We are what we eat - furthering our understanding of nutrition to optimize mental health

Growing evidence suggests that what we eat influences not just our physical health but also our mood, emotions, and overall well-being. Dietary changes such as reducing ultra-processed food intake and eating more fruits and vegetables, as well as taking certain nutritional supplements, have been associated with improvements in depression and other mental health problems in adults and with a healthier start to life for children. These benefits are increasingly tied to specific brain regions involved in eating behavior, social influences on what and how people eat, and the impact of the gut microbiome on immune, metabolic, and neural pathways.

“There is growing knowledge of the connection between nutrition, dietary patterns, and many aspects of psychological, cognitive, and behavioral functioning. We now understand from a robust evidence base that nutrition and dietary intake patterns can influence what we think, feel, and experience, including our mental health outcomes,” said Ephi Morphew-Lu, a clinical nutritionist who cofounded and directs the Center for Nutritional Psychologyopens in new window, a nonprofit dedicated to developing the scientific discipline focused on the link between diet and psychological well-being.

More than half of the calories Americans consume—and more than 60% consumed by children and teens—come from ultra-processed foods, highly engineered foods made mostly from refined ingredients and additives (“Ultra-Processed Foods and Human Health,” The Lancet, 2025opens in new window). These products are increasingly linked with poor mental health outcomes, suggesting dietary changes could give the nation’s mental health a big boost (Williams, A. M., et al., Ultra-Processed Food Consumption Among Youth and Adults: United States, August 2021–August 2023, NCHS Data Brief 536, 2025opens in new window). Two interrelated fields are emerging to support such a shift: nutritional psychology and nutritional psychiatry, with the latter focusing on the biological basis of nutrition and mental illness.

Researchers in both fields are developing guidelines and interventions to optimize nutrition for mental health. Despite structural barriers in the broader food and health care systems, clinicians also have an important role to play.

“Clinicians don’t need to be nutrition experts, but they should understand the evidence well enough to integrate it into their clinical work and help patients make informed choices,” said Julia Rucklidge, PhD, a clinical psychologist who directs the Te Puna Toiora Mental Health and Nutrition Research Labopens in new window at the University of Canterbury in New Zealand.

Many of the same foods known to support general health also promote healthy brain function. Diets high in fruits and vegetables, healthy fats, and minimally processed foods are linked to a range of positive mental health outcomes, including improvements in depression, well-being, and psychological distress (Lassale, C., et al., Molecular Psychiatry, Vol. 24, No. 7, 2019opens in new window; Theeraoat, P. T., et al., British Journal of Health Psychology, Vol. 30, No. 3, 2025opens in new window; Gillespie, K. M., et al., International Journal of Environmental Research and Public Health, Vol. 22, No. 7, 2025opens in new window).

The vitamins and minerals found in whole foods support the critical function of enzymes, which catalyze chemical reactions throughout the body, including those that fuel the brain’s neurotransmitters. When nutrients are lacking, these processes suffer. For example, iron is needed to convert the amino acid tyrosine into dopamine; when iron levels are low, dopamine can also drop, affecting concentration and motivation.

Research increasingly links gut health to reduced inflammation and improved functioning across many body systems, including the nervous system. Eating a variety of plants supports a healthy gut microbiome because each plant contains different polyphenols, chemicals that nourish beneficial gut bacteria. Gut health expert Tim Spector, PhD, of King’s College London, suggests eating a high-fiber diet with around 30 different plants per week (this includes fruits and vegetables but also grains, nuts, spices, and more).

“Keeping the messaging simple can help break down barriers for clients,” Rucklidge said. “It doesn’t matter which real foods you eat—just eat [minimally processed, whole] foods, and make sure there’s a great variety of them.”

The modern science of nutrition and mental health began with a simple observation: Countries that eat more fish tend to have lower rates of depression (Hibbeln, J. R., The Lancet, Vol. 351, No. 9110, 1998opens in new window). Since then, a growing evidence base—largely driven by research from the United Kingdom, Australia, and Brazil—has shown that nutrition, physical activity, and the body’s underlying metabolic and inflammatory processes are all critical for mental health.

