What journalists need to know about reducing ultra-processed foods and depression

Last Updated : 01 October 2026

Food and nutrition studies can be difficult to report on, often arriving with uncertainty, nuance, and pressure for quick headlines. These briefings are designed for journalists, breaking down what the research actually shows and providing clear context to support accurate coverage.

A new study investigated reducing ultra-processed foods from the diets of patients with depression.¹ This sparked headlines, but it needs careful context before conclusions are drawn. Here are key points journalists should consider.

The new study in less than 250 words

The small preliminary trial looked into whether people with depression could reduce their intake of ultra-processed food (UPF) and whether their depression and anxiety symptoms changed while they did so. The study included 20 US adults with depression who reported high UPF consumption and at least one metabolic abnormality, such as high body weight, insulin insensitivity or high blood pressure. Nineteen participants completed the study.

The study compared the participant's usual diet with a diet low in UPFs. Each participant followed both diets, with the order decided at random, and knew which diet they were following. The study's main aim was to assess whether reducing UPFs was feasible and acceptable. That is, whether participants could make the dietary change and how manageable they found it. Changes in depression and anxiety were exploratory outcomes, meaning the study was not designed to establish whether the diet treats depression symptoms.

Participants reported a substantial reduction in UPF consumption. They also had lower depression and anxiety symptom scores during the low-UPF period. However, this does not show that reducing UPFs itself caused the improvement. Participants knew which diet they were following, and changing their UPF intake may also have changed other aspects of their diet.

What does the headline finding mean?

Participants in the study reported fewer symptoms of depression and anxiety while they were following the low-UPF diet than while they were following their usual diet. For example, the average score on the nine-item Patient Health Questionnaire (PHQ-9), the mean score was 5.53 during the low-UPF period compared with 8.68 during the usual-diet period. The estimated difference was 3.12 points.

In practical terms, this means that participants reported fewer depression symptoms during the low-UPF period. It doesn’t mean that their risk of depression fell by 3% or that 3% more people recovered, or that reducing UPFs will reduce depression symptoms by a particular percentage.

It’s also important to distinguish what the study found from what it can tell us about cause and effect. The participants changed their overall diet, not just the amount of processing in their food. Reducing UPFs might have changed other aspects of their diets, such as calorie, fibre, sugar or fat intake. Participants also knew which diet they were following, which means that expectations about the intervention could have influenced how they experienced or reported their symptoms.

The finding is therefore best understood as a preliminary result that needs further research, rather than evidence that people with depression should use a low-UPF diet as a treatment or that UPFs itself caused the improvement.

To keep in mind if reporting

• “A clinical trial demonstrates that reducing UPFs improves depression” goes beyond the evidence. This small study mainly tested whether people with depression could follow a diet low in UPFs and how manageable they found it. Their depression symptoms were also assessed, and the improvements observed are promising. However, larger studies specifically designed to test whether this dietary change improves depression are needed before it can be recommended as a treatment.
• Being able to follow a diet is different from showing that it treats depression. Researchers first need to find out whether people can make the dietary change (feasibility) and how manageable they find it (acceptability). This study mainly examined those questions, while also checking for changes in depression symptoms. The improvements observed provide a reason to investigate that further. Larger studies would need to establish whether the diet reliably improves depression and whether any benefits last. Recommending it as a treatment would also require weighing the benefits, possible harms and practical challenges alongside existing care.
• Participants knew which diet they were following (the study was unblinded). If someone expects a dietary change to help them feel better, that expectation can influence how they experience or report their symptoms. This doesn’t mean the improvements were imagined, but it makes it harder to separate the effects of the diet itself from the effects of expecting it to help.
• The results describe changes in symptom scores, rather than the risk of depression. The questionnaires and clinical assessments gave symptoms a numerical score, with higher scores indicating more severe symptoms. A difference of three points therefore means a lower symptom score; it doesn’t mean a 3% reduction in depression risk or that 3% more participants recovered. Because participants already had depression, the study examined symptom severity rather than their likelihood of developing the condition.
• Dietary change was self-reported. Researchers assessed dietary changes using a questionnaire, rather than independently measuring everything participants ate. Their answers suggested that they ate fewer UPFs, but people may forget foods or estimate their intake inaccurately. This creates uncertainty about exactly how much their diets changed.
• The study involved people with particular health and dietary characteristics. All the participants had depression, high reported UPF consumption and a self-reported metabolic abnormality (such as high blood pressure, insulin insensitivity, or high body weight). The findings may not apply in the same way to other groups or healthy adults.

