Could cutting out ultra-processed foods help fight depression?

A small UCSF study found a striking drop in depression symptoms among people who radically changed their diets to cut out almost all ultra-processed foods.

The results don’t suggest a panacea for depression: No one is going to tell depressed people to stop eating chips if they want to feel better. But they highlight the strong link between diet and mood and suggest that what people eat could be a target for treating depression, which is a widespread and in some cases intractable problem.

“This opens the door to a new area of ​​research for depression research,” said Dr. Andrew Krystal, a psychiatrist at UCSF and lead author of the study. “We attack things with expensive, high-tech solutions, like drugs, which is a good thing. But food has been neglected.”

Depression affects nearly one in five adults in the United States, according to the Centers for Disease Control and Prevention. Although there are treatments that can help many people manage this disorder, some cases are more difficult. And this disease is so prevalent that many people don’t receive care simply because there aren’t enough providers to see them.

That’s why it’s so important to find new treatments for depression and other mood disorders, mental health experts say.

Scientists have long been aware of the connection between diet, the gut, and moods like depression. Studies have found correlations between the Mediterranean diet, for example, and lower rates of depression and anxiety.

Indeed, the vagus nerve, a major neuronal connector between the brain and the body, has numerous connections with the intestine. “In reality, what happens in the gut has direct effects on neural pathways,” said Dalia Perelman, a research dietitian at Stanford.

And most people are aware, to some extent, of how their diet can affect the way they feel: Who hasn’t been “hungry” before? Or have you experienced shock after a heavy meal? Delicious foods can even have a comforting effect.

However, understanding the role diet plays in mental health is difficult because food interacts with all parts of the body. And the effect goes both ways: what people eat affects how they feel, and how they feel affects what they eat.

Ultra-processed foods could harm mental health through various mechanisms: perhaps their high fat and sugar content causes the release of certain hormones that can affect mood. Or they may contain additives that impact the brain.

“The brain is very sensitive to the impact of diet,” said Maryam Makowski, a medical nutrition scientist at Stanford. “A few studies have shown that if you eat processed foods high in sugar and fat today, you will feel worse two days later. But you may also experience changes within a few days or even hours.”

Dr. Nyasha Chagwedera, first author of the UCSF study, said ultra-processed foods could cause damage to the gut, which would then have more widespread effects.

“This intestinal damage can create chronic, low-grade inflammation throughout the body, which directly causes depression or makes people more vulnerable to it,” Chagwedera said. “In other words, an unwanted treatment can harm your gut in a way that trickles down to your brain.”

Ultra-processed foods, which are typically engineered in labs to be tastier and last longer, are not inherently bad. But scientists can’t say exactly how they can affect the body and mind. The new UCSF study, published last week in the journal JAMA Psychiatry, is among the first to demonstrate that cutting out these foods can lead to a quantifiable reduction in depression symptoms.

The study included just 20 participants, many of whom were recruited from the UCSF depression clinic waitlist. All participants were depressed, most also had an anxiety disorder, and all were overweight and had at least one metabolic disorder.

Participants were trained to remove almost all ultra-processed foods from their diet. All participants spent four weeks eating their usual diet and four weeks eating a diet low in processed foods, and the scientists compared their depression symptoms during the two periods.

The main goal of the trial was simply to see if it was possible for participants to make major changes to their diet. During the trial, participants managed to reduce their consumption of ultra-processed foods by 85%, and their depression significantly decreased during the weeks they cut out these foods.

“Reducing the amount of ultra-processed foods in our diet can be difficult, because they are very tasty, cheap and convenient,” Chagwedera said. Since she demonstrated that it is possible to get people to change their diet, Chagwedera is now planning a follow-up study with more participants.

Perelman and other scientists have noted that it’s not easy for many people to make major changes to their diet, especially when it involves cutting out foods designed to be tasty and addictive — and even more so when people are already depressed and don’t feel motivated.

But they added that major changes might not be necessary and that even small changes in diet could improve people’s mental health. Diet could be a relatively cost-effective and adaptable intervention that helps people before they seek care or while they wait for additional help.

“I learned that the best way to do this is to change your diet very slowly,” Perelman said. “You build your success because you say to yourself, ‘Yeah, I added an apple a day or a yogurt a day.’ Instead of “Wow, I’m eating fast food again,” let’s focus on the positive and keep the momentum going. »

“I just don’t want people to keep thinking all or nothing about food. It’s not that ultra-processed foods are all bad and cause depression, it’s more nuanced than that,” she said. “A diet that includes an ice cream sandwich every now and then is fantastic.”