Older adults who ate less of two types of food groups were found to experience notable changes in their depression risk and symptoms, according to a new study.
Researchers at Deakin University and Monash University, in Australia, found that those over the age 70 who had a reduced consumption of ultraprocessed foods had a lower risk of experiencing depressive symptoms, while those who ate fewer inflammatory foods had less depressive symptoms.
The experts said that overall, higher quality diet was associated with a lower risk of depressive symptoms in older adults, regardless of genetic predisposition to the mental health condition or low-grade inflammation. The study was published in the journal Molecular Psychiatry in July.
"These findings add to mounting evidence that many ultra-processed foods aren’t great for our brains or our bodies, and it’s best to avoid them when we can," Susan Carnell, an associate professor of medicine at Johns Hopkins University, told Newsweek.
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What Are Ultraprocessed And Inflammatory Foods?
In the study, the researchers classed ultraprocessed foods based on the NOVA food classification system, which groups foods and drinks based on how much they have been processed.
Ultraprocessed foods include, but are not limited to, carbonated soft drinks, packaged snacks, chocolate, candies, ice cream, mass-produced packaged breads, pastries and buns, margarines and other spreads, breakfast cereals, certain meat and fish products and powdered or packaged ‘instant’ soups, noodles and desserts.
These are foods which are designed to be profitable and to have a lower shelf life, which often means they contain ingredients not typically found at home, such as chemical-based preservatives and sweeteners.
There has been increasing research indicating that ultraprocessed food could harm human health by potentially increasing risk of several health problems and even death, although more research still needs to be done to determine their impact. This is also not the first study to find that higher consumption of ultraprocessed food could impact mental health.
Carnell also noted that "not all ultraprocessed foods are equal," as, for example, "some whole-grain products and plant-based alternatives are classified as ultraprocessed foods, but these might not be as detrimental to health as other ultraprocessed foods like sugary drinks and confectionary."
Inflammatory food is a group of foods that are believed to trigger or worsen chronic low-grade inflammation in the body when consumed regularly. Inflammatory food would include ultraprocessed food, but also other things like refined carbohydrates, fried food and others.
The researchers calculated how inflammatory the participants' diets were based on the Dietary Inflammation Score, which scores diets based on how frequently a person consumes certain foods, and negative dietary scores are considered anti-inflammatory, while positive scores are considered inflammatory.
How Diet Affected Depression Risk
In a sample group of over 7,000 older adults, the researchers found that a higher consumption of ultraprocessed food, defined as at least four servings a day, was associated with a 12 percent higher rate of depressive symptoms. The experts followed the older adults for a median of 5.7 years.
Meanwhile, eating an anti-inflammatory diet was associated with a 7 percent lower risk of depressive symptoms compared to a pro-inflammatory diet.
Lead study author Belayneh Miteku, a PhD candidate at Deakin University, told Newsweek that pro-inflammatory foods and ultraprocessed foods "may affect mental health through several interconnected pathways, including gut microbiota disruption, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, oxidative stress, mitochondrial dysfunction and chronic inflammation."
"Low-quality diets, such as those high in refined carbohydrates, trans fats, and additives, increase levels of pro-inflammatory cytokines that can disrupt neurotransmitter systems, neurogenesis, and HPA axis regulation," he said.
The results were found regardless of genetics, which Dr Uma Naidoo, director of Nutritional and Metabolic Psychiatry at Massachusetts General Hospital, told Newsweek was the "most clinically interesting" finding, and said it supports "dietary counseling even in patients with a strong family history."
Although, it's important to note that the benefits in this study were "real but modest," Naidoo said. "You likely will not feel a dramatic change overnight, but good eating habits add up over time and also help your heart, brain, and overall health."
"This study was also limited to Australians of European descent, so it needs to be replicated in more diverse groups," Nicole Avena, a professor of neuroscience at the Icahn School of Medicine at Mount Sinai, told Newsweek.
The findings are notable though because "older adults have neurological vulnerabilities that may be important for mental health," Carnell said, noting that "depression is related to neurogenerative conditions like Parkinson’s and Alzheimer’s, and may be a precursor of some of these conditions."
She also said that "getting older is often accompanied by physical conditions and medication use, as well as life changes like bereavement, retirement and reduced social contact, which can challenge mental health."
Could Diet Also Affect Mental Health In Young People?
There have also been several similar studies suggesting that diet quality could influence depression in younger adults, but fewer testing the hypothesis in adolescents, Carnell said, adding that as depression in teenagers is "quite high, this could be an important research gap."
"I would expect the general relationship to hold in younger people," Avena said, pointing to the SMILES trial, where "adults with depression who improved their diet saw greater improvement in symptoms than those who received social support alone."
"That said, age likely affects how strong the effect is and which mechanisms matter most, so I wouldn't assume the exact numbers carry over," she added.
What Do The Findings Mean?
Miteku said the findings provide evidence that "dietary intervention can prevent late-life depression and support the strategy of using adherence to a healthy lifestyle as a complementary treatment option alongside standard care practices."
"This is about prevention and risk reduction, not a replacement for treatment," Avena said. "The effects are modest at the individual level, and the study used a symptom questionnaire rather than clinical diagnoses," she added but said she would "like to see diet become a routine part of the conversation about mental health in aging, rather than an afterthought."
Naidoo said that taking steps toward a "mood-friendly" diet are relatively "simple," and include filling half of your plate with vegetables and fruit, choosing whole grains, using olive oil as your main fat, cutting back on ultraprocessed foods, staying hydrated and eating fish, beans, lentils and nuts regularly.
She also said that while diet is "helpful," it is "not a substitute for medical care," and those who experience persistent sadness, low mood, loss of interest in things once enjoyed, trouble sleeping, low energy and other symptoms should consult their doctor.
Reference
Mengist, B., Davoodian, N., Lotfaliany, M. et al. (2026) Diet quality and depressive symptoms in older adults, assessing the effect modification by genetic predisposition and low-grade inflammation: a target trial emulation. Molecular Psychiatry. https://doi.org/10.1038/s41380-026-03762-6