Eliminating ultra-processed foods from diet could have surprising effect

 

Drastically reducing the consumption of ultra-processed foods (UPFs), which contain high levels of added sugars, saturated and trans fats, salt, and additives, while lacking fiber, vitamins, and other essential nutrients, could improve symptoms of depression and, to a lesser extent, anxiety, according to a preliminary study from the University of California, San Francisco (USA).

The research, published last week in the journal JAMA Psychiatry, involved 20 people with an average age of 44, 70% of whom were women. All participants had depression, a high body mass index, and at least one metabolic disorder, such as hypertension, diabetes, or high "bad" (LDL) cholesterol. Fourteen of them also suffered from anxiety.

 During the trial, one group maintained their usual diet for four weeks, while the other adopted a diet low in ultra-processed foods under the guidance of the researchers. The two groups then swapped diets.

The results showed that those who reduced their intake of ultra-processed foods by more than 85% experienced moderate to significant improvements across three different measures of depression. Anxiety scores also improved, though more modestly. Lead author Andrew Krystal emphasized that the study "successfully established the feasibility of conducting this research in a larger-scale trial."

 For her part, corresponding author Nyasha Chagwedera explained that cutting back on ultra-processed foods is not easy, as they are "highly palatable, cheap, and convenient." She added that these products "trigger the release of dopamine, the pleasure hormone, which drives cravings. Food companies work with scientists to find the precise balance of sugar, salt, and fat that makes you want to eat more and more."

The study also proposes a possible biological explanation for the link between ultra-processed foods and depression. According to Chagwedera, these foods can damage the gut's protective lining and foster a state of "leaky, unbalanced gut," potentially leading to chronic, low-grade inflammation. "In other words, junk processing can damage your gut in ways that affect your brain," the scientist noted.

Looking ahead, the researchers hope to begin enrollment for a phase 2 study in 2028.