We’ve all heard the advice for years: eating fast food, processed food – sometimes called ultraprocessed food – can lead to negative consequences for physical health, and now, new research shows that consuming processed or ultraprocessed food might lead to negative consequences for psychological and emotional health, including increased risk of depression.
Published in September 2023, the peer-reviewed journal article “Consumption of Ultraprocessed Food and Risk of Depression” seeks to answer the question we pose in the title of this article: does processed or ultraprocessed food increase risk of depression?
First, let’s clarify exactly what we mean by ultraprocessed (UPC) food. The Harvard Medical School Health Blog offer this definition:
“Ultraprocessed food has many added ingredients such as sugar, salt, fat, and artificial colors or preservatives. Ultra-processed foods are made mostly from substances extracted from foods, such as fats, starches, added sugars, and hydrogenated fats. They may also contain additives like artificial colors and flavors or stabilizers. Examples of these foods are frozen meals, soft drinks, hot dogs and cold cuts, fast food, packaged cookies, cakes, and salty snacks.”
Processed food, on the other hand, has fewer additional ingredients. Per the Harvard Blog:
“Processed foods are essentially made by adding salt, oil, sugar, or other substances. Examples include canned fish or canned vegetables, fruits in syrup, and freshly made breads. Most processed foods have two or three ingredients.”
For sake of contrast, let’s also define unprocessed or minimally processed food:
“Unprocessed foods may be minimally altered by removal of inedible parts, drying, crushing, roasting, boiling, freezing, or pasteurization, to make them suitable to store and safe to consume. Unprocessed or minimally processed foods would include carrots, apples, raw chicken, melon, and raw, unsalted nuts.”
That’s the continuum. On one end, we have food with many extra non-nutritional ingredients added, in the middle we have food with one or two non-nutritional ingredients added, and on the other end, we have food with no non-nutritional ingredients added at all. Studies show that among the general population in the U.S., ultraprocessed foods contribute to 58 percent of the overall caloric intake, and account for 90 percent of energy we consume from added sugar.
That’s why this study is important: with consumption numbers like that, we need to understand the impact UPC food consumption has on our mental health. To that end, let’s take a look at the study we introduce above and learn whether the amount of processing applied to a food affects the development of depression in otherwise healthy adults.
Processed Food and Depression Risk: About the Study
To answer their primary research question, the study team used data from collected over 14 years by the Nurses’ Health Study II, a large-scale, long-term initiative designed to investigate the risk factors associated with chronic disease among women.
Here’s how the study worked:
- Subjects included 31,172 women between the ages of 42 and 62
- Subjects had no clinical depression diagnosis at baseline.
- Researchers assessed diet every 4 years using validated food consumption metrics
- Researchers examined the association between changes in ultraprocessed food (UPF) consumption with changes in depression status – using validated depression metrics – every 4 years
To enhance their understanding of the impact of ultraprocessed food on depression, the research team classified ultraprocessed foods (UPF) by type:
- Ultraprocessed grain foods
- Sweet snacks
- Ready-to-eat meals
- Fats and sauces
- Ultraprocessed dairy products
- Savory snacks
- Processed meat
- Processed beverages
- Artificial sweeteners
To add nuance to their findings, researchers used two definitions of depression:
- A strict definition, which included clinician–diagnosed depression and regular antidepressant use
- A broad definition, which included clinical diagnosis and/or antidepressant use.
After analyzing our initial findings, we controlled for possible risk factors for depression other than eating ultraprocessed food, including:
- Age
- Total caloric intake
- Body mass index
- Physical activity
- Smoking status
- Menopausal hormone therapy
- Total energy intake
- Alcohol
- Comorbidities such diabetes, hypertension, dyslipidemia)
- Median family income
- Social network levels
- Marital status
- Sleep duration
- Pain/chronic pain.
The fact the research team used advanced statistical models to control for these factors adds weight to the findings.
Quick aside: “control for” means they ensured none of the factors listed above contributed to changes in depression among the study participants.
