Mental Health + Nutrition. What The Science Says

Mental health + nutrition. What the science says.

Food is recognised as a modifiable factor in the treatment and prevention of mental illness.

One of the most studied dietary patterns for mental health is the Mediterranean diet – rich in vegetables, fruits, whole grains, legumes, fish, and olive oil.

The SMILES trial found that participants with major depression who followed a Mediterranean-style diet experienced significantly greater improvements in mood than those receiving social support alone. After 12 weeks, 32% of the Mediterranean diet group were in remission from depression, compared to 8% in the control group.

Nutrients that support mental health

Several nutrients have been consistently linked with improved mental health outcomes:

Omega-3 fatty acids (fatty fish and algal oil) are associated with reduced symptoms of depression. Analysis shows omega-3 can be an effective additional treatment for major depressive disorder.
B vitamins, particularly B6, B9 (folate), and B12, support neurotransmitter creation and have been inversely associated with depression and cognitive decline (Yao Gao 2025).
Magnesium, found in leafy greens, nuts, and whole grains, has been linked to improved mood and reduced anxiety symptoms in multiple observational studies (Tarleton & Littenberg, 2015).

The brain requires nutrients to function

The brain is an energy intensive organ, using about 20% of the body’s energy. It depends on glucose, amino acids, fatty acids, vitamins, and minerals to produce neurotransmitters, regulate mood, and support brain function.

Amino acids from foods containing protein are used to create the neurotransmitters serotonin, dopamine, and GABA – all essential for mood.
B vitamins, magnesium, and zinc are involved in neurotransmitter creation.
Omega-3 fatty acids support neural membrane fluidity, which are critical for communication between brain cells.

Enhancing medication

Good nutrition can also make antidepressant medications more effective. For example:

Omega-3s can enhance the effects of SSRIs.

Blood sugar and mood

Frequent spikes and crashes in blood sugar can lead to:

Irritability
Anxiety
Fatigue
Difficulty concentrating

Balanced meals with complex carbohydrates, protein, and healthy fats help maintain stable energy and mood throughout the day.

The brain-gut connection

The connection between the gut and brain is now widely acknowledged and highlights how dietary choices affect mood and cognition.

The health of bacteria in the gut influences emotional regulation, stress response, and even the risk of developing psychiatric disorders such as depression and anxiety.

Dietary fibre is the fuel for the gut good bacteria. Fibre is unable to be digested in the stomach and small intestine, but when it enters the large intestine, the bacteria digest it to create molecules such as short-chain fatty acids, which help maintain good gut lining. Without the SCFAs, the gut lining can become compromised and contribute to inflammation.

In particular, fermentable fibres can influence biological pathways relevant to depression and anxiety through the gut-brain connection. The gut bacteria also influence serotonin (the feel-good neurotransmitter) by influencing the metabolism of tryptophan, which is required to make serotonin. Fibre can help steer tryptophan towards a more beneficial pathway.

The Food & Mood Centre conducted research which identified an inverse relationship between fibre intake and depression & anxiety symptoms.

Examples of fermentable fibres include: artichoke, asparagus, beetroot, celery, fennel, garlic, green peas, leek, onion, cabbage, spring onion, sweetcorn, apples, dates, grapefruit, nectarines, watermelon, baked beans, chickpeas, lentils, red kidney beans, soy beans, barley, bran, buckwheat, oats, rye, spelt, almonds, cashews, hazelnuts, linseeds and pistachios.

UK guidance is 25g-30g fibre per day. If you’re starting the journey, build up slowly to avoid digestive discomfort.

Ultra-processed foods and mental health risks

High consumption of ultra-processed foods has been linked with poor mental health outcomes. A 2022 study using data from over 10,000 adults in the U.S. found that those who consumed more ultra-processed foods were 80% more likely to experience mild depression and anxiety symptoms (Samuthpongtorn, C 2023).

Practical tips

Prioritise whole, nutrient-dense foods: a variety of fruits, vegetables, whole grains, and healthy fats.
Incorporate fermented foods: live/Greek yogurt, kefir, kimchi, and sauerkraut.
Limit sugar and refined carbohydrates: these can cause blood sugar fluctuations that affect mood, energy & concentration.
Be mindful of caffeine and alcohol: both can interfere with sleep and mood.