didn’t seem to make people less anxious. That actually strengthens the case that diet can directly affect depression, said Firth. If the results were simply due to people feeling proud and accomplished with their new healthy habits, you would expect them to feel better all around, including less anxious. The fact that only their symptoms of depression shifted means that something deeper may be going on.
Can Your Diet Make You Happy?
It’s one thing to say that our diet might protect us from depression and other mental health issues. But could the foods we eat actually move the needle toward more positive emotions and happiness?Every day for two weeks, they answered questions about their feelings, mood, and happiness. At the beginning and the end of the experiment, they also filled out surveys about their anxiety and depression.
The diet group only managed to add one extra serving of fruit and vegetables to their daily diet. But that made a difference: Compared to everyone else, they had more energy, curiosity, creativity, and motivation; and they felt more engaged and purposeful in their lives overall—a greater sense of flourishing.
Surprisingly, though, the diet didn’t seem to change their mood or their feelings of depression and anxiety. That might be because the experiment was so short, the authors believe; while diet can give us a positive boost pretty quickly, it’s possible that mental health problems take longer to show up.
Twenty-five women were surveyed on their feelings of depression, anxiety, anger, calm, and contentment. Some continued eating as usual for 10 days, while the rest adopted a Mediterranean diet (this time with no red meat). After another round of surveys, the researchers found that the women on the Mediterranean diet felt more content.
“The nutrients consumed in everyday diets are important for individuals’ mood,” wrote Laura McMillan and her colleagues.
Eating for Well-Being
So, how should all this research inform our grocery list?Most researchers are only willing to say that diet does seem to influence our mental health in some way, although they’re not sure exactly how. “There’s no real evidence to suggest that one diet works better than another,” said Firth.
However, the big picture is reasonably clear: Try to get enough fruits and vegetables—and avoid junk food.
Since many of the research findings are stronger for women, Firth does have one further tip.
“If you’re female, then you will benefit from adopting a healthier diet in general and you don’t need to worry about what type of specific diet you’re adopting,” he said. “If you’re a man and you’re not overweight, probably don’t bother.”
In other words, at least as far as our mental health goes, we can stop obsessing about having a perfectly consistent diet—or whether we should go paleo or keto—and instead focus on cultivating healthy but sustainable eating habits. That’s the area where Firth wants to see more research, too, to figure out how to help people make lifestyle changes that last.
“It’s more important to actually stick to any healthy diet than it is to try and go for some aspirational perfect one that’s ultimately unfeasible or disgusting for you to stick to,” he said.