Food and Mood: How What We Eat Influences Mental Health

Why Food and Mood Belong in the Same Conversation

When we think of mental health, we often picture therapy, mindfulness, or medication. But research increasingly shows that what we eat also has a profound effect on how we feel. This field — known as nutritional psychiatry — explores the fascinating relationship between diet, gut health, and mood.

From the nutrients that fuel our neurotransmitters, to the fibres that shape our gut microbiome, to the vagus nerve that connects brain and body, our food choices may influence not only our long-term brain health but also our day-to-day emotions.

In previous articles, I’ve written about how foods and habits reduce brain inflammation, how dementia develops long before symptoms appear, and 14 nutrients essential for brain health. This article builds on those ideas — zooming in on how food can directly shape our mental wellbeing.

Neurotransmitters: The Brain’s Chemical Messengers

Our moods, energy levels, and even ability to concentrate are largely shaped by neurotransmitters — chemical messengers that allow nerve cells to talk to each other. Without them, the brain couldn’t send or receive signals, and our bodies simply wouldn’t function.

Scientists have identified over 100 neurotransmitters, each with its own role. Some excite the brain (helping us think, learn, and remember), while others calm it down (reducing stress and anxiety). A healthy balance between these chemicals is essential for stable mood and mental wellbeing.

Here are a few of the most important for mood and mental health:

• Serotonin – often called the “happiness chemical.” It regulates mood, appetite, and sleep. Interestingly, around 90–95% of serotonin is produced in the gut, influenced by gut bacteria.

• Dopamine – linked to motivation, focus, and the brain’s reward system. It plays a key role in pleasure and learning.

• GABA (gamma-aminobutyric acid) – the brain’s main calming neurotransmitter. It reduces stress and anxiety and helps with sleep.

• Norepinephrine – helps with alertness, focus, and the body’s stress response (“fight or flight”).

• Glutamate – the most common excitatory neurotransmitter, essential for memory and learning.

• Acetylcholine – important for memory, learning, and muscle control.

Because neurotransmitters are built from nutrients in food, what we eat directly influences how well they are produced. For example:

• Tryptophan (from turkey, eggs, legumes, nuts, seeds) is the raw material for serotonin.

• Tyrosine (from poultry, dairy, beans, fish) is needed for dopamine.

• B vitamins, zinc, and magnesium act as “cofactors” — without them, neurotransmitter production slows down.

• Fermented foods like kefir, sauerkraut, and kimchi support the gut microbes that influence serotonin and GABA.

When neurotransmitters fall out of balance, mood disorders such as depression, anxiety, or even conditions like ADHD and Parkinson’s disease can appear. That’s why nutrition — alongside exercise, sleep and stress management — is such a powerful way to support mental health.

The Fibre Connection: Feeding the Gut, Calming the Mind

Dietary fibre isn’t just important for digestion — it may be vital for mental health. When gut bacteria ferment fibre, they produce short-chain fatty acids (SCFAs) such as butyrate, acetate, and propionate. These molecules:

• Strengthen the gut barrier (reducing “leaky gut”)

• Lower inflammation throughout the body

• Send signals through the bloodstream and the vagus nerve that may influence mood and cognition

According to research highlighted by ZOE, people who eat a wide variety of fibre-rich foods often report better mood stability and reduced risk of depression. Vegetables, fruits (including berries), legumes, nuts, seeds, and whole grains are all powerful mood foods.

The Vagus Nerve: A Superhighway Between Gut and Brain

The vagus nerve is a long cranial nerve that connects the gut and other organs directly to the brainstem. Think of it as a “bi-directional superhighway”:

• Signals from the gut (about nutrient status, microbial activity, inflammation) travel to the brain.

• Signals from the brain (stress, relaxation, emotional state) travel to the gut.

Animal studies show that if the vagus nerve is cut, the mood-related effects of the gut microbiome disappear — underscoring its importance. Beyond food, practices like deep breathing, meditation, humming, singing and even cold exposure can strengthen “vagal tone,” potentially enhancing gut–brain communication.

Food and Mood: The Mechanisms

Scientists describe several overlapping ways diet affects mental health:

1. Nutrient supply — amino acids, vitamins, and minerals are building blocks for neurotransmitters.

2. Microbiome balance — fibre and fermented foods increase microbial diversity, which supports resilience and mood regulation.

3. Inflammation control — diets high in ultra-processed foods, refined sugars, and trans fats increase inflammation, which is linked to depression and anxiety.

4. Neuroplasticity — certain nutrients and dietary patterns support BDNF (brain-derived neurotrophic factor), crucial for learning and mood resilience.

5. Blood sugar stability — balanced meals with protein, fibre, and healthy fats help prevent mood swings tied to glucose spikes and crashes.

Psychiatrist Dr. Drew Ramsey, a leader in nutritional psychiatry, describes nine mechanisms of how food impacts mental health, from providing essential nutrients to shaping the microbiome and reducing inflammation. He emphasises a “brain food” diet rich in:

• Seafood (omega-3s for mood and brain function)

• Leafy greens (folate, magnesium, antioxidants)

• Nuts and seeds (healthy fats, minerals)

• Beans and legumes (fibre, B vitamins, plant protein)

• Fermented foods (supporting gut microbiome diversity)

He also highlights the psychological side of eating: food as empowerment, self-care, and connection — factors that matter just as much for mental wellbeing as nutrients.

Practical Tips: Eating for Better Mood

If you’d like to support your mental wellbeing through food, here are a few practical starting points:

• Add more fibre: aim for 30g per day from varied sources.

• Choose protein at each meal: eggs, fish, legumes, whole grains, nuts, seeds.

• Eat more omega-3s: salmon, sardines, mackerel, walnuts, chia, flax, hemp.

• Incorporate fermented foods: kefir, yoghurt, sauerkraut, kimchi.

• Limit ultra-processed foods, sugar and artificial sweeteners. Ultra-processed foods and added sugars are strongly linked to inflammation and blood sugar spikes. Artificial sweeteners don’t raise blood sugar directly, but in some people they may trigger insulin release, may affect gut microbiome, and appetite regulation. The evidence is mixed and depends on the type of sweetener and the individual.

• Support vagal tone: deep belly breathing, meditation, humming, singing, mindful eating.

The Bottom Line

Food won’t replace therapy or medication when they’re needed, but it can be a powerful, accessible tool for supporting mood and mental health. By nourishing our gut microbiome, stabilising blood sugar, reducing inflammation, and supplying the brain with the raw materials it needs, diet becomes one of the most direct ways we can influence how we feel — every single day.

The next time you’re choosing a meal, remember: you’re not just feeding your body — you’re feeding your mind, too.

If you want to improve your nutrition, want to improve your health and don't know where to start, don't hesitate to reach out to me for personalised nutrition counselling and health coaching at info@katrinpeo.com.