People Who Cut Ultra-Processed Foods Had Lower Depression Scores, but One Detail Matters

Cutting ultra-processed foods was linked to lower depression and anxiety scores in a small clinical trial—but the more useful question for your next grocery trip may be what takes their place.

The JAMA Psychiatry pilot offers an encouraging signal, not an established treatment. Nutrition expert Laura Bosman, MSc Nutrition and Health, of the European Food Information Council, says replacing those foods can change fiber, vitamins, fats, and calories simultaneously. That makes the replacement food central to understanding the findings.

The Improvement Comes With an Important Limit

Twenty adults with depression enrolled; 19 completed the study. Each followed their usual diet and a low-ultra-processed-food diet for four weeks apiece, in randomly assigned order, according to UCSF.

Average PHQ-9 depression scores were 5.53 during the low-UPF period versus 8.68 during the usual-diet period. Anxiety scores were also lower. However, symptom changes were exploratory; the main goal was testing whether participants could manage the dietary change.

“However, they knew which diet they were following, so expectations could have influenced how they experienced or reported their symptoms,” Bosman explains to Men’s Journal. “The study also couldn’t separate reducing UPFs from other changes in what participants ate.”

What You Add May Matter

Swapping a packaged snack for nuts or fruit changes nutritional quality alongside processing. This trial couldn’t establish which change explained the mood results.

“There are several plausible ways diet could influence mood, including through nutrients that support brain function and communication between the gut and brain,” Bosman says.

She points to nutrient roles in brain-cell signaling and the interaction between gut microbes and inflammation. These are possible explanations, not mechanisms demonstrated by this trial. Whether blood-sugar changes contributed also remains unresolved.

A Practical Place to Start

For adults over 40, the findings support a conversation about overall eating patterns—not a promise of preventing depression or protecting long-term brain health.

“Wholegrain bread and some fortified cereals or plant-based drinks can fall into the UPF category while providing valuable nutrients,” Bosman notes.

Start with an achievable addition: beans in a familiar dinner, frozen vegetables alongside lunch, or whole-grain bread. Larger, longer trials must establish whether benefits persist and whether processing matters independently of nutrition.

“Improving diet may therefore support mental health alongside medication or talking therapies, but it cannot replace them,” Bosman says.

The takeaway: Add nourishing foods, and keep established depression care in place.

This story was originally published by Men’s Journal on Nov 4, 2026, where it first appeared in the Nutrition section. Add Men’s Journal as a Preferred Source by clicking here.

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