When we make these everyday food choices, many of us think first of our physical health and appearance. But there’s another factor we may want to consider in picking foods: their impact on our mental health.
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 the fruits, 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.
One-third of adults in America eat fast food on a given day. Many of us see French fries and chocolate cake as treats to cheer us up when we’re feeling down. But perhaps our perspective on food needs an update. With a few simple dietary changes, you might be able to improve both your mind and your mood.
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 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,” says Joseph Firth, the lead author of the paper and a research fellow at Western Sydney University.
But the results got more interesting when the researchers started to dig into the details, to see for whom and under what conditions our diet might keep the bad feelings at bay.
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, he says, they might have more discipline at following diets than men.
Also, the diet programs worked better if a dietary professional administered them—probably because the recommendations were sounder and the participants (believing in the dietitian’s authority) were more apt to follow them, Firth says. An earlier review of diet studies came to a similar conclusion.
One of the strongest studies in the collection suggested that diet could help people who were right in the midst of a major depressive episode. Researchers recruited 67 depressed people with poor diets, half of whom were instructed to follow a healthy, Mediterranean-style diet favoring whole grains, fruit and vegetables, legumes, low-fat dairy, nuts, fish, lean red meat, chicken, eggs, and olive oil while reducing sweets, refined grains, fried and fast food, processed meats, and sugary drinks. Across 12 weeks, they attended seven sessions with a dietitian who helped them set diet goals and stay motivated; they also received recipes, meal plans, and a hamper of food.
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.