Food for your mood
by Rosemary Martin, Registered Dietitian
We often talk about awareness, stigma, and different ways to support mental health, but how often does the conversation include nutrition? Most of us are aware that what we eat has a major impact on our physical health, including the risk of cardiovascular disease, obesity, high blood pressure, and type 2 diabetes. Yet the impact of diet on another vital organ, our brain, remains largely unrecognised.
Observational research has long suggested that dietary patterns play a role in the risk of mood disorders. Although there are cultural differences in what is considered the “optimal” diet, the consensus points towards whole plant foods as being central. In contrast, the Western diet pattern high in meat and foods high in sugar, salt and saturated fat have long been shown to adversely affect mood and mental health outcomes
Fruit and vegetable consumption is especially protective, with studies showing benefits for general mental health and wellbeing, stress, happiness, quality of life and for reducing the risk of depression and anxiety. There may be a dose effect, such that the more frequently fruits and vegetables are eaten, the greater the benefit. In addition, processed versions of fruit and vegetables, such as canned and juices, also appear to have a positive impact.
Dietary patterns and mental health outcomes
When it comes to dietary patterns, the strongest evidence points towards the Mediterranean diet. This includes a positive association between fish consumption and better mental health, in particular a lower risk of depression. Whether this relationship is causal, or a reflection of a healthier diet pattern is yet to be determined.
The Mediterranean diet has now also been shown in randomised controlled trials (RCT) to be an effective treatment for people with depression. The landmark SMILES trial was the first to demonstrate that dietary change, supported by a dietitian, significantly improved symptoms in people with moderate-to-severe depression. More recently, a 2019 randomised controlled trial showed that even a short, three-week dietary improvement reduced depressive symptoms in young adults. A 2019 meta-analysis pooling multiple intervention studies concluded that dietary improvement can be an effective add-on therapy for depression, especially when based on whole foods and guided by professionals. A more recent systematic review and meta-analysis of five RCTs confirmed that Mediterranean diet interventions, and therefore a greater emphasis on plants, significantly reduced depressive symptoms, particularly in young and middle-aged adults.
Meat consumption and mental health
There has been significant misinformation around the impact of meat consumption on mental health outcomes. Industry-funded studies have suggested that meat-free diets increase the risk of depression and anxiety. However, the methodologies have not been sufficiently robust to exclude reverse causation, i.e. it cannot take into account what came first — the mental health disorder or removing meat from the diet.
Studies that have taken into account diet quality have consistently shown that plant-based diets, including vegetarian and vegans diets, when centred on whole foods, are associated with positive impacts on mental health. This includes a lower risk of depression, anxiety and psychological distress.
An interesting randomised study was conducted by the Physicians Committee for Responsible Medicine for the company GEICO in the United States. This was a multi-centre workplace intervention conducted and included 292 participants across 10 corporate sites, who were overweight and/or had a history of type 2 diabetes. They were randomised to a low-fat vegan diet composed of fruits, vegetables, whole grains and legumes or to continue their usual diet for 18 weeks. The intervention group also had weekly support meetings. The results showed a significant improvement in mental health well-being, work productivity and reductions in depression and anxiety scores in those on the vegan diet.
How does what we eat impact our mental health?
Research is progressing into the underlying mechanisms.
The gut-brain axis, inflammation and oxidative stress, and neuroplasticity are increasingly recognised as pathways linking diet and mood. Higher fibre intake may be one of the key reasons for better mental health outcomes observed with healthy diet patterns. However, fibre supplementation in intervention studies does not appear to provide a benefit, suggesting that focus should be on whole foods and overall diet quality that will also provide higher intakes of other beneficial phytonutrients.
While this area of science is still young compared to research on diet and physical health, the direction is clear: what we eat matters for our mental health as well as our bodies.
A dietitian’s top tips for good mood food
1. Eat regularly
Aim for 3 meals and 2–3 snacks if hungry, starting with breakfast. Regular meals support blood sugar stability throughout the day and can reduce tiredness and irritability linked to low blood sugar.
2. Stay hydrated
Around 6–8 cups (1.5–2 L) of fluid daily is usually enough to support concentration, alertness, and bowel function. The quantity needed may vary between individuals and so checking that your urine colour is helpful to understand your hydration status; aiming for no darker than a light straw colour. Choose mainly water and other non-fizzy, non-alcoholic drinks. Limit caffeine to <3 drinks per day and fruit juice to <150 ml.
3. Nourish your gut
Due to the strong communication between our brain and our gut, supporting a diverse gut microbiome with fibre-rich, minimally processed plant foods will benefit both digestive health and mood.
4. Get your fibre
The UK recommendation is 30 g per day, yet most people average just 18 g. Boost your intake with whole grains, fruit, vegetables, legumes, nuts, and seeds. If you are increasing plants, and therefore fibre, do so gradually with plenty of fluids to reduce the risk of short-term discomfort.
5. Include whole grain carbohydrates
Whole grain carbohydrates are important for energy and nutrients including B vitamins and calcium. The brain uses carbohydrate as its main fuel source, so base meals around whole grain breads, brown rice, or wholewheat pasta.
6. Fill up on fruit and veg
Aim for a minimum of 5 portions (80 g each) of different fruits and vegetables daily. A varied, plant-based diet can easily meet this.
7. Choose healthy fats and proteins
By eating a plant-based diet you’ll naturally reduce saturated fat. Healthy fats come from avocados, nuts (especially walnuts), and seeds. Consider an algae-based omega-3 supplement for additional support. Plant proteins such as beans, lentils, tofu and tempeh should be included with most meals.
8. Look after key nutrients
Iron, folate, selenium, and B vitamins have all been linked with mood regulation. A balanced, plant-based diet provides most of these, but supplementation may be needed in some cases (e.g. B12 and omega-3).
9. Limit ultra-processed foods
Highly processed foods high in sugar, fat, and salt are associated with poorer mental as well as physical health. A whole food plant-based diet helps naturally minimise these.
10. Combine with other lifestyle habits
Nutrition is just one piece of the puzzle. Spending time outdoors, moving regularly, resting, connecting with others, and practising mindfulness all support mental wellbeing.
All pillars of lifestyle medicine are important in supporting mental health and lifestyle interventions are now recognised as a key component of prevention and management of mental health disorders. However, neither nutrition nor lifestyle are a silver bullet for mental health concerns. If you or your patients are experiencing periods of low mood, depression, or anxiety, please seek appropriate medical support.
Further resources include the Food and Mood Centre and clinical guidelines on lifestyle medicine and major depressive disorder. Listen to Dr Ishani Rao on the In a Nutshell Podcast talking about mental health.