Eating highly processed foods harms physical and mental health
We’ve known for decades that eating highly processed foods is linked to unwelcome health outcomes, like an increased risk of diabetes, obesity and even cancer.
More recent studies point to another major downside to these often delicious, always convenient foods: They also have a significant impact on our minds, according to an article in the New York Times.
Ultra-processed foods include packaged products like some breakfast cereals, snack bars, frozen meals and virtually all packaged sweets.
Research from the past ten or so years has shown that the more ultraprocessed foods a person eats, the higher the chances that they feel depressed and anxious. A few studies have suggested a link between eating UPFs and increased risk of cognitive decline.
What’s so insidious about these foods, and how can you avoid the mental fallout? Scientists are still working on answers, but here’s what we know so far.
What qualifies as an ultraprocessed food?
In 2009, Brazilian researchers put food on a four-part scale, from unprocessed and minimally processed (like fruits, vegetables, rice and flour) to processed (oils, butter, sugar, dairy products, some canned foods, and smoked meats and fish) and ultraprocessed.
“Ultraprocessed foods include ingredients that are rarely used in homemade recipes — such as high-fructose corn syrup, hydrogenated oils, protein isolates and chemical additives” like colors, artificial flavors, sweeteners, emulsifiers and preservatives, said Eurídice Martínez Steele, a researcher in food processing at University of Sao Paulo, Brazil. This classification system is now used widely by nutrition researchers.
What effect do ultraprocessed foods have on mental health?
Recent research has demonstrated a link between highly processed foods and low mood. In one 2022 study of over 10,000 adults in the United States, the more UPFs participants ate, the more likely they were to report mild depression or feelings of anxiety. “There was a significant increase in mentally unhealthy days for those eating 60 percent or more of their calories from UPFs,” Dr. Hecht, the study’s author, said. “This is not proof of causation, but we can say that there seems to be an association.”
New research has also found a connection between high UPF consumption and cognitive decline. A 2022 study that followed nearly 11,000 Brazilian adults over a decade found a correlation between eating ultraprocessed foods and worse cognitive function (the ability to learn, remember, reason and solve problems). “While we have a natural decline in these abilities with age, we saw that this decline accelerated by 28 percent in people who consume more than 20 percent of their calories from UPFs,” said Natalia Gomes Goncalves, a professor at the University of São Paulo Medical School and the lead author of the study.
It’s possible that eating a healthy diet may offset the detrimental effects of eating ultraprocessed foods. The Brazilian researchers found that following a healthy eating regimen, like the MIND diet — which is rich in whole grains, green leafy vegetables, legumes, nuts, berries, fish, chicken and olive oil — greatly reduced the dementia risk associated with consuming ultraprocessed foods. Those who followed the MIND diet but still ate UPFs “had no association between UPF consumption and cognitive decline,” Dr. Goncalves said, adding that researchers still don’t know what a safe quantity of UPFs is.