Do we really need a study to tell us that the more ultra-processed food someone eats, the more mentally unhealthy they tend to be?

Maybe we really do.

Since the early 1990s, processed food consumption is on the rise, and whole food consumption is on the decline. If the message is out there that processed food harms us, we aren’t getting that message. Processed food consumption is up in both in children and teenagers, as well as in adults. In a study ranging from 2001 to 2018 that analyzed self-reported dietary data from over 40,000 U.S. adults, the results showed a marked increase from the start to the end of the study in how much processed food adults ate—from 53.5% in 2001 to almost 60% in 2018. Considering that people tend to overestimate how healthy their diets are (according to a recent study of 9,700 people, 85% of who thought they were eating healthier than they really were), I suspect that the amount of ultra-processed food the average American eats today is greater—perhaps far greater—than 60%.

This is a mental health disaster, in my opinion, and you’ll soon see why. But before we get into the fallout, let’s look at exactly what ultra-processed foods, or UPFs, are.

What Are UPFs?

Most foods are processed to some extent. Foods like vegetables, fruits, legumes, nuts, and seeds have to be harvested and prepared for consumption and sale. Regular processed foods need a little more preparation—things like olive oil, applesauce, white rice, whole wheat bread, cheese, and canned tuna, are changed in some way before packing. Oil must be extracted, applesauce must be cooked and pureed, white rice must be husked and dried, bread must be prepared and baked, etc.

But ultra-processed foods go beyond these simple preparation steps. These are foods that are not just minimally prepared but processed to the extent that they contain many additives and barely resemble what they once were. Examples are soda, frozen pizza, candy, chips and other salty snacks, canned soup, doughnuts, packaged baked goods, and most types of cold breakfast cereal.

More specifically when it comes to health, ultra-processed foods tend to include a lot of problematic ingredients. For one thing, UPFs contain more sugar, oil, and salt than is good for the human body. We’ve also fiddled with these ingredients. Making sugar out of high-fructose corn syrup is linked to liver damage and diabetes as well as heart disease, obesity, and general disruption of the metabolism. And repeatedly heating vegetable oils to make fried food is linked to an increased risk of cancer.

As for salt, no matter what form you use, it may be hazardous to your health. A 2022 study of over half a million people, conducted by the European Society of Cardiology, showed that people who always add extra salt to their food at the table were at a higher risk of dying during the course of the study from any cause, and had a lower life expectancy, compared to those who rarely or never salted their food. Just imagine, then, the day-in, day-out impact of consuming the extremely high amounts of salt in ultra-processed foods!

On top of all these well-studied issues, UPFs are also full of chemicals: things like artificial colors, flavorings, and preservatives, which comes with health impacts that we are only beginning to discover. For one thing, food additives may negatively impact the important balance of bacteria in the human gut microbiome, which is so instrumental in maintaining a healthy digestive system, immune system, and central nervous system.

Mental Health Consequences of Eating UPFs

Most of us are at least peripherally aware of the chronic disease risk of eating so much processed food. But what about the mental health risks? What does it mean for the future of our physical and mental health that for most Americans, about 60% of all consumed calories come from processed foods? Many different studies have linked ultra-processed foods to an increased risk of diabetes, obesity, heart disease, many different types of cancers, high cholesterol, and more. But a new study out this summer has specifically looked at ultra-processed food consumption as it relates to mental health.

I’ve been talking and writing about the connection between diet and mental health a lot lately, so I was interested to see what this study had to say, and it is definitely in line with what I’ve seen clinically. This study measured the percentage of total calories that came from UPFs in over 10,000 adults aged 18 or older. The finding: Those with the highest percentage of UPF consumption were significantly more likely to report at least mild depression, more anxious days, and more “mentally unhealthy” days per month. They were also significantly less likely to report zero mentally unhealthy or anxious days per month.

This can happen through many channels. For one thing, mental and physical health are inextricable. When the physical body isn’t working right, the central nervous system suffers, and when the brain isn’t working right, mental health issues can quickly become a problem. This can happen, for example, with nutrient deficiencies, such as low levels of B vitamins, magnesium, iron, zinc, and vitamin D, which have been linked to mood issues, anxiety and depression. UPFs are notoriously low in nutrients, so this is likely one major contributor: The more UPFs you eat, the less likely you will get the nutrients you need for healthy brain function.

Other research has also shown how certain dietary patterns might prevent or resolve mental health issues, such as eating a Mediterranean diet, or how mental health might improve by reducing specific food ingredients, like sugar (linked to depression) or saturated fat (linked to anxiety).

What’s new about this study is that it looks at the impact of UPFs as a whole. It may not matter what kind of ultra-processed food you eat.

In general, the more processed food is, the worse it is for your mental health.

There is something to consider about this study: Are the people having mentally unhealthy days having them because they are eating junk food, or are they eating junk food because they are having mentally unhealthy days? From what I can tell, the study didn’t really tease this out, but my suspicion is that this is a feedback loop: Junk food can trigger mood disorders, which can trigger cravings for more junk food. No matter the mechanism, the problem keeps getting worse. Bottom line, we know junk food is unhealthy mentally and physically, and the more you eat, the worse it is.

The Mental Health Solution

Fortunately, there is a simple solution: Eat more whole foods. Other studies have shown that a whole-food diet with minimally processed foods, especially fruits and vegetables, can improve mental health issues like depression and anxiety. One 2022 study showed that eating more fruits and vegetables was associated with worrying less, feeling less tension, and feeling more joy.

Isn’t that what we all really want? To feel less tension and more joy? Ironically, that is often the goal when people choose ultra-processed foods, and yet, as it turns out, those foods have exactly the opposite effect. For a true infusion of vibrant health, stress relief, and joy, choose whole foods, including lots of fresh fruits and vegetables, rather than the ultra-processed junk. The pleasures of junk food are short-lived, and the risks are high.The pleasures of real, whole food, the way nature made it, is the real medicine for your mental health.

RELATED: For more from Dr. Stephenson, tune in to hear her keynote address at the Naturally Informed virtual event Mental Wellness: Mastering the Market. And to view more informational and educational sessions from this Naturally Informed virtual event, register for free on-demand access.

Food & Feelings: The Hidden Connection Between Brain Health, Gut Health, & Mental Health with Dr. Stacie Stephenson.