Mood

Mood is shaped by many things — sleep, relationships, work, hormones, brain chemistry — and a growing body of research has put diet on the list of factors worth attending to. The field of nutritional psychiatry has begun mapping how what you eat affects the gut microbiome, inflammatory state, and the availability of nutrients the brain uses to make neurotransmitters, each of which can influence mood.

A useful frame: food influences mood through four main pathways. The gut-brain axis — where gut microbes and enteroendocrine cells produce signaling molecules and metabolic precursors that affect the central nervous system. (Most of the body's serotonin is produced in the gut, but this peripheral serotonin doesn't cross the blood-brain barrier — the gut-brain link runs through tryptophan metabolism, short-chain fatty acids, the vagus nerve, and immune signaling instead.) Blood sugar stability — where refined-carb-driven glucose swings can contribute to mood changes later in the day. Systemic inflammation — where high-inflammation diets have been associated with higher rates of depression. And nutrient availability — omega-3 fats, B vitamins, magnesium, and tryptophan are all involved in mood regulation.

What tends to lower mood

Ultra-processed diets — high in refined sugar, refined grains, and added fats — have been associated with higher rates of depression in observational studies. Alcohol is a depressant; mood effects often include the day of drinking and can extend into the next day or two via degraded sleep. Heavy caffeine intake can amplify anxiety, and the afternoon crash often produces a noticeable mood dip. In some people with diagnosed food sensitivities (celiac disease, non-celiac gluten sensitivity, lactose intolerance, or cow's-milk-protein reactions), removing the triggering food has been reported to improve mood symptoms.

What tends to support mood

A "Mediterranean-style" pattern — vegetables, legumes, whole grains, olive oil, fish, moderate dairy, minimal processed food — is the most-studied dietary approach for mood, including in the SMILES randomized trial. Omega-3-rich foods (fatty fish, walnuts, flaxseed) and prebiotic foods that feed the gut microbiome are common starting points. Diet does not replace clinical care for depression or anxiety, but it can be a useful adjunct alongside sleep, movement, social connection, and treatment.