Psychiatric epidemiologist Felice N. Jacka, PhD, founder and director of the Food & Mood Centre at Deakin University in Victoria, Australia, established the International Society for Nutritional Psychiatry Researchopens in new window in 2013 and conducted some of the first studies linking diet quality to mental health in children, adolescents, and adults. Her team’s work has led to the inclusion of unhealthy diet (defined as lacking essential foods and nutrients and high in ultra-processed foods) as a mental health risk factor in more than 130 high-level policy documents around the world, including the latest World Mental Health Reportopens in new window from the World Health Organization. They have also helped develop clinical guidelines on using lifestyle interventions to treat major depressive disorder (The World Journal of Biological Psychiatry, Vol. 24, No. 5, 2023opens in new window).

Another key effort linking nutrition and mental health comes from the Center for Nutritional Psychology (CNP), a San Jose, California–based nonprofit dedicated to systematically integrating the psychological and nutritional sciences. The CNP’s international team of psychologists, dietitians, and other experts identifies, reviews, summarizes, and catalogs publications in its online research libraryopens in new window. They are also outlining barriersopens in new window to progress in nutritional psychology and building an encyclopediaopens in new window of terminology and methodological frameworksopens in new window to bridge the two fields. The latter includes illuminating the role of cognition, emotions, perceptions, relationships, and other factors in dietary behavior, as well as the application of psychological models such as self-determination theory and attachment theory.

The CNP is using this extensive review to develop assessment tools for trained nutritional psychology professionals in both educational and clinical settings. As an APA-approved continuing-education sponsor, the CNP has created 11 online coursesopens in new window, with a clinically focused “micro degree” in nutritional psychology soon launching to provide certification in this emerging field.

To date, dietary interventions for depression provide the strongest experimental evidence for the role of nutrition in mental health. In the Food & Mood Centre’s SMILES trial (Supporting the Modification of Lifestyle in Lowered Emotional States), adults with moderate to severe major depressive disorder who received nutritional counseling for 12 weeks had more improvement in symptoms and a greater likelihood of remission than adults in the control group, who received a social support protocol following the same schedule as the nutritional counseling (Jacka, F. N., et al., BMC Medicine, Vol. 15, No. 23, 2017opens in new window). Meta-analyses of randomized controlled trials and cross-sectional studies indicate that following a Mediterranean or similar diet reduces depressive symptoms and risk, while diets high in ultra-processed foods increase risk (Bizzozero-Peroni, B., et al., Nutrition Reviews, Vol. 83, No. 1, 2025opens in new window; Firth, J., et al., Biopsychosocial Science and Medicine, Vol. 81, No. 3, 2019opens in new window; Firth, J., et al., World Psychiatry, Vol. 19, No. 3, 2020opens in new window).

Even a simple change—taking daily nutritional supplements—can make a difference. Rucklidge and her colleagues found that adults who took Daily Essential Nutrients from Hardy Nutritionals, a broad-spectrum mix of vitamins and minerals (micronutrients) designed to fill common nutrient gaps, had better improvement in depression and anxiety symptoms than those who took a placebo (Journal of Affective Disorders, Vol. 339, 2023opens in new window).

The same supplements used in that study may reduce mental health risks for pregnant women and improve birth outcomes. In a small trial known as NUTRIMUMopens in new window, Rucklidge found that women with perinatal depression who took the supplements during pregnancy had reduced depression symptoms. Compared with women taking antidepressants, their infants also had a better start to life, including longer gestational age, lower rates of infant resuscitation, and healthier birth lengths (BJPsych Open, Vol. 10, No. 4, 2024opens in new window; Journal of Clinical Psychopharmacology; Vol. 45, No. 1, 2025opens in new window).

“We know that these infant health outcomes can be risk factors for mental health disorders in children,” Rucklidge said. “They seem to have been mitigated with micronutrients, which has never been observed with SSRIs.” (See recent guidelines for micronutrients and mental illness in both adults and children: Sarris, J., et al., The World Journal of Biological Psychiatry, Vol. 23, No. 6, 2022opens in new window; Journal of Child Psychology and Psychiatry, Vol. 66. No. 4, 2025opens in new window).

