Emma Miller
There’s a lot you can do to lift your mood and improve your mental health. As people around the world struggled with increased levels of stress, depression, and anxiety last year, many turned to their favorite comfort foods: ice cream, pastries, pizza, and hamburgers.
But recent research shows that the high-sugar, high-fat foods we often crave when we’re stressed or depressed, no matter how comforting they may seem, are the least likely to benefit our mental health.
Instead, whole foods such as vegetables, fruits, fish, eggs, nuts and seeds, beans and legumes, and fermented foods such as yogurt are better suited. The findings come from a newly emerging field of research known as nutritional psychiatry, which studies the relationship between diet and mental health.
The idea is that eating certain foods can boost brain health. But historically, nutrition research has focused mainly on how the foods we eat affect our physical health, not our mental health. For a long time, the potential impact of food on happiness and mental well-being was, as one group of researchers recently put it, “virtually ignored.”
But over the years, more and more research has provided intriguing clues about how foods can affect our mood. A healthy diet promotes a healthy gut, which communicates with the brain through the gut-brain axis.
Microbes in the gut produce neurotransmitters such as serotonin and dopamine, which regulate our mood and emotions, and the gut microbiome affects mental health.
“A growing body of literature shows that the gut microbiome plays a crucial role in a variety of mental disorders, including major depressive disorder,” a team of scientists wrote in the Harvard Review of Psychiatry last year.
Large population-based studies have also shown that people who eat a lot of nutrient-rich foods suffer less from depression and have higher levels of happiness and mental well-being.
One such study, conducted in 2016, which followed 12,400 people for approximately seven years, found that those who increased their fruit and vegetable consumption during the study period rated themselves significantly higher on questionnaires about their overall level of happiness and life satisfaction.
However, extensive observational studies can only show correlations, not causation, which raises the question: What comes first? Are people driven to choose unhealthy foods because of anxiety and depression, or vice versa? Are happy and optimistic people more motivated to consume nutritious food? Or does a healthy diet directly improve their mood?
The first major study to shed light on the link between food and mood was published in 2017. A team of researchers wanted to find out if dietary changes would help alleviate depression, so they recruited 67 people with clinical depression and divided them into groups.
One group went to meetings with a nutritionist who taught them how to follow a traditional Mediterranean diet. The other group, acting as a control, met regularly with a researcher who provided social support but did not give any nutritional advice.
At the beginning of the study, both groups consumed many sugary foods, processed meats, and salty snacks and very little fiber, lean proteins, or fruits and vegetables. But the diet group made big changes. They replaced candy, fast food, and pastries with whole foods such as nuts, beans, fruits, and legumes. They switched from white bread to whole wheat and sourdough bread. They gave up sweet grains and ate muesli and oatmeal. Instead of pizza, they ate vegetable roast. And they replaced highly processed meats like ham, sausages, and bacon with seafood and small amounts of lean red meat.
It is important to note that both groups were advised to continue taking any antidepressants or other medications they were prescribed. The goal of the study was not to see if a healthier diet could replace medication, but whether it could bring additional benefits, such as exercise, good sleep, and a different lifestyle.
After 12 weeks, the average depression scores improved in both groups, which is to be expected from anyone who has participated in a clinical trial that provided extra support, no matter which group you were in. But depression scores improved to a much greater extent in the group that followed the healthy eating plan: about a third of these people were no longer classified as depressed, compared to 8 percent of people in the control group.
The results were impressive for a number of reasons. The diet improved mental health, even though participants did not lose weight. People also saved money by eating more nutritious foods, demonstrating that a healthy diet can be economical. Before the study, participants spent an average of $138 per week on food. Those who switched to low-fat, healthy foods increased their food spending to $112 per week.
The recommended foods were relatively inexpensive and available in most grocery stores. They included foods such as canned beans and lentils, canned salmon, tuna, and sardines, as well as frozen and regular foods, said Felice Giacca, lead author of the study.
“Mental health is a complex process,” said Dr. Giacca, director of the Center for Nutrition and Mood at Deakin University in Australia and president of the International Society for Research in Nutritional Psychiatry. “A salad won’t cure depression. But there is a lot you can do to boost your mood and improve your mental health, and it can be as simple as increasing your intake of plants and healthy foods.”
A number of randomized trials have reported similar results. In one study of 150 adults with depression published last year, researchers found that people instructed to follow a Mediterranean diet with added fish oil for three months had greater reductions in symptoms of depression, stress, and anxiety after three months compared to the control group.
However, not all studies have yielded positive results. For example, a large, year-long study published in JAMA in 2019 found that the Mediterranean diet reduced anxiety but did not prevent depression in a group of high-risk people. Taking supplements, such as vitamin D, selenium, and omega-3 fatty acids, had no effect on either depression or anxiety.
Most psychiatric professional groups have not adopted dietary recommendations, in part because experts say more research is needed before they can prescribe a specific diet for mental health.
But public health experts in countries around the world have begun to encourage people to adopt lifestyle choices such as exercise, good sleep, a healthy diet, and quitting smoking, which can reduce inflammation and have benefits for the brain. The Royal Australian and New Zealand College of Psychiatrists have issued clinical practice guidelines that recommend that doctors address diet, exercise, and smoking before starting treatment or psychotherapy.
Individual doctors are also already incorporating nutrition into their work with patients. Dr. Drew Ramsey, a psychiatrist and associate clinical professor at Columbia University College of Physicians and Surgeons in New York City, begins his sessions with new patients by reviewing their psychiatric history and then examining their diet. He asks them what they eat, learns their favorite foods, and finds out if there are foods he considers important for gut-brain connectivity, such as plants, seafood, and fermented foods.