In other words, it’s a way of making sure the outcomes are the result of the experimental variables, rather than something else. In this study, the outcomes were any change in depressive status, and the experimental variable was consumption of ultraprocessed foods.
Let’s take a look at the results.
Processed Foods and Depression Risk: Is There a Connection?
In a word, yes.
Our first takeaway from this study is not directly related to the goal of the study. However, it’s instructive to note that participants with high UPF intake at baseline, compared to participants with low UPF Intake at baseline, reported higher:
- Body mass index (BMI)
- Rates of cigarette smoking
- Rates of diabetes
- Presence of dyslipidemia (high cholesterol and lipids)
- Rates of hypertension
- Likelihood of sedentary lifestyle (no/very little exercise activity)
Now let’s look at the results for depression. Among the 30,000 + study participants, researchers identified:
- Strict definition: 2,122 cases of depression
- Broad definition: 4,840 cases of depression
Next, the let’s look at the relationship between the amount of UPF – servings per day – and depression, using both the strict definition and the broad definition.
Ultra Processed Food Intake and Depression Risk
UPC servings per day:
- First Quintile, less than 4:
- Strict definition: No increased risk
- Broad definition: No increased risk
- Second quintile, 4 to 5.3 servings per day:
- Strict definition: 11% increased risk of depression
- Broad definition: 6% increased risk of depression
- Third quintile, 5.3 to 6.8 servings per day:
- Strict definition: 22% increased risk of depression
- Broad definition: 15% increased risk of depression
- Fourth quintile, 6.8 to 8.8 servings per day:
- Strict definition: 23% increased risk of depression
- Broad definition: 20% increased risk of depression
- Fifth quintile, more than 8.8 servings per day:
- Strict definition: 52% increased risk of depression
- Broad definition: 37% increased risk of depression
Next, the research team analyzed depression risk by type of UPC ingredients. Here’s what they found.
Ultra Processed Foods and Depression Risk by UPC Ingredient Type
- Beverages sweetened with sugar: No increased risk of depression
- Dairy-based desserts: No increased risk of depression
- Basic condiments: No increased risk of depression
- Meats: 2% increased risk of depression
- Breakfast foods: 2% increased risk of depression
- Savory snacks: 3% increased risk of depression
- Frozen foods: 4% increased risk of depression
- Sweet snacks: 6% increased of depression
- Artificial sweeteners: 26% increased risk of depression
- Artificially sweetened beverages: 37% increased risk of depression
What we learn from this data is that first – yes – consuming ultraprocessed food can increase risk of developing depression. Next, we learn that the more ultraprocessed food a person eats, the greater their risk of developing depression, a finding which holds when applying both a strict and broad definition of depression. Then we learn that controlling for variables considered the usual suspects – age, total caloric intake, body mass index, physical activity, cigarette smoking, alcohol intake, physical comorbidities, mental health comorbidities, income, social support, marital status, sleep, pain – had no impact on the association of consuming UPC and depression.
Finally, the data indicates the ingredients of the UPC consumed make a significant difference. When comparing quintile 1 (low intake) to quintile 5 (high intake), high intake of artificial sweeteners increases risk of depression by 26 percent, and high intake of artificially sweetened beverages increases risk of depression by 37 percent.
What Should We Eat for Optimal Health?
That’s the question we have after reading these results. If ultraprocessed foods can increase risk of depression, then how can we avoid them?
The answer is relatively simple. The more packaging a food product has, the more likely it is to be ultraprocessed. In addition, the more ingredients – especially non-nutritive ingredients – on a label, the more processed the food inside.
That’s big picture advice, and basic rules for grocery shopping. With regards to overall diet, we’ll now share the latest dietary guidelines released by the Centers for Disease Control (CDC) and the American Heart Association (AHA).
Consuming the following foods in the following amounts decreases risk of physical disease and increases likelihood of physical, emotional, and psychological health:
Fresh Vegetables
To achieve ideal mental and physical health, the CDC and AHA advise consuming 5 portions of fresh vegetables per day. A portion of fresh vegetables equals 1 cup of raw leafy greens, ½ cup of canned, froze, or fresh vegetables, or ½ cup of vegetable juice. If you buy frozen or canned vegetables, check the label to ensure they do not contain too many additives, preservatives, or sugar.