Broad-spectrum micronutrient supplements might also reduce symptoms of attention-deficit/hyperactivity disorder (ADHD), including hyperactivity, impulsivity, and attention problems (British Journal of Psychology, Vol. 204, No. 4, 2014opens in new window). Research led by clinical psychologist Jeanette Johnstone, PhD, of Oregon Health & Science University, points to the gut microbiome as a pathway for those improvements. Johnstone and her colleagues found that children with ADHD who took daily broad-spectrum micronutrient supplements had changes in fecal bacteria not observed in the placebo group—and that those changes were tied to improvements in ADHD symptoms (Gut Microbes, Vol. 17, No. 1, 2025opens in new window).

Rucklidge has launched a new study to test whether combining nutritional supplements and psychological interventions could offer a synergistic effect for patients. Her team’s Mindfulness and Micronutrients trial explores whether the combination could better help children with emotional dysregulation than either intervention alone.

“The idea is that a well-nourished brain may [improve the effectiveness of] psychotherapy,” Rucklidge said.

In addition to taking supplements and improving overall diet by eating more whole foods, research shows that consuming fermented foods can have a positive impact on the brain—again linked to changes in gut health. In one study from the Food & Mood Centre, healthy women were given either a small daily serving of fermented dairy with probiotic bacteria or a placebo for 8 weeks. Women who consumed fermented dairy had a greater rise in glutathione, the brain’s antioxidant, than those in the control group. They also had increased volume in the hippocampus and greater functional connectivity between the hippocampus and the frontal lobe, which correlated with a rise in fecal probiotic bacteria (publication in press).

Jacka’s team has now developed a digital intervention for improving diet and gut health during pregnancy, which is being tested in a randomized controlled trial of approximately 1,000 mother-child pairs. Outcomes measured will include peri- and postnatal depression; infant well-being, behavior, and neurological development; and several markers of gut health.

Early evidence suggests that metabolic and dietary interventions might also reduce symptoms of serious mental illness. Shebani Sethi, MD, a clinical associate professor and founding director of the Metabolic Psychiatry Clinicopens in new window at Stanford University, pilot tested a 4-month metabolically targeted high-fat, low-carbohydrate (ketogenic) diet intervention to supplement psychiatric care in 21 adults with schizophrenia or bipolar disorder. On average, participants had a 31% improvement on the Clinical Global Impression scale, a standardized tool that gives a snapshot of patient mental health and symptom severity. The trial also reversed metabolic syndrome (a combination of weight, blood sugar, and cholesterol problems) in all participants who had it at baseline, which was associated with an average of 10% body weight loss, and improved several key metabolic markers (Psychiatry Research, Vol. 335, 2024opens in new window).

Sethi is now continuing more research on dietary interventions, including looking at measurements of heart rate variability, exercise, and sleep patterns. The ketogenic diet intervention is intended to complement—not replace—treatment with psychiatric medications, but more controlled research is needed to fully understand its risks and benefits. It may also help reduce metabolic side effects of medications, such as weight gain, high blood pressure, and pre-diabetes, making it easier for patients to continue medications they might otherwise have stopped.

“We really want to improve the quality of life for patients by turning this science into care as quickly as possible,” Sethi said.

As evidence for nutrition’s role in mental health grows, providers and organizations are translating science into practice across a variety of settings. Mihaela Beloreshka, PhD, a health psychologist and certified nutritional therapist based in Sofia, Bulgaria, often sees patients whose needs aren’t fully met by dietitians, gastroenterologists, or traditional psychotherapy.

Many of Beloreshka’s clients struggle with some combination of orthorexia (a pattern of rigid, anxiety-driven “healthy eating” that can interfere with daily life, though not a formal Diagnostic and Statistical Manual of Mental Disorders diagnosis), emotional or stress-related eating, and irritable bowel syndrome (IBS). She begins with psycho-nutritional education, teaching clients about the gut-brain connection and how fear of food-related symptoms or restrictive eating can actually trigger IBS symptoms (Alimentary Pharmacology and Therapeutics, Vol. 59, No. 4, 2024opens in new window). Her approach blends somatic techniques for nervous system regulation with behavior-change tools, such as food diaries that track how sleep, mood, and stress relate to eating.

Beloreshka also leads cooking workshops, which can further boost mental health by providing opportunities for social connection. “This adds a social bonding and community component, as well as the chance to have a relaxed and positive experience around food,” she said.

In Los Angeles, David Wiss, PhD, a registered dietitian and researcher whose work bridges public health, mental health, and nutrition, uses nutritional psychology interventions to support patients with substance use disorders, ultra-processed food addiction (not an official diagnosis), and other concerns.

“Because food can be a source of reward, it’s wise to consider whether it’s being used as a form of self-medication to reduce negative mood or manage difficult emotions,” he said.

Wiss combines lab testing with counseling to support recovery. Clinical tests help identify nutrient deficiencies, genetic vulnerabilities, and other factors that may affect treatment progress. When counseling patients, Wiss starts by taking an inventory of their beliefs about food and body, then uses dialectical behavior therapy and other approaches to help individuals build their own values-based approach to eating.

Reducing ultra-processed food intake and eating higher-quality foods can improve mental health for many people, but it can be problematic for patients with restrictive eating disorders such as anorexia nervosa. Nutritional psychology practitioners typically screen for a history of disordered eating during intake. They also monitor warning signs—such as rapid weight loss or unhealthy cognitive patterns around food and weight—and refer patients to specialized care when needed.

At the organizational level, the U.K.-based charity Think Through Nutritionopens in new window is using nutritional psychology to boost mental and behavioral health in prisons, schools, workplaces, and beyond. The charity partners with government and community organizations to augment their services with in-person or digital interventions.

In a juvenile detention setting, participants randomized to take dietary supplements committed 37% fewer violent offenses than those given a placebo (Gesch, C. B., et al., British Journal of Psychiatry, Vol. 181, No. 1, 2002opens in new window). In a women’s prison, those who took supplements for up to 9 months reported improvements in mood, energy, and self-worth (Nutrition at Eastwood Park: Impact Report, Think Through Nutrition, 2020opens in new window).

“When people are better nourished, we often see calmer behavior, improved focus, and a greater capacity for positive change,” said Tahani Saridar, Think Through Nutrition’s CEO.

Among mental health professionals surveyed by the CNP, 98% discuss nutrition in their practice, but the majority lack formal training on the link between nutrition and mental health (Towards Integration of the Psychological and Nutritional Sciences: Insights From a Cross-Sectional Survey of Mental Health and Nutrition Professionals, Preprints.org, 2025opens in new window). A similar gap exists among psychiatrists (who were not included in the survey), Jacka said, pointing to the need to integrate nutritional training into formal training for physicians and other care providers.

“We’re still a long way off from being a standard part of clinical practice, in large part because most health practitioners get just a few hours of nutrition training throughout their whole degree,” she said.

For now, continuing-education programs can provide training for providers seeking to expand their knowledge of nutrition and mental health.

“Psychologists may worry about stepping outside of their scope of practice, but there are enough educational opportunities out there to start lessening the fear of talking about food,” Rucklidge said.

Research continues to expand, with both the CNP and ISNPR working to standardize methodology in their respective fields so that data can be pooled to draw broader conclusions (Stroebele-Benschop, N., et al., Behavioral Sciences, Vol. 15, No. 8, 2025opens in new window; Marx, W., et al., British Journal of Nutrition, online first publication, 2024opens in new window). At present, differences in supplement formulas and dietary assessment methods make it hard to compare results across studies.

Despite the mounting evidence for nutrition’s role in mental health, policy change remains challenging because of the strong influence of global food industries, Jacka said. To help drive farming practices that support improved brain health, she is working to highlight the link between soil health, gut health, and mental health, including through her work with the World Economic Forum (Transforming the Global Food System for Human Health and Resilience, World Economic Forum, 2023opens in new window).

“It’s really important for academics, nonprofits, and governments to stay up to date with this science,” Beloreshka said. “In the midst of a mental health crisis, we have very promising data that we can use to safely make changes across society.”