What is the current scientific consensus on the topic?

Authority	Position on UPFs, diet and depression
World Health Organization (WHO): depression care2	The WHO states that self-care can play an important role in managing symptoms of depression and promoting overall well-being. These include: trying to keep doing activities you used to enjoy, staying connected to friends and family, exercising regularly, sticking to regular eating and sleeping habits, avoiding or cutting down on alcohol and avoiding illicit drugs, talking to someone you trust about your feelings, and seeking help from a healthcare provider. A low-UPF diet is not presented as an established depression treatment.
World Health Organization (WHO): healthy diet3	The WHO emphasises dietary adequacy, balance, moderation and diversity, including a variety of minimally processed foods. It has been developing guidance specifically on UPF consumption; general healthy-diet guidance shouldn’t be read as proof that UPF reduction treats depression.

In depth

What the study showed

Twenty adults were assigned at random to start with either a low-UPF diet or their usual diet, then crossed over to the other condition. Nineteen completed the study. The main questions were whether participants could reduce their reported UPF consumption and whether they found the change acceptable. The average screening-questionnaire score fell from 10.10 at the start to 1.42 after the intervention. Participants rated the diet’s ease at 5.74 and its utility at 8.42 on the study’s rating scales; the authors noted that the ease rating reflected some difficulty making the change.

Depression scores were lower during the low-UPF period on three different mood rating score questionnaires:

• PHQ-9: 5.53 versus 8.68
• The Montgomery–Åsberg Depression Rating Scale: 8.05 versus 18.9
• Quick Inventory of Depressive Symptomatolog: 5.21 versus 8.89

Anxiety scores were also lower (4.63 versus 7.37). The statistical analysis suggested that the differences in symptom scores were unlikely to be explained by chance alone. However, only 19 people completed the study and are therefore preliminary findings that need confirmation in larger studies. It doesn’t yet settle whether reducing UPFs itself improves depression.

What the study did not show

• That reducing UPFs is an effective treatment for depression: Each participant tried both diets, with the order decided at random. This helps make the comparison fairer because people’s symptoms are compared with their own symptoms during the other diet. However, only 19 people completed the study; participants knew which diet they were following, and the main aim was to test whether the dietary change was manageable (feasibility and acceptability). The symptom improvements are encouraging, but larger studies specifically designed to test treatment benefits are needed to confirm them.
• Why depression symptoms were lower during the low-UPF diet: Changing the amount of ultraprocessed food someone eats may also change their intake of calories, fibre, sugar, fat and other nutrients, depending on what they eat instead. The study could not separate these changes from the effects of food processing itself. It also did not establish that additives or any other individual ingredient affected depression symptoms.
• That all UPFs have the same effect: UPFs are a broad category with foods varying in their ingredients and nutritional profiles. The study examined a broader dietary change rather than testing individual foods. It therefore cannot identify which products, if any, contributed to the symptom differences or whether reducing just one type of food would produce similar results.
• That the improvements would last or that diet could replace existing care: The study didn’t establish whether symptoms would remain lower over the longer term or whether people could maintain the dietary change. Participants were asked to keep their medication and therapy unchanged, so the trial didn’t test replacing these treatments with diet. Dietary intake was also reported through a questionnaire, leaving uncertainty about exactly what participants ate and how much their intake changed.

How the research was done

• Sample: 20 adults aged 18–80 with a primary diagnosis of depression, a PHQ-9 score of at least 5, high reported consumption of highly processed foods, and at least one self-reported metabolic abnormality. Nineteen completed the study.
• Data: Participants reported their consumption using an adapted screening questionnaire. Ease and utility were rated by participants.
• Primary outcomes & how measured: Feasibility through recruitment, completion and reduced questionnaire scores for UPF consumption; acceptability through ease and utility ratings. Depression and anxiety scales were exploratory outcomes.
• Confounding variables controlled for: The symptom models accounted for baseline mood score, study period and intervention sequence, and for repeated measurements within participants. Participants were asked not to change medication, therapy, exercise or sleep during the study; the intervention was not blinded.
• Design: Open-label, randomised-order crossover pilot trial comparing a usual-diet period with a low-UPF period. The main article reports that the study was conducted from June 2024 to June 2025, which is the study’s conduct window, not each participant’s follow-up duration.

EUFIC resources available

Are all ultra-processed foods bad for you? — explains why foods grouped as UPFs vary in nutritional value.

What is processed food? — explains food processing and the limits of broad processing categories.