Whole Grains
Grain products are generally sold as either refined or whole. Whole grains contain the bran, germ, and endosperm, which are the most nutritious components of any grain. Refined grains contain neither bran nor germ, and the process of refining grains removes iron, fiber, and B-vitamins, all of which make grains healthy. including B-vitamins, iron, and fiber. The CDC and AHA recommend grain consumption include at least 51 percent whole grains. Whole grains include brown rice, whole wheat, wild rice, unprocessed oatmeal, and popcorn.
Fresh Fruit
To achieve ideal mental and physical health, the CDC and AHA advise consuming 2-3 portions of fresh fruit per day. One portion of fruit equals about 1 medium-sized fruit such as an apple, ½ cup of canned/frozen fruit, ¼ cup of dried fruit, or ¼ cup of fruit juice. Note: manufacturers often add high fructose corn syrup to fruit juice, which means many fruit juice products are considered processed beverages.
Healthy Protein
Healthy proteins are lean proteins. The healthiest proteins come from plants, such as beans and nuts, as well as lean meats and low- or no-fat dairy products. The CDC and AHA recommend consuming as 5 ½ ounces of health protein every day. That means fish, seeds, beans, and nuts. Here’s basic information on meat portions:
- About ¼ cup of beans equals 1 ounce of protein.
- 1 egg equals 1 ounce of protein.
- 1 tablespoon of peanut butter equals 1 ounce of protein.
- 1 cup of ground beef equals 8 ounces of protein.
If you choose chicken, pork, or beef, it’s important to choose lean beef, boneless/skinless chicken, and consider reducing potions of pork.
In addition, the CDC and AHA advise the following about fats/oils, processed foods, salt/sugar, and alcohol.
Fats and Oils
Fats and oils that the CDC and AHA consider healthy include plant oils like soy, olive, safflower, corn, or canola. The CDC and AHA advise these fats and oils over animal products like butter and lard, and recommend avoiding partially hydrogenated fats. For optimal health, the experts advise consuming no more than 3 tablespoons (9 teaspoons) of oil or fat per day.
Reduce Salt and White Sugar Consumption
This one is not easy, because sugar and salt make everything better. We know completely eliminating sugar and salt is a non-starter for most people. With that in mind, we suggest reducing intake as much as possible, while still enjoying the flavor of your food.
Minimize Alcohol Intake
New studies show moderate alcohol intake – previously considered safe – can lead to negative outcomes. We’d also like to point out a connection between mood an alcohol. Since alcohol central nervous system depressant, a person with depression should consider avoiding anything with a depressive effect.
Avoid Processed Foods
We’re glad they advise this, because this is the entire point of this article. Also, it’s easy to identify processed foods. They’re always sold in some sort of packaging. Here’s a good rule to keep in mind when shopping for healthy foods: as we mention above, in general, the more non-nutritive ingredients on a label, the less healthy the contents.
Putting it All Together
At Crownview Psychiatric, we can use this information immediately, in at least two ways:
- We can inform all our patients with depression or depressive disorders to reduce their intake of ultraprocessed foods.
- We can avoid offering ultraprocessed foods as snacks or any other meals we provide
Those are the basics. Another way this information helps is by increasing awareness of the habits and practices that support positive mental health. As people – meaning spouses, siblings, friends – we want to give ourselves the best chance of success in life, and the best chance of leading a happy and fulfilling life. Yes, of course – there are ups and downs in life. Our natural state is to experience a range of emotions, from happy to sad to everything in between. However, if we can eat foods that don’t put us on the back foot – physically or emotionally – then we’re ahead, and increase our chances of living the life we want to live.
That starts with food: if we eat healthy food, we have a better chance of being healthy, and therefore, increase our chances of being happy. The data from the study we discuss above tell us something else: if we avoid ultraprocessed foods, we decrease our chances of developing depression.
That’s important information we can all use, starting right now.
Gianna Melendez
Jodie Dahl, CpHT