Food & Nutrition That Supports Mental Health by Mack Bruce

‘You are what you ingest’—a reminder many factors influence mental health; however, food, nutrition and mental health remain central contributors to emotional stability and overall brain function, intersecting with one another in multidirectional ways. Certain foods or dietary patterns may have notable effects on glycaemia, immune activation, and the gut microbiome, thereby influencing the relationship between food and mood. Epidemiological research has observed that adherence to healthy or Mediterranean dietary patterns—characterized by high consumption of fruits, vegetables, nuts, and legumes; moderate consumption of poultry, eggs, and dairy products; and only occasional consumption of red meat—is correlated with a reduced risk of depression, although this association is complicated by the potential for reverse causality between diet and mental health (Firth et al., 2020). Dietary patterns influence mental health and overall well‑being via anti‑inflammatory, antioxidant, neurogenic, microbiome‑mediated, immune‑modulating, and epigenetic pathways. These patterns shape brain composition, structure, and function, as well as endogenous hormones, neuropeptides, neurotransmitters, and the microbiota–gut–brain axis, therefore modulating stress, inflammation, and cognitive resilience. Targeted supplementation with micronutrients and macronutrients can confer further benefits owing to their diverse biological functions (Muscaritoli, 2021). Stated succinctly, food, nutrition, and mental health share bidirectional relationships that cumulatively influence overall mental health and general well‑being.

Diet & Mental Health Outcomes

Depression and anxiety are among the most common mental health conditions globally and are leading contributors to disability, and beyond diagnosed disorders, subclinical symptoms of these conditions affect the well‑being and functioning of a large proportion of the population. Specific foods and dietary patterns have notable effects on glycaemia, immune activation, and the gut microbiome, thereby influencing the relationship between food and mood. Epidemiological research indicates an adherence to healthy or Mediterranean dietary patterns—typified by high consumption of fruits, vegetables, nuts, and legumes; moderate consumption of poultry, eggs, and dairy products; and only occasional consumption of red meat—is linked to a reduced risk of depression, although this correlation is complicated by the potential for reverse causality between diet and mental health. Changes in food choices or preferences caused by psychological states—such as seeking “comfort foods” during low mood or experiencing appetite changes under stress—are typical human experiences. The relationships between nutrition and longstanding mental illness are further complicated by barriers to maintaining a healthy diet, which disproportionately affect people experiencing mental illness and include social and environmental determinants of health as well as the appetite‑inducing effects of psychiatric medications. 

The consumption of highly refined carbohydrates increases the risk of obesity and diabetes—conditions associated with a higher likelihood of developing depression. High‑calorie meals rich in saturated fat also stimulate immune activation, which heightens depressive risk. In contrast, dedication to Mediterranean dietary habits has manifested reduction of inflammatory markers in humans and is associated with a lower risk of depression (Firth et al., 2020). Consuming high‑quality foods rich in vitamins, minerals, and antioxidants supports brain function and protects against oxidative stress—cellular damage caused by free radicals generated during normal metabolic processes. Diets high in refined sugars, conversely, impair insulin regulation and promote inflammation and oxidative stress. Numerous studies have found correlations between high intake of refined sugars, compromised cognitive functioning, and worsening symptoms of mood disorders such as depression (Selhub, 2022). Diet, together with genetic factors and exposure to antibiotics, plays a central role in shaping the diversity, relative abundance, and functionality of the gut microbiome (Firth et al., 2020). Psychiatry is increasingly recognizing the complex relationships between what individuals ingest, how they feel, how they behave, and the microbial communities that inhabit the gut. ~90–95% of the body’s serotonin is produced in the gastrointestinal tract, containing roughly one hundred million neurons. Although peripheral serotonin does not cross the blood–brain barrier, the gut’s neural, immune, and microbial signaling pathways help explain why digestive processes influence emotional regulation. Furthermore, the activity of these neurons and the production of neurotransmitter‑related metabolites are strongly shaped by the billions of beneficial bacteria that compose the intestinal microbiome (Selhub, 2022).

The neurocognitive consequences of the Western diet, and the potential mediating role of low‑grade systemic immune activation, may arise from a compromised mucus layer with or without increased epithelial permeability. This reduction in gut‑barrier function—often referred to as a ‘leaky gut’—is linked to a dysfunctional microbiome resulting from diets low in fibre and high in saturated fats, refined sugars, and artificial sweeteners. Contrastingly, diets rich in fibres, polyphenols, and unsaturated fatty acids promote microbial taxa capable of metabolising these substrates into anti‑inflammatory compounds such as short‑chain fatty acids, while reducing the production of secondary bile acids and p‑cresol. 

Research has illustrated ingestion of probiotics targeting the gut microbiome can alter neural responses during tasks involving emotional attention and may even reduce depressive symptoms in some individuals. Diet exerts an essential influence on mental health outcomes and overall well‑being through metabolic, inflammatory, and microbiome‑mediated pathways (Firth et al., 2020).

The Effects of Nutrition on Mental Health

Nutrition is a key determinant of mental health and overall well‑being. Healthy nutrition is vital for maintaining normal bodily functioning and preventing or mitigating dysfunctioning induced by internal or external influences. Nutritional deficiencies often cause hampered functioning and, conversely, nutritional intake at recommended levels can continue or enhance bodily functioning. Studies increasingly show that diet and nutrition play critical roles not only in physiology and body composition, but also have notable effects on mood and mental well-being. In a 6‑week double‑blind randomized placebo‑controlled clinical trial involving academic personnel aged 18–60 who were experiencing stress, 93 participants were assigned to one of three groups: a fish‑oil treatment group (n = 16), an olive‑oil placebo group (n = 14), and a non‑blinded no‑treatment group (n = 63). The study found a significant reduction in perceived stress in the fish‑oil group compared with both the placebo group and the no‑treatment group. In a 16‑week placebo‑controlled trial involving subjects aged 15–40 with recent‑onset schizophrenia‑spectrum disorders (n = 46) or bipolar disorder (n = 4) and current psychotic symptoms, 50 participants receiving risperidone were randomized 1:1 to adjunctive n‑3 PUFAs (polyunsaturated fatty acids) (n = 25) or placebo (n = 25). The active n‑3 PUFA group demonstrated substantial reductions in depression–anxiety symptoms compared with the placebo group. Another example is a 6‑month randomized, double‑blind, placebo‑controlled trial involving adults aged ≥65 years with probable mild cognitive impairment. 46 participants were randomized 1:1 to receive either a combination of omega‑3 and omega‑6 PUFAs with antioxidant vitamins (alpha‑tocopherol, gamma‑tocopherol, and vitamin A) (n = 23) or a placebo (n = 23). The study reported significant improvements in functional capacity and cognitive performance in the supplementation group compared with the placebo group.

The data supports a positive role for particular nutrients in preserving healthy cognitive function and mental well‑being, in part through their modulation of neuroinflammation. These findings underscore the importance of incorporating nutrient‑dense foods into a balanced and varied diet as part of a healthy lifestyle. This is relevant when considering cognitive aging, as the brain is highly susceptible to the cumulative effects of lifelong stressors and may benefit from targeted nutritional support (Muscaritoli, 2021).