| Post published on June 27, 2022
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Why food has a bigger impact than you might think


It’s widely accepted that the foods we eat affect our physical health but we’re often not aware that they can also affect our mental health.

You know it only too well – when you feel sad, you reach for your favourite comfort food. The comfort it provides is often purely emotional but some foods may actually help you feel better.


Gut-brain connection

What you eat determines what gut bacteria you have in your intestines – some thrive on fibre, some on sugars, others on fats, processed foods or meat. All gut bacteria produce by-products of their metabolism and those tend to be absorbed by the gut wall. Bacteria can also alter how much is absorbed by the gut – making it either very tight or slightly leaky, which can be dangerous. Some gut bacteria can be downright harmful and fuel inflammation in the gut, which then sends signals to the immune system and the brain.

All this – bacterial by-products, molecules penetrating through the gut wall and immune system molecules – has a direct effect on your brain and scientists call this communication channel the gut-brain axis. It affects the production of the communication molecules in the brain – neurotransmitters.

Some neurotransmitters, such as serotonin or dopamine, make you feel good and you can increase their production with food. On the other hand, the wrong kinds of food hinder their production and can make you feel miserable.


Foods that affect the gut-brain axis

The foods that feed the good gut bacteria and stimulate your gut-brain connection the right way are whole foods rich in fibre and antioxidants, such as fruit and vegetables, wholegrains, pulses, nuts and seeds. These help to promote a balanced state in your brain, when enough feel-good neurotransmitters are produced over long periods of time. Research shows that eating a wholesome diet that supports beneficial gut bacteria may reduce anxiety, stress reactions and even resolve some temporary memory issues.

On the other hand, foods that feed the harmful gut bacteria have a negative effect on the gut-brain axis and include processed foods high in fat, sugar, salt, preservatives and food colourings, deep-fried foods and animal products. Sugary foods and drinks are also bad news because while they may give your brain a very quick dopamine hit, it doesn’t last as your body releases large amounts of insulin to bring your blood sugar levels down. This works a little too well so you end up with lower blood sugar levels, feeling tired, miserable and craving more sugar.

The bad gut bacteria, if they are fed often enough by the wrong kinds of food, can result in low mood, lack of energy, depressive symptoms and increased levels of stress hormones.


The good mood food

To make serotonin, the neurotransmitter that makes you feel good or even happy, your brain needs the amino acid tryptophan. This is a separate issue from the gut-brain axis – it’s about the building material for serotonin.

When your brain produces enough serotonin, you don’t just feel good, it also makes you more stress-resilient. So having plenty of tryptophan-rich foods in your diet can improve your mental health. These foods include nuts (almonds, cashews, walnuts and pistachios), seeds (pumpkin, sesame, sunflower and chia seeds), soya beans (edamame), tofu and tempeh, peas, beans, lentils, oats, wheat germ, bananas, spinach and other leafy greens.

To turn tryptophan into serotonin, your body also requires vitamins C, B6, folate, biotin, magnesium, zinc and omega-3 fats. And it just so happens that a healthy plant-based diet supplies all of these!


Fats for your brain

Your brain is mostly fat and you need good fats to keep it at its best. Choose nuts and seeds, nut butters, virgin olive oil and omega-3 fats. For your daily omega-3 dose, have a heaped tablespoon of ground flaxseed or chia seeds, a teaspoon of flaxseed oil, a couple of tablespoons of hemp seeds or a small handful of walnuts. Alternatively, you can also get your omega-3 dose from a supplement made from microalgae.



We tend to turn to caffeinated drinks more often when we’re tired of feel low because they give us an energy boost. However, coffee also makes you release an extra dose of stress hormones – that’s what makes you more alert but it can also make you feel anxious. Try to limit your coffee habit to three cups a day – research shows that’s a safe amount for healthy people.

Better yet is switching to tea because although it also contains caffeine, it has less than coffee and contains a substance called L-theanine – an amino acid that reduces anxiety and boosts your mood. Green tea is best because it has less caffeine than black tea but both are good sources of L-theanine.

Dark chocolate is another source of caffeine but it contains relatively small amounts. It can help lift your mood because cocoa stimulates the release of endorphins in your brain, also called ‘happy hormones’. It can trigger the release of dopamine, inducing pleasurable states of mind. Cocoa also contains anandamide – a special compound that produces blissful feelings – and tryptophan that you need to make serotonin. It has to be dark chocolate, 70 per cent at least, to be ‘strong’ enough in its effect and a few squares are enough. Eating the whole bar in one sitting would give you too much sugar and fat, so the key here is moderation.


A feel-good habit

Eating a wholesome plant-based diet, together with some physical activity, can work wonders for your mental health. It doesn’t mean you can’t have cake and chips, just don’t make them your everyday staple but have them as a treat once in a while.

It may take a few days for you to start feeling the effects of a gut-brain friendly diet but the more healthy the choices you make, the more you’ll feel your body and mind responding over time.


About the author
Veronika Prošek Charvátová
Veronika Prošek Charvátová MSc is a biologist and Viva! Health researcher. Veronika has spent years uncovering the links between nutrition and good health and is an expert on plant-based diets.

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