We’ve all heard the expression ‘you are what you eat’, but to what extent does making the right meal choices affect your mental wellbeing?

Here, we’ll look at some specifics on how food helps to fuel your mind, and how what we put on our plates can contribute to better brain health and improved cognition.

  • A balanced diet rich in healthy fats, antioxidants, vitamins, and minerals can provide the nutrients your brain needs.
  • Your gut microbiome plays a key role in brain function through the brain-gut axis.
  • Aim for a diet rich in complex carbohydrates, protein, omega-3 fatty acids, and fibre.
  • Avoid ultra-processed foods, sugary drinks and excessive alcohol.

How do nutrients affect your brain?

There are lots of factors involved when it comes to what and when you eat, and how it can affect how you feel. Eating well might not be a cure-all for every bout of the blues or day you’re feeling out of focus, but understanding how food affects your brain can be essential for keeping on top of your mental health.

So how do you eat to improve your brain health?

A diet rich in healthy fats, antioxidants, vitamins and minerals can provide you with nutrients that are all vital for your brain. Aim to eat foods that contain essential nutrients, such as omega-3 fatty acids, vitamin C and E, iron and magnesium. and avoid foods that are ultra-processed and provide little in the way of nutrition.

Additionally, deficiencies in zinc, B9 and B12 have been linked to irritability, low mood and fatigue,2 so eating a varied diet can help you cover all bases and give you the nutrients your brain and body need.

Blood sugar, also known as blood glucose, is your body’s main source of energy, and comes directly from the food you eat.1 If you don’t eat regularly, your blood sugar can fluctuate and make your moods do the same.

Choosing nutrient-rich foods that release sugar slowly can keep your brain and body energised throughout the day, and help you avoid crashing. Processed foods and baked goods that are rich in trans fats often contain added sugar, which can cause your blood sugar to spike excessively. They can also be low in fibre, which can contribute to these spikes. This yoyoing effect can impact how you feel as your energy levels bounce up and down. Studies have even found that poor blood sugar management can directly mirror mental health symptoms.3

Below, we’ll look closer at some biological processes that explain the link between physical and psychological health, as well as looking at specific foods that can benefit your brain.

Your gut microbiome

Microbes can be found all over your body, in areas like your skin, your nose, and most importantly when it comes to what you eat — your gut.4 Each person has their own microbiome. It’s a collection of microorganisms that work together to help carry out vital physiological functions to protect your immune system and keep you healthy.

The gut microbiome (or gut flora) is made up of all the microbes that inhabit the gastrointestinal tract (GI). It’s made up of trillions of friendly bacteria. The role of the GI is to help you digest food and absorb nutrients. While there’s no one-size-fits-all approach when it comes to how much of each nutrient you need, research has found that eating well generally means you’re more likely to be in better health.

Fibre is digested by your gut microbiome and turned into healthy nutrients. Fruit and vegetables are both high in fibre, so it’s no surprise people are constantly reminded to try and eat five portions of fruit and vegetables a day. An extension of this adage is the ‘30 plants per week’ challenge. This idea, which came from a gut microbiome research group called the American Gut Project,18 indicates that eating a bigger variety of plant foods is associated with better gut health.

In one study, health conditions like obesity, type 2 diabetes and heart disease were linked with eating processed food and unhealthy meats. A diet that involved high-fibre vegetables, nuts, and animal products such as eggs and fish had the opposite effect, and was shown to help the health of the gut microbiome.5

The ‘brain-gut axis’

Your gut and your brain are in constant communication with each other in a bidirectional way. This means rather than one influencing the other, there is a two-way communication channel where messages are sent back and forth. This process is known as the brain-gut axis, and happens via the vagus nerve, one of your body’s most important nerves.

In the way that your brain can influence intestinal activity, your gut can do the same for your mood. This is one reason why psychological disorders like depression and anxiety have been linked with physical conditions such as irritable bowel syndrome (IBS) and Crohn’s disease.5 Stress has been known to impact the balance of gut bacteria, so unmanaged stress that’s contributing to your physical health can in turn affect your mental health and moods.17

Over 95% of your body’s serotonin, a neurotransmitter that plays a vital part in regulating your sleep, appetite, and mood, is produced in the gut. Dopamine and gamma-aminobutyric acid (GABA) are also influenced by the gut microbiome. Like serotonin, they’re neurotransmitters involved in psychological processes that contribute to your mental health.

So does keeping your gut microbiome healthy mean your mood will follow?

From a holistic standpoint, looking after your gut flora is just one small part of a wider approach to your health. Research has shown that anxiety and depression have both responded well to an increase in gut microbiome diversity as a result of making healthier diet choices.6

Probiotics and prebiotics

Probiotics are any foods containing live microorganisms that are thought to have health benefits. Usually they’ll be advertised as containing ‘friendly’ or ‘good’ bacteria, and are commonly found in yoghurts and fermented food like kimchi. You can also get them as supplements. Probiotics can help restore your gut’s natural bacteria balance.14

Research is ongoing about the effects of probiotics on the brain-gut axis, but studies have found that they might improve cognitive function, as well as lowering anxiety and stress.11

Prebiotics, which sound similar, feed the good bacteria in your gut. These are usually high-fibre foods. Apples, oats, barley, and bananas are all prebiotics, but there are others, including leeks, asparagus, and onions. Adding foods to your diet that contain both probiotics and prebiotics can contribute to improved digestion and better gut health.

Which foods are good for your brain?

When looking for foods that will benefit your brain health, it’s better to think of the bigger picture instead of limiting your diet. The food you eat each day should be varied and include a good balance of protein, fat, carbohydrates and fibre.

Your brain needs energy, and lots of it. In fact, 20% of your metabolic energy is used by your brain, even when you’re resting.7 If you want energy that will bolster your brain power throughout the day, try to eat complex carbohydrates. The sugar molecules in complex carbs are longer than those found in their simpler ones, which means the energy they provide you will be more sustained.7 They’re also a great source of fibre, which supports gut health and aids digestion. Aim to eat a mix of whole grains, and starchy vegetables like potatoes and peas.

Protein is essential for muscle and tissue repair, and for producing important brain chemicals. Amino acids, which protein is made up of, are essential for brain health. One amino acid, tryptophan, which produces serotonin and melatonin, has been linked with impaired cognition when levels are low.8 Try to include proteins in your diet that have the additional benefit of omega-3 fatty acids, such as walnuts and fatty fish. Omega-3s have been linked to better blood flow to the brain, as well as improved learning and memory.9

Developing a healthy relationship with food can help you make the right choices when it comes to eating habits that will benefit your brain. As you make adjustments to your diet, it’s equally as important to make sure you hydrate properly. Brain mass is made up of around 75% water, so it’s no surprise that dehydration can affect cognitive performance.10

Which foods are bad for your brain?

The foods to avoid when it comes to improving your mental health are probably the ones you suspect aren’t giving you much in the way of nutrition. We’ve already mentioned the impact fluctuating blood glucose levels can have on your brain, so you may wish to avoid foods that have a high sugar content. The same goes for fizzy drinks – if you need a carbonated fix, try soda water as a healthy substitute. It’s also worth reading the ingredient labels on ‘diet’ soft drinks. The sugars are usually replaced with artificial sweeteners, and some, such as aspartame, have been linked to migraines, anxiety and insomnia.2

Reducing your alcohol intake is an easy win for both weight loss and brain health. Besides its detrimental effects on brain health, alcohol is often high in calories and can contain a surprising amount of sugar. If you overdo the amount you drink, the impact on your blood sugar can cause food cravings the day after. With a sore head and low energy, it’s easy to reach for the comfort of fast-food. It’s fine to indulge in both now and then, but it’s good to be mindful of the knock-on effect alcohol can have on your physical and mental health.

Eating on the go can sometimes mean making choices in a hurry, so where possible, steer clear of ultra-processed foods as they often contain trans fats and refined carbohydrates. Ready meals might be convenient, but they often contain artificial additives that can have negative effects on your brain.15 The saturated fat content in pre-packaged fast-food can be deceptively high, so try to limit your intake.

You don’t need to get on your own back about making impeccable choices whenever you’re in a rush, but your brain will thank you for being mindful about what goes in your basket.

What’s the best diet for mental health?

There isn’t a specific meal plan guaranteed to improve your mental health. However, if you’re trying to eat better and you’re looking for inspiration, there is a diet with proven health benefits that you might want to look into further.

First described by Ancel Keys in 1975, the Mediterranean diet combines a high amount of healthy oils, traditionally olive oil, with vegetables, fish and legumes (such as beans and peas).13 Whole grains and fruit are also part of the diet. The emphasis is placed on getting a higher amount of oil from vegetables as opposed to other sources, like meat and cheese, although some fermented cheese is encouraged for its effects on healthy gut bacteria. The Mediterranean diet is also high in fibre and antioxidants.

This approach to meal planning might be a good place to start if you want to eat in a balanced way. Being mindful of the essential nutrients needed for brain health means you’ll know what to put in your basket when it comes to buying food.

It’s worth remembering that clinical mood conditions, such as anxiety and depression, are unlikely to resolve by changing your diet